{"id":1256,"date":"2019-09-02T06:34:32","date_gmt":"2019-09-02T06:34:32","guid":{"rendered":"https:\/\/greenmanpublishing.com\/?page_id=1256"},"modified":"2019-09-17T23:16:25","modified_gmt":"2019-09-17T23:16:25","slug":"watering-plants","status":"publish","type":"post","link":"https:\/\/greenmanpublishing.com\/index.php\/2019\/09\/02\/watering-plants\/","title":{"rendered":"Watering plants"},"content":{"rendered":"\n

Plants and water<\/strong><\/p>\n\n\n\n

You don\u2019t need to be a gardener to understand that water is the\nlife blood of the garden (or the world for that matter). With water you have a\nluxuriance of green growth all summer, without it you have a brown desert. In\ndry areas, making sure that your plants have all the water they need is one of\nyour primary summer tasks. In such \nplaces it determines how much you can grow.<\/p>\n\n\n\n

Why plants need water<\/strong><\/p>\n\n\n\n

Plants are mostly composed\nof water (80 – 95%) and it is an essential part of every aspect of the plants\nlife. It is needed for photosynthesis, growth, keeping cells (and the plant\nitself) rigid and the transport and absorption of nutrients. Less than 5% of\nthe water taken up by the roots is actually incorporated into the plant, which\nis why it takes 200 – 500 units of water to produce one unit of dry plant\nmaterial. The rest of the water is transpired out into the air. It\u2019s been\nestimated that an acre of corn may use 3-4000 gallons of water per day, which\nhelps to explain how 10% of the water in the atmosphere comes from plants. <\/p>\n\n\n\n

This \u201clost\u201d water actually\nhas an essential role in plant growth. It is a part of the transpiration\nprocess, whereby the plant moves water, nutrients, wastes and manufactured\nfoods around. It also helps to keep it cool and turgid (rigid). See Plant growth for more on this.<\/p>\n\n\n\n

Plants\nalso need the water that remains in the soil and makes up the soil solution.\nThis is the route by which nutrient ions are transported around the soil and\nhow they end up in plant roots. Water is also essential for the soil organisms\nthat feed plants and is a factor in both mechanical and chemical weathering of\nsoil, which liberates plant nutrients (see Soil <\/strong>for more on this).<\/p>\n\n\n\n

Effects of too little water<\/strong><\/p>\n\n\n\n

In many areas water is the\nmost common factor limiting plant growth (even in relatively humid climates).\nIf a plant can\u2019t get enough water it closes its stomata to prevent loss through\ntranspiration. This prevents the plant taking in carbon dioxide and without\nthis photosynthesis can\u2019t take place. When this happens the plant must live off\nof its stored food reserves, so actually consumes food, rather than producing\nit. Consequently growth slows down, or stops completely. Of course this then\naffects food storage, flowering and subsequent fruiting (flowers and fruits\noften drop).<\/p>\n\n\n\n

Water stress doesn\u2019t only\nslow growth and reduce yield. It may also cause plants to bolt, or affect the\nquality of the edible part, making them fibrous (their cells get thicker and\ntheir stems tougher), pungent or bitter. One of the reasons the French market\ngardeners grew such large quantities of high quality vegetables was that they\nensured their crops got all the water they needed at all times.<\/p>\n\n\n\n

Effects of too much water<\/strong><\/p>\n\n\n\n

Too much water can delay\nflowering and fruiting and causes plants to make succulent growth that is\nattractive to disease and insect pests. This succulent growth contains a lot of\nwater, so is less nutritious and less flavorful (the latter may not be a bad\nthing with strongly flavored crops). If the soil becomes waterlogged there\nisn\u2019t enough air in the soil and roots may die.<\/p>\n\n\n\n

The spacing of plants in the\nbed has an effect on irrigation practices. Obviously the more plants in a given\narea, the more water they will extract from the soil. If you fill a bed with\ntomato  plants 18\u02dd apart you may have to\nwater every few days, if you plant them 6 feet apart you may never have to\nwater them at all (there may already be enough water stored in the soil).<\/p>\n\n\n\n

Individual plant requirements<\/strong><\/p>\n\n\n\n

Crop plants vary greatly in\ntheir need for water. Celery originally grew in marshes and like lots of water,\nwhile Watermelon comes from a semi- desert and can make do with very little.\nDeep-rooted crops generally need irrigating less frequently than shallow rooted\ncrops. Some plants need water constantly, others have a critical stage of\ngrowth when extra water can greatly increase the final harvest (in some cases\nthis can double the final yield).<\/p>\n\n\n\n

The stage of growth affects\nhow often you need to water. Root growth is rapid in young vigorously growing\nplants (as much as an inch a day), but it slows considerably as a plant matures\nand starts to flower and set fruit.<\/p>\n\n\n\n

Young plants<\/strong>: These use\nless water than larger plants,but need it more frequently because their\nroots are small and their sparse foliage doesn\u2019t shade the soil very well (so\nevaporation is greater).<\/p>\n\n\n\n

Older plants<\/strong>: Use more\nwater, but have deeper roots. They also have larger leaves that form their own moist shady\nmicroclimate which reduces evaporation.<\/p>\n\n\n\n

Leaf crops<\/strong>: These\nneed a steady supply of moistureif they are to produce heavy yields of\ntasty succulent leaves. Water stress can have a dramatic effect on quality,\nplants may get fibrous, develop unpleasant flavors, or bolt prematurely. Keep\nthe soil constantly moist for these crops.<\/p>\n\n\n\n

Root crops<\/strong>: These have their greatest need for water when the roots are sizing up, but should always receive a steady supply.\nWater stress may cause them to bolt or develop unpleasant flavors. Irregular\nwatering, alternately too much and too little, can stimulate them to put on\nlittle spurts of growth, which can cause them to grow unevenly and split.<\/p>\n\n\n\n

Fruit and seed bearing crops<\/strong>: Fruit crops also respond to regular watering with heavy production of lush foliage,\nbut this isn\u2019t necessarily a good thing, as it often delays flowering.\nConversely the \u201cstress\u201d of infrequent watering can actually encourage\nflowering.<\/p>\n\n\n\n

When\nthe fruit is setting and sizing up, they need extra water, so make sure you\ngive them enough when the flowers and fruits appear (or they may drop off).\nThey are vulnerable to water stress at this time, not only because water is\nneeded to size up the fruit, but also because root growth slows down at this\nstage. Water stress at this time can reduce the final yield considerably\n(though it may make the fruit sweeter).<\/p>\n\n\n\n

Bulb crops<\/strong>: These need the most water when young, less when they\nare maturing and none at all when they are curing.<\/p>\n\n\n\n

Soil and water<\/strong><\/p>\n\n\n\n

Water enters the soil as\nrainfall and leaves via plant roots, evaporation or gravity (it drains away).\nWater isn\u2019t static in the soil, it can move downward by gravity and  upwards and sideways by capillary action (which\nis actually the attraction of molecules to each other). About 25% of the volume\nof the average soil is composed of water, but this fluctuates with the weather.<\/p>\n\n\n\n

Infiltration<\/strong><\/p>\n\n\n\n

The rate at which water\nenters the soil is known as its infiltration capacity and is largely dependent\non the soil structure and texture (especially of the surface layer). If the\ninfiltration capacity is low, water tends to puddle on the surface, rather than\nsoaking in. This may then run off downhill (potentially causing erosion) and\ndisappear. This wastes water that could have helped us to grow plants, so we\nmust do everything we can to ensure that the soil absorbs all the rainfall that\nlands upon it.<\/p>\n\n\n\n

How water enters the soil<\/strong><\/p>\n\n\n\n

When a drop of water enters\nthe soil it connects with the nearest soil particles and is incorporated into\nthe film of water that surrounds them. This water is held on to the particles\nby the force of adhesion, which allows the film to build up around the particle\n(to a thickness of around 0.06 mm, to get specific). When each particle has as\nmuch water as it can hold, the excess water fills up the spaces between the\nparticles (the micropores). All of this water is known as capillary water,\nbecause it can move around the soil by capillary action.<\/p>\n\n\n\n

Any water entering the soil\nafter the micropores are full, goes in to the spaces between the aggregates\n(the macropores). This water is known as gravitational water, for the obvious\nreason that it moves by the force of gravity and isn\u2019t physically held by the\nsoil at all.<\/p>\n\n\n\n

If more water enters the\nsoil it penetrates deeper, by force of gravity, connecting with all available\nsoil particles and filling up all available pore spaces, until it hits the\nwater table (where the soil is permanently saturated).<\/p>\n\n\n\n

If so much water enters the\nsoil that all available pore spaces are filled right down to the water table,\nthe soil is said to be at saturation point. Any more water falling on the soil\nafter this point can\u2019t soak into the saturated soil and so either stands on the\nsurface or runs off.<\/p>\n\n\n\n

When water stops entering\nthe soil, the gravitational water in the macropores slowly drains away and is\nreplaced by air. When all of this water has drained off (which may take days),\nthe soil particles and micropores are left holding as much capillary water as\nthey are physically able (the 0.06 mm thick film) and the soil is said to be at\nfield capacity. This is the ideal water level for most plants, with the water\nforming a continuous film from surface to water table, but with the larger\nmacropores still filled with air. The amount of water the soil can hold in this\nstate is known as its moisture holding capacity.<\/p>\n\n\n\n

How water moves in soil<\/strong><\/p>\n\n\n\n

The soil near the surface\ndries out most rapidly, as its moisture is removed by evaporation and by plant\nroots. This is replaced by capillary water, which moves through the soil pores\nfrom wetter areas. This happens because the film around a soil particle gets\nthinner as it dries out, causing its surface tension to increase, which pulls\nwater from wetter particles. In this way water may move in any direction, from\nwetter areas to drier ones, until all are equally moist. In practice they never\nbecome equally moist, because water continues to be lost (by evaporation, or to\nplant roots) as fast as it can be replaced.<\/p>\n\n\n\n

If water is continually\nremoved from the soil without replenishment, it is eventually depleted to the\npoint where more water can\u2019t move through the soil quickly enough to replace\nthat consumed. Capillary movement is related to tension and decreases as the\nsoil film dries out, until it essentially ceases as the soil gets close to\nwilting point. Once the continuous film of soil moisture is broken, the plant\ncan no longer get enough water to replace that transpired, so it shuts down its\nstomata, wilts and stops growing. If there is still moisture deep in the soil\nthis reduction in demand may enable more water to move up into the soil around\nthe root zone. If this doesn\u2019t happen the plant may eventually die from lack of\nwater.<\/p>\n\n\n\n

The capillary movement of\nwater is too slow and limited to provide plants with sufficient water for good\ngrowth, so in dry soil their roots must search out water continuously. This is\nactually the main incentive for roots to grow into new soil (they can only grow\ninto moist soil). This root growth, combined with capillary movement, enables\nplants to get most of the available water in the soil.<\/p>\n\n\n\n

Available water<\/strong><\/p>\n\n\n\n

All of the water in the soil\nisn\u2019t of equal value for growing crops. As plants suck up water, the film of\nmoisture around each soil particle gets thinner and it takes more energy to get\nit. By the time the wilting point is reached, this film is so thin that plants\ncan\u2019t extract any more water from it.<\/p>\n\n\n\n

The remaining water is held\ntightly to the soil particles by electrical forces (at 15 times atmospheric\npressure) and is known as \u201chygroscopic water\u201d. Even though this water can\u2019t be\nused by plants, it is still important because water loving soil organisms live\nin it and can survive there even when the soil is very dry By determining the\namount of soil suction with a tensiometer, we can determine how much water is\navailable for plants. <\/p>\n\n\n\n

The soil water that plants\ncan use is called \u201cavailable water\u201d, or the soil reservoir. That which can\u2019t be\nused is called (appropriately enough) \u201cunavailable water\u201d and includes\ngravitational water and hygroscopic water.<\/p>\n\n\n\n

It is not good to let the\nsoil lose more than half of its available water, as the plants then have to\nwork harder to meet their needs. When a plant has to expend energy just to\nobtain water, it has less left over for growth, which then slows down. It is\nyour job as a gardener to give your crops all the water they need, so they can\ngrow as efficiently as possible.<\/p>\n\n\n\n

Factors affecting the loss of water from the soil<\/strong><\/p>\n\n\n\n

Evaporation<\/strong>: On a hot\nday a bare soil can lose a lot of water through evaporation. Cultivation increases this loss by\nincreasing the surface area of the soil and so exposing more soil moisture to\nthe air. Sandy soils tend to lose less water from evaporation than clay soils,\nbecause they tend to dry out on the surface creating a dust mulch effect (and\nthere is less capillary action to bring more moisture to the surface).<\/p>\n\n\n\n

Wind increases evaporation\nand is another reason why the garden should be sheltered from strong winds.<\/p>\n\n\n\n

A layer of mulch stops water\nloss by evaporation almost completely. Not only does it prevent sunlight\nhitting the soil, it also creates a humid layer under the mulch.<\/p>\n\n\n\n

Transpiration<\/strong>:\nThe amount of water a plant losesthrough transpiration is determined by\ntemperature, humidity and sun intensity. On a hot sunny summer day a plant may\nuse eight times as much water as it does on a cool cloudy spring day. Strong\nwind can increase transpiration losses even further.<\/p>\n\n\n\n

Soil texture and water<\/strong><\/p>\n\n\n\n

The ability of the soil to\nhandle water is largely determined by its texture, structure and organic matter\ncontent.<\/p>\n\n\n\n

Sand<\/strong>: These\nsoils may hold about 10% water at field capacity. The large pore spaces enable water to enter and leave\neasily, so it fills up or dries out fairly quickly. Such soils don\u2019t have a\nlarge reservoir of water, so must be watered frequently to keep crops supplied\nin dry weather. Offsetting this to some extent is the fact that roots can\npenetrate more easily and deeply into sandy soils in search of water. Some\nsandy soils are hard to re-wet if they dry out, water simply rolls off them.<\/p>\n\n\n\n

Clay<\/strong>: These\nsoils can hold as much as 40% water atfield capacity, but a much\ngreater proportion of this is unavailable when compared to a sandy soil. When a\nclay soil dries out it shrinks and cracks and these cracks can damage roots and\nmake it hard to re-wet the soil (water drains down the cracks before it can\nsoak into the soil). The infiltration rate in a poor clay soil is low, because\nwater enters the small pores so slowly, it often puddles on the surface and\nruns off. Water also drains slowly, which can be a problem in wet climates.\nClay soils have a large soil reservoir, so don\u2019t need watering as frequently as\nsandy ones.<\/p>\n\n\n\n

Silt<\/strong>: These\nsoils have characteristics somewherebetween those of sand and clay.<\/p>\n\n\n\n

Soil structure<\/strong><\/p>\n\n\n\n

A well-structured soil has a large volume of pore space, with lots\nof macropores that allow water to percolate freely and micropores that hold\nwater.<\/p>\n\n\n\n

Soil organic matter<\/strong><\/p>\n\n\n\n

Organic matter actually acts\nlike a sponge, absorbing and holding excess water and only releasing it when\nthe film of moisture around the soil particles is depleted. This greatly\nincreases the water holding capacity of light sandy soils.<\/p>\n\n\n\n

Organic matter also improves\nthe crumb structure of a soil, which increases the amount of pore space. This\nincreases aeration and improves drainage, making it easier for roots to\npenetrate deeply in search of water. This is particularly valuable for heavy\nclay soil.<\/p>\n\n\n\n

Slope<\/strong><\/p>\n\n\n\n

A slope drains better than\nflat land and so dries out faster (especially in light soils). South and west\nfacing slopes dry out most rapidly because of their increased solar gain. Land\nat the bottom of a slope gets extra water as it drains down from above.<\/p>\n\n\n\n

Climate<\/strong><\/p>\n\n\n\n

Climate\naffects how much water plants use and determines whether you can get away with\noccasional hand watering, or whether you must irrigate your plants from\nseedling to harvest. In hot arid areas you would expect to have to irrigate\nplants regularly, but even where summer rainfall is regular, loss by\nevaporation and transpiration often exceeds rainfall. In such cases some\nirrigation will be necessary to achieve maximum yields. This is especially true\nin intensive beds, as the fast growing, closely spaced, plants need a lot of\nwater.<\/p>\n\n\n\n

Climate and soil water<\/strong><\/p>\n\n\n\n

There is a considerable\nseasonal variation in the amount of water in the soil.<\/p>\n\n\n\n

The most obvious reason for\nsuch fluctuation is rainfall. In many areas this is seasonal, some seasons\nbeing much wetter than others. Where I live on the West coast, rain is abundant\nin winter, but pretty much non-existent in summer.<\/p>\n\n\n\n

Another reason is temperature.\nIn the cool weather of spring and autumn there may be very little evaporation\nfrom the soil and less transpiration from plants. This means that the soil\ndries out much more slowly than in summer. Often there is no need to water at\nall at these times, especially in spring when the soil is full of water from\nwinter rains.<\/p>\n\n\n\n

Always consider the weather\nbefore watering, never water routinely. If possible don\u2019t waste water by\nirrigating before rain (somehow a particularly conscientious watering always seems\nto bring rain.) A rain gauge can help you to determine the quantity of both\nnatural rainfall and overhead irrigation.<\/p>\n\n\n\n

Water holding capacity of\nsoils<\/strong><\/p>\n\n\n\n

The amount of water a soil\ncan hold is determined by its texture and organic matter content. Soil depth is\nalso significant, in that a deep soil has a much greater storage volume than a\nshallow one.<\/p>\n\n\n\n
\n Water in the top 12\u02dd of soil<\/strong>\n  \n <\/td><\/tr>
\n Soil<\/strong>\n  \n <\/td>\n Field <\/strong>\n capacity<\/strong>\n <\/td>\n Permanent\n <\/strong>wilting\n point<\/strong>\n  \n <\/td>\n Available water<\/strong>\n  \n <\/td><\/tr>
\n Sand<\/strong>\n  \n <\/td>\n 1 \u00be\u02dd<\/strong>\n  \n <\/td>\n \u215b\u02dd<\/strong>\n  \n <\/td>\n 1 \u215d\u02dd<\/strong>\n  \n <\/td><\/tr>
\n Loam<\/strong>\n  \n <\/td>\n 2 \u00bc\u02dd<\/strong>\n  \n <\/td>\n \u00bc\u02dd<\/strong>\n  \n <\/td>\n 2\u02dd<\/strong>\n  \n <\/td><\/tr>
\n Silt loam<\/strong>\n  \n <\/td>\n 2 \u00bd\u02dd<\/strong>\n  \n <\/td>\n \u00bc\u02dd<\/strong>\n  \n <\/td>\n 2 \u00bc<\/strong>\n  \n <\/td><\/tr>
\n Clay<\/strong>\n  \n <\/td>\n 2 \u00bd\u02dd<\/strong>\n  \n <\/td>\n \u00bd\u02dd<\/strong>\n  \n <\/td>\n 2\u02dd<\/strong>\n  \n <\/td><\/tr>
\n Peat<\/strong>\n  \n <\/td>\n 4 \u00be\u02dd<\/strong>\n  \n <\/td>\n 1 \u00bc\u02dd<\/strong>\n  \n <\/td>\n 3 \u00bd\u02dd<\/strong>\n  \n <\/td><\/tr><\/tbody><\/table>\n\n\n\n

Water sources and quality<\/strong><\/p>\n\n\n\n

It\u2019s worth thinking about\nthe purity of your water source. In arid areas dissolved salts can build up in\nthe soil and become quite toxic. Hard water contains calcium and magnesium and\nmay raise the pH. In some areas surface water is quite acid (from acid rain)\nand will lower the soil pH. If you have any suspicions you can have your water\ntested (it may be worth having an agricultural water test done when having your\nsoil tested).<\/p>\n\n\n\n

The best water for plants is\nrainwater, as it contains small quantities of nitrogen, sulfur and other\nnutrients. On average half of all rainfall falling on the ground runs off and\nis lost. You should do everything you can to ensure that the soil retains as\nmuch rainfall as possible.<\/p>\n\n\n\n

If you have rain barrels\nunderneath all of your downspouts, you can collect a surprising amount of water\nfrom your roof. See below for more on Rainwater collection<\/strong>.<\/p>\n\n\n\n

Probably\nthe commonest source of water for gardeners is the utility company. City water\ndoesn\u2019t contain many nutrients and often contains a lot of chlorine (and\nsometimes fluoride) which plants and soil organisms don\u2019t like (I once tried to\nsprout Alfalfa seed in heavily chlorinated water and it kept rotting). If you\nare watering seedlings you could leave chlorinated water in open barrels for a\nday or so, to allow the chlorine to dissipate. Don\u2019t use water that has been\nthrough a chemical water softener, as it contains a lot of salt.<\/p>\n\n\n\n

City water is becoming\nexpensive in many areas and increasingly unreliable due to droughts and hose\npipe bans. One advantage is that it has good pressure for overhead irrigation.<\/p>\n\n\n\n

Many suburban and rural\ngardeners get their water from wells. This is often superior to city water, but\nsometimes contains large amounts of dissolved salts. An increasing number of\nwells are contaminated from various industrial and farm sources, or from lawn\nchemicals.<\/p>\n\n\n\n

In some situations you may\nbe able to get water from clean rivers, lakes, or streams. This is usually of\ngood quality, though you should be sure of your legal position before using it.\n<\/p>\n\n\n\n

Gray water<\/strong><\/p>\n\n\n\n

Gray water is any water that\nhas been used in the house, but doesn\u2019t contain sewage (which is known as black\nwater). Actually it may contain very dilute sewage, as well as bacteria,\nviruses and a variety of chemicals so it isn\u2019t completely harmless. The average\nhouse uses 100 – 200 gallons of water a day, which could be all of the water\nyou need for your garden. This water is already piped, and just requires a\nlittle modification of your plumbing (and some of your more wasteful habits)\nLogic says that if you can re-use some of this water you should, though it may\nbe illegal to do so in many places, due to health code restrictions.<\/p>\n\n\n\n

In wet climates using\nuntreated gray water isn\u2019t really worthwhile (except in times of drought). In\ndry climates it doesn\u2019t make sense not to use it. In an ideal world you would\nuse the gray water for flushing toilets and would use the fresh water thus\nsaved for irrigation. This isn\u2019t always practical though<\/p>\n\n\n\n

Gray water should be used\ncarefully as it does contain some things plants don\u2019t like. Use on perennials\nand shrubs rather than annuals, keep it off foliage and rotate its use around\nthe garden (don\u2019t put it all in one place). Use fresh water in between the gray\nwater irrigations.<\/p>\n\n\n\n

The cleanest gray water is\nthat wasted while waiting for the hot water tap to get hot. The next cleanest\ncomes from the shower and bathtub, then the washing machine and finally from\nthe dishwasher and kitchen sink (the dirtiest). The latter is rich in plant\nnutrients, but also contains grease and oils and lots of food particles, so\npotentially causes a lot more problems. If you are adverse to disgusting things\nyou should forget about using kitchen sink water. Instead try washing your\nvegetables outdoors in the garden sink. This water can go directly onto the\ngarden and is very clean.<\/p>\n\n\n\n

If you intend to use gray\nwater for irrigation you should alter your washing habits to reduce its\ntoxicity. Be careful which soaps, shampoos and detergents you use, no boron,\nhigh sodium, bleach (especially), water softeners, perfumes or lanolin.<\/p>\n\n\n\n

It is important that gray\nwater is used immediately and isn\u2019t stored for any length of time. Bacteria\nwill start to grow after a few hours and it will soon start to stink.<\/p>\n\n\n\n

A good way to use gray water\nis to irrigate compost crops, such as reeds or comfrey, grown in their own\nspecial bed. It can also be used for willows or bamboo. If you get really\nambitious you could create your own grey water treatment marsh to purify the\ngray water before use.<\/p>\n\n\n\n

Rainwater<\/strong><\/strong><\/p>\n\n\n\n

Where I live we get 3 – 8\nfeet of rain in winter and none at all in summer. In an ideal world we could\nstore some of that winter rain for use in summer.<\/p>\n\n\n\n

Infiltration<\/strong>: In-soil\nstorage is the cheapest and <\/strong>simplest way to store\nsignificant amounts of water. Your first priority should be to ensure that any\nrain that falls on your soil soaks in, rather than running off into drains. The\nsimplest way to do this is by ensuring that the ground is covered with\nvegetation, so water slowly soaks into the ground. On steeper slopes you may\nhave to create ditches, or swales, to intercept fast flowing runoff and hold it\nup long enough so that it can soak in. You could also terrace the land so water\ndoesn\u2019t run away.<\/p>\n\n\n\n

Of course water that is\nstored in the soil isn\u2019t as convenient or versatile as water stored in a tank\nor pond (from which it can be directed to where you need it).<\/p>\n\n\n\n

Probably\nthe cheapest way to store water is in a pond, Runoff from roads, paths and\nroofs could be channeled into ponds (lined with a rubber pond liner), for later\nuse for irrigation.<\/p>\n\n\n\n

Most houses already come\nwith a ready made rainwater collection system, the roof. If you have gutters\n(and you should) all you have to do is direct the water from the downspouts to\nsome kind of storage container. The water can even go uphill somewhat, so long\nas the tank is lower than the gutters themselves.<\/p>\n\n\n\n

To\nestimate how much rain you are likely to collect from your roof, you must first\ndetermine the square footage of the footprint of your roof (looking down\ndirectly from above, not its actual surface area). This is usually a little\nmore than the square footage of the upper floor of your house. Multiply this\nnumber by the average yearly rainfall in inches. Divide this number by 12 – get\nthe number of cubic feet of water. Then multiply this by 7.5 – get the number\nof gallons.<\/p>\n\n\n\n

For example, my roof is\napproximately 800 square feet and we normally get about 60 inches of rain per\nyear. This works out to 4800, which divided by 12 equals 4000. Multiply this by\n7.5 and you get 30,000 gallons of water. If only storing it were as easy as\ncalculating it!<\/p>\n\n\n\n

Rainwater storage<\/strong><\/p>\n\n\n\n

In areas with year round\nrainfall, storage doesn\u2019t present much of a problem. All you need to do is\nstore enough water from recent rains to see you through the rainless stretches.\nA couple of 50 gallon barrels might be enough, or you might use an above-ground\npool if you have lots of plants, or long dry spells.<\/p>\n\n\n\n

In areas with no rain for\nlong periods you need large capacity storage. The cheapest would be an\nabove-ground pool or a hole in the ground lined with plastic (or pond liner). A\nmuch more expensive (but durable) option would be a plastic water tank (or\nseveral).<\/p>\n\n\n\n

Watering technique<\/strong><\/strong><\/p>\n\n\n\n

Observation of soil and plants<\/strong><\/p>\n\n\n\n

The essence of good watering\nis making sure the plants get all the water they need, exactly when they need\nit and no more. If you irrigate a plant that already has an adequate supply, it\nwon\u2019t have any beneficial effect and you won\u2019t be using your water supply or\ntime efficiently. Conversely if you don\u2019t water until plants wilt, their growth\nwill be slowed (or they may even bolt), so again you won\u2019t be using your water\nsupply efficiently.<\/p>\n\n\n\n

The ideal time to water is\njust as the easily available water starts to run low, but before the plant has\nto start working harder to meet its needs (plants start to wilt much more\nreadily at this time). Generally when half of the available water is gone from\nthe soil you should irrigate. You have to watch the soil and plants carefully\nto know exactly when this stage is reached.<\/p>\n\n\n\n

Signs of <\/strong>water stress<\/strong><\/p>\n\n\n\n

You will soon learn how to\ntell when plants are stressed merely by their appearance. Serious water stress\nis pretty obvious because the plants wilt, but plants begin to show subtle\nsigns of stress long before lack of water forces them to shut down completely.\nAs water gets harder to obtain, plants begin to lose the sheen on their leaves.\nAs their stress increases they may sag slightly instead of standing rigidly\nupright and their leaf edges may start to curl. In extreme cases the growing\ntips and leaves go completely limp and if this continues for long they die and\ngo dry and crisp.<\/p>\n\n\n\n

Wilting isn\u2019t always a sign\nthat the soil is dry, in extremely hot and sunny weather plants sometimes wilt\nintentionally to reduce water loss. However they recover as soon as the\ntemperature drops. Some plants are much more prone to wilting than others,\nespecially those with thin, or big leaves, such as Rhubarb and the Cucurbits. Check\nyour plants for water stress in the cool of early morning or evening. If they\nare wilting at this time, they are seriously stressed and aren\u2019t getting enough\nwater (either the soil is dry, they are diseased, or they have root damage).<\/p>\n\n\n\n

Checking soil moisture<\/strong><\/p>\n\n\n\n

C<\/strong>heck the moisture level of the soil by digging down to the depth\nof your index finger (about 4\u02dd) and picking up a small amount of soil. If the\nsoil is so dry it won\u2019t squeeze into a ball, it probably needs water (remember\nthat clay forms a ball more easily than sand). Don\u2019t forget to fill up the hole\nagain afterward.<\/p>\n\n\n\n
\n Canary plants<\/strong>\n A canary plant is a plant\n that is particularly sensitive to lack of moisture and can warn you when the\n soil in your garden is getting dry (if you use your imagination this is\n somewhat like the canary in the coal mine warning of poisonous gases – hence\n the name). The sunflower is ideal for this, as it is one of the first plants\n to show signs of water stress. If you plant some sunflowers around your\n garden, you will have a handy indicator of when your soil is getting low on\n moisture. Whenever your sunflowers start to wilt, it is time to think about\n watering.\n  \n <\/td><\/tr><\/tbody><\/table>\n\n\n\n

Time of day to water<\/strong><\/p>\n\n\n\n

There is some controversy as\nto the best time of day to irrigate a garden. Some gardeners believe early\nmorning is best, because the water has a chance to soak into the soil before\nthe sun gets warm and is immediately available to the plants when they need it\nmost (which might have some relevance in sandy soils). They say evening\nwatering encourages pests and disease by leaving the soil moist all night. If\nyou have serious disease problems you may be best sticking to morning watering.\nMorning watering is also best in cool climates, as the soil can warm up quickly\nin the morning sun.<\/p>\n\n\n\n

Other gardeners prefer to\nwater in the early evening, after the hottest part of the day, but early enough\nto allow the plants and soil surface to dry out before dark. At this time the\nsoil is warm, so the water warms up quicker. Also the water has all night to\nsoak into the soil, so there is less loss from evaporation than with morning\nwatering. For this reason evening watering particularly lends itself to arid\nareas. Advocates of evening watering remind us that plants don\u2019t shut down\ncompletely at night, they still use water.<\/p>\n\n\n\n

Most gardeners avoid\nwatering in the middle of the day in hot weather, because any water on leaves,\nor the soil surface, will evaporate before it can do any good. This is\nparticularly true when using overhead watering. It is often said that in strong\nsunlight water droplets can burn the leaves by magnifying the suns rays, but I\nhave never seen this actually happen.<\/p>\n\n\n\n

Unless there is some\noverriding reason for using only evening or morning watering most people water\nwhen it is convenient, rather than to some schedule. Drip irrigation can be\nused at any time of day or night, but I would always avoid the hottest part of\nthe day.<\/p>\n\n\n\n

Increasing infiltration<\/strong><\/p>\n\n\n\n

Any soil crust should be\nbroken up before watering, as it can impede infiltration (see Soil Capping<\/strong> below). If your soil\ndoesn\u2019t absorb water easily, you can increase absorption by putting shallow\nholes in the bed with a fork, or dibbing larger holes between plants with a\ndibber (these tricks are particularly useful when hand watering). In some cases\nshallow furrows made along the contour with a rake will also work. You could\nalso put a lip around the edge of the bed to increase absorption (or simply\nhave a flat bed).<\/p>\n\n\n\n

How much water is enough?<\/strong><\/p>\n\n\n\n

How much water to apply\ndepends on many factors, climate, plants, soil type, plant spacing. One rule of\nthumb says you should give your plants 1\u02dd of water per week in summer and about\n\u00bd\u02dd in spring and fall (but of course it all really depends on temperature and\nhumidity). This works out to roughly \u2154<\/strong> gallon per square foot, 66\ngallons per 100 square feet, or 28,000 gallons per acre and should penetrate 6\n– 12\u02dd into the ground. By observing the soil and plants you will soon know if\nit is too much or too little.<\/p>\n\n\n\n

Intensively planted beds use\na lot of water because they are producing a lot of biomass in a short time;\nthere is a lot of growth going on. Fortunately these beds can store a lot of\nwater because of their high organic matter content.<\/p>\n\n\n\n

In rainy climates a rain\ngauge (or other container) is useful to monitor how much rain has fallen, so you\ncan decide when your crops need additional irrigation.<\/p>\n\n\n\n

Soil\nhas only a limited storage capacity, so you should only apply as much water as\nis needed to get it back up to field capacity. If the soil is very dry this can\nbe quite a lot. I have watered a clay soil for eight hours and only got about\nfour or five inches of penetration. If you add more than this, not only will it\nbe wasted, but the excess may actually damage the soil.<\/p>\n\n\n\n

Over-watering<\/strong>:\nThis encourages shallow rooting, <\/strong>making\nplants more vulnerable to drought and nutrient deficiencies. It may also leach\naway soluble nutrients and damage soil structure (especially on poor soils).<\/p>\n\n\n\n

Of course over-watering\nwastes water and in dry areas you simply can\u2019t afford this. Even in humid areas\nwater shortages are getting more frequent and water is getting more expensive.\nOver-watering also involves unnecessary work, as it takes time and effort to\nput water into the soil.<\/p>\n\n\n\n

Irregular watering<\/strong>: Too much water following <\/strong>too little water may cause fruit such as tomatoes to split. It can\nalso caused splitting in iceberg lettuce, cabbage  and Chinese cabbage .<\/p>\n\n\n\n
\n Deep watering or <\/strong>\n shallow watering<\/strong>\n  \n There\n are two schools of thought on watering, the deep infrequent waterers and the\n frequent shallow waterers. Initially your soil may determine which technique\n you use, but as the soil improves you can choose which one you prefer\n (climate and crop may also affect your choice.)\n  \n Deep watering<\/strong>\n When deep watering you\n fill the soil with as much water as it can hold (no more or you will waste\n water) and don\u2019t water again until the top few inches of soil have dried out.\n This forces your crops to send down deep roots to search for water and such\n plants are less susceptible to drought.\n  \n Deep watering has the\n advantage that it is less time consuming than shallow watering, but you have\n to careful to not let the soil dry out too much, It works best on deep, moisture retentive soils, . \n  \n Shallow watering<\/strong>\n Shallow watering means you\n water every day, so the soil is always at field capacity. This is probably\n the best strategy for watering light soils that can\u2019t hold a lot of water, though it will work on\n any soil. You might think this method contradicts the advice I gave above\n about watering deeply, but it really doesn\u2019t because you never allow the soil\n to dry out. This method may be better for the beginner, as there is more\n margin for error – if you forget to water for a day or two there is no harm\n done. \n  \n If you are going to be\n hand watering, then you are probably going to be shallow watering simply\n because of the time it takes to water deeply. \n \n  \n Shallow watering may be\n particularly appealing to obsessive compulsive people who like doing stuff,\n as it gives them something to do every day. \n  \n A\n variation on shallow watering in hot dry climates is to allow the subsoil to\n dry out. So long as you water regularly and don\u2019t allow the topsoil to dry\n out your plants will do okay.\n <\/td><\/tr><\/tbody><\/table>\n\n\n\n

How to apply water<\/strong><\/p>\n\n\n\n

Water should be applied to\nthe soil only as fast as it can soak in. This means it should fall on the bed\ngently, approximating a light rain shower, but not so fine that water is lost\nin clouds of mist. If you apply water faster than it can be absorbed it will\npuddle and the surface structure may break down. When this dries out a crust\nwill form, which further impedes water (and air) infiltration (this is known as\ncapping). Of course if water runs off of the beds it will be wasted (it may\nalso take soil with it).<\/p>\n\n\n\n

When the soil surface\nreaches saturation point it starts to glisten and as soon as this happens (or\njust before) you should move the water source momentarily to allow it to soak\nin. Overhead irrigation does this automatically of course.<\/p>\n\n\n\n

One of the commonest\nmistakes of novices (particularly when hand watering) is to water until the\nsoil surface looks nice and dark and wet and then move on. Appearances are\ndeceptive though, the surface may be thoroughly moist, but only an inch or so\ndown it may still be bone dry. If the soil is regularly watered in this way,\nplant roots will stay near the surface where the water is and the plants will\nbe very vulnerable to fluctuations in moisture content. If you are unable to\nwater such shallow rooted plants for a few days they will suffer.<\/p>\n\n\n\n

When\nwatering you must pay particular attention to the edges and ends, of the beds,\nas they dry out faster than the middle. Also watch any slopes facing away from\nthe water source, it will get less water than slopes facing towards the water\nsource.<\/p>\n\n\n\n

Some crops like to have\nwater applied to their leaves, but you should do it when they will dry out\nquickly (morning or early evening). Others (especially fuzzy ones) are very\nprone to disease if their leaves get wet, so you must avoid this if possible.<\/p>\n\n\n\n

If you are using sprinklers\nor oscillators you might want to put out a jar or rain gauge, to determine\nexactly how much water they are putting out.<\/p>\n\n\n\n

Always be careful of hoses\nwhen watering. It\u2019s easy to inadvertently drag the hose over the corner of the\nbed and wipe out plants.<\/p>\n\n\n\n

Absorption problems<\/strong><\/p>\n\n\n\n

If the top of a bed isn\u2019t\ntotally level, a lot of the water landing on it may run off before it has a\nchance to soak into the soil. Avoid this by making make sure the surface is\nlevel, or even slightly concave.<\/p>\n\n\n\n

In my garden I have an area\nof soil that is pretty much hydrophobic (water repellent) and it gives me the\nsame problem. Water simply pools up and runs off rather than soaking in. Adding\norganic matter can help to cure this in the long term. In the short term you\ncan poke a multitude of holes into the surface with a fork. <\/p>\n\n\n\n

After watering<\/strong><\/p>\n\n\n\n

Whether you water shallowly\nor deeply the soil should be very close to field capacity when you finish.\nExamine the soil carefully after irrigation (dig down again) to make sure it is\nthoroughly moist with no dry areas. Take note of how the soil and plants look\nafter watering and compare the bed to one which still needs irrigating.<\/p>\n\n\n\n

Soil capping<\/strong><\/p>\n\n\n\n

If water is applied in large\ndroplets, or faster than it can be absorbed into the soil, the surface\naggregates break down and the smaller particles wash down between the larger\nones. When the surface dries out this forms a dense crust known as a cap. This\nmost often happens on poorly structured soils, especially silt or fine sands,\nbut heavy watering can cause it to happen even on fairly good ones. This crust\nnot only reduces water penetration, but also hinders seedling emergence and may\ninhibit the exchange of air in the soil (which can cause toxic gases to build up\nand inhibit root growth).<\/p>\n\n\n\n

Small areas of crust can be\nbroken up with the fingers. Use a hoe for larger areas. A thin layer of mulch\nwill help to prevent most surface crusting.<\/p>\n\n\n\n

Disease and watering<\/strong><\/p>\n\n\n\n

In some climates careless\nwatering can lead to fungus disease problems in vulnerable crops. If you must\nuse overhead watering do it in the morning or early evening so the leaves and\nsoil surface can dry out quickly. Handling wet foliage can also spread some\ndiseases, so don\u2019t work near newly watered plants until their leaves have dried\noff. Wet foliage is also heavy, so wet plants may be easily damaged or knocked\nover.<\/p>\n\n\n\n

Algae<\/strong><\/p>\n\n\n\n

If your soil gets covered in\na coat of green algae it is usually because it is staying wet all of the time.\nThis means you are watering too much for the prevailing conditions. While not\nreally serious, this can be detrimental in that it tends to seal the surface of\nthe soil, preventing good exchange of air (as with Soil capping<\/strong>).<\/p>\n\n\n\n

If this happens allow the\nsoil surface to dry out and cultivate lightly to get air into the soil. In\nfuture allow the soil surface to dry out between irrigations.<\/p>\n","protected":false},"excerpt":{"rendered":"

Plants and water You don\u2019t need to be a gardener to understand that water is the life blood of the garden (or the world for that matter). With water you … Read More<\/a><\/p>\n","protected":false},"author":2,"featured_media":1750,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[5],"tags":[],"class_list":["post-1256","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-gardening-techniques","entry"],"jetpack_featured_media_url":"https:\/\/greenmanpublishing.com\/wp-content\/uploads\/2019\/09\/watering.jpg","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/greenmanpublishing.com\/index.php\/wp-json\/wp\/v2\/posts\/1256","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/greenmanpublishing.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/greenmanpublishing.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/greenmanpublishing.com\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/greenmanpublishing.com\/index.php\/wp-json\/wp\/v2\/comments?post=1256"}],"version-history":[{"count":1,"href":"https:\/\/greenmanpublishing.com\/index.php\/wp-json\/wp\/v2\/posts\/1256\/revisions"}],"predecessor-version":[{"id":1751,"href":"https:\/\/greenmanpublishing.com\/index.php\/wp-json\/wp\/v2\/posts\/1256\/revisions\/1751"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/greenmanpublishing.com\/index.php\/wp-json\/wp\/v2\/media\/1750"}],"wp:attachment":[{"href":"https:\/\/greenmanpublishing.com\/index.php\/wp-json\/wp\/v2\/media?parent=1256"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/greenmanpublishing.com\/index.php\/wp-json\/wp\/v2\/categories?post=1256"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/greenmanpublishing.com\/index.php\/wp-json\/wp\/v2\/tags?post=1256"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}