\u2022 Well drained and well\naerated. <\/strong><\/p>\n\n\n\n \u2022 Hold a lot of water. <\/strong><\/p>\n\n\n\n \u2022 Have a fairly neutral\npH. <\/strong><\/p>\n\n\n\n \u2022 Don\u2019t crust easily. <\/strong><\/p>\n\n\n\n \u2022 Are firm enough to\nprovide a strong anchorage for roots. <\/strong><\/p>\n\n\n\n \u2022 Have enough structural\nstability to resist compaction, even though it has a lot of pore space. <\/p>\n\n\n\n Buy or make?<\/strong><\/p>\n\n\n\n There are lots of\ncommercially available seed starting mixes and if you are only going to start\nsmall quantities of seedlings (or don\u2019t have much room to store materials) you\nmight want to simply buy a bag. Just make sure it is formulated for seed\nstarting and ideally is 100% organic. It is much cheaper to make your own\nhowever and this is the way to go if you wish to grow a lot of plants.<\/p>\n\n\n\n Making your own sowing mixes<\/strong><\/p>\n\n\n\n Sowing mixes are composed of\nseveral different ingredients, each of which fulfils a specific function in the\nmix:<\/p>\n\n\n\n \u2022 Most mixes contain a\nlarge proportion of organic matter (compost, peat moss, leaf mold) to provide\ngood water retention and aeration. <\/p>\n\n\n\n \u2022 The mix should contain\na coarse material (sand, vermiculite, perlite) to provide good drainage, as\norganic material alone tends to waterlog easily. <\/p>\n\n\n\n \u2022 The mix must also\ncontain a source of nutrients (compost, garden soil, or a fertilizer mix). It\ndoesn\u2019t need to have a very high nutrient content, because we want the\nseedlings to send out vigorous roots to search for nutrients. If the mix is too\nrich the plants get lazy and don\u2019t do this. Pricking out and potting mixes must\ncontain more nutrients, as the plants are bigger and have greater needs. <\/p>\n\n\n\n \u2022 The pH of the\ningredients should be a fairly neutral 6.0 – 7.0, similar to that of a good\ngarden soil. <\/p>\n\n\n\n \u2022 The mix should be free\nof weed seeds. It\u2019s much better if it doesn\u2019t grow more weed seedlings than\ncrop seedlings. <\/p>\n\n\n\n \u2022 The ingredients should\nbe free of disease and insect pests. <\/p>\n\n\n\n \u2022 The mix should also be\nlow in salts which could burn delicate seedling roots. <\/p>\n\n\n\n Sowing mix recipes<\/strong><\/p>\n\n\n\n Making mixes is a little like cooking, some people prefer to stick rigidly to the recipe, other people prefer to improvise with what\u2019s available. I’m giving these to give you an idea of what is involved, but I rarely stick to any one formula. <\/p>\n\n\n\n Screening<\/strong><\/p>\n\n\n\n All of the ingredients for\nsowing mixes are screened to take out sticks, stones and other debris, and to\nreduce them to a uniform texture. The ingredients for soil block or plug tray\nmixes should be sifted through a \u00bc\u02dd mesh. Those for flat, cell pack, pricking\nout and potting mixes can be coarser, so sift them through a \u00bd\u02dd mesh.<\/p>\n\n\n\n Mixing<\/strong><\/p>\n\n\n\n Small quantities of mix are\nusually made up in a wheelbarrow or large plastic tub. Larger quantities are\nmost easily mixed on a concrete floor. Just spread the materials out, one on\ntop of the other, in a big pile.<\/p>\n\n\n\n Then turn the pile three\ntimes to thoroughly mix all the ingredients together. Do this by simply moving\nthe pile a couple of feet, move it back again and then move it a third time to\nwhere you will actually store it. If you have two wheelbarrows, you can mix it\nby simply moving it from one to the other until it is thoroughly mixed<\/p>\n\n\n\n Moisture level<\/strong><\/p>\n\n\n\n Make\nsure the materials for the mix are at their proper moisture level (not too wet\nor dry). The moisture level of flat and plug tray mixes can be tested by\nsqueezing a handful into a ball. It should hold together well, but crumble when\nlightly squeezed. <\/p>\n\n\n\n Storage<\/strong><\/p>\n\n\n\n Sowing mixes should be made\nas needed, as they dry out and deteriorate if stored for more than a few weeks.\nFertilizers in the mix may start to break down and release ammonium, which can\ndamage seeds and seedlings. It may also get infected by pests and various\npathogens. Ideally you will store all of your ingredients in enclosed bins with\nthe appropriate moisture content (and labels).<\/p>\n\n\n\n Common ingredients<\/strong><\/p>\n\n\n\n Compost<\/strong><\/p>\n\n\n\n Compost is the natural\nmedium for seed germination, so well rotted compost is the basic ingredient in\nmany mixes. It\u2019s already pasteurized (if made properly), easily available, rich\nin nutrients, free of weed seeds, has a neutral pH, aids in water retention and\ndrainage and can help suppress damping off. It is also cheaper than other\ningredients, or free if you make your own. It isn\u2019t widely used in commercial\nsowing mixes because it is too variable and unpredictable and not sterile\nenough.<\/p>\n\n\n\n Finely sifted compost can be\nused as a substitute for peat in sowing mixes, though it contains a lot more\nnutrients. It\u2019s a good idea to sift and bag some compost in fall (write the\ndate on your calendar), so it is ready for use in late winter, without having\nto mess around in the cold. If you aren\u2019t that organized, then at least keep\nthe pile covered (it should be anyway) to prevent leaching and make sure it\nstays dry enough to use.<\/p>\n\n\n\n Many gardeners make a\nspecial compost pile for sowing mixes, adding extra nutrients and turning it\nseveral times, to make sure it is thoroughly heated and broken down. Ideally\nthis pile should be left under cover to age for 1 – 2 years before use.<\/p>\n\n\n\n Seed sowing mixes may\ncontain up to 1\/3 compost, while potting mixes may be as much as half compost\n(it is a good source of nutrients. <\/p>\n\n\n\n Soil<\/strong><\/p>\n\n\n\n For many years, the trend in\nconventional growing has been toward soilless mixes. A major reason for this is\nconcern about soil borne plant diseases and the excessive density of mixes\nwhere soil is a dominant ingredient. Soil is also heavy which adds to shipping\ncosts.<\/p>\n\n\n\n Soil is still used in many\nmixes, as it supplies nutrients and provides support. Use the best soil in your\ngarden; a good medium loam (not too much clay or sand) with lots of organic\nmatter and not too many weed seeds is the best. Some gardeners sterilize or\npasteurize their soil, but it isn\u2019t really necessary if you use good growing\ntechniques (I have never worried about the potential for infecting the\nseedlings with soil borne diseases). <\/p>\n\n\n\n Sharp sand<\/strong><\/p>\n\n\n\n Sand makes a mix more porous\nand improves drainage, but doesn\u2019t affect ph or contain nutrients. It is\ncheaper than any other drainage promoting material. It makes a mix quite heavy,\nwhich can be a drawback in some situations (such as for shipping plants). There\nis quite a lot of variation in sand, some types being much more suitable than\nothers. The best types are quite coarse, with some large \u215b<\/strong>\u02dd diameter\ngrains (such as number 2 builders sand). Beach sand is too salty, river sand is\noften too smooth and fine, as it masons sand. These fine sands tend to fill in\nthe pore spaces so don\u2019t work so well.<\/p>\n\n\n\n Composted manure<\/strong><\/p>\n\n\n\n This is a good source of\norganic matter and nutrients and can be used as a substitute for compost if\nthat is unavailable. Make sure it has been composted properly, otherwise it may\nbe full of weed seeds and other problems.<\/p>\n\n\n\n Worm castings<\/strong><\/p>\n\n\n\n If you have worm bins (you\nshould), these are a wonderful source of nutrients for the various mixes. See Composting<\/strong> <\/strong>for more on this.<\/p>\n\n\n\n Peat<\/strong><\/p>\n\n\n\n Sphagnum peat moss is widely\nused in sowing mixes, particularly the soilless types. It has several\nproperties that make it useful for sowing mixes. Most importantly it holds a\nlot of water, so increases the water retentive qualities of a mix. It has a\ncoarse structure that helps to give good aeration. It is also light, fairly\nsterile, holds on to nutrients and is free of weed seeds, insect pests and\ntoxic contaminants. It is also relatively inexpensive.<\/p>\n\n\n\n Peat is rather acidic (pH\n3.5 – 5.0), so ground limestone is often added to raise the pH up to 5.0 or\n6.0. Use approximately 2 tablespoons of lime per shovel of peat (4 ounces of\nlime will raise 8 gallons of peat 1 pH point).<\/p>\n\n\n\n I have\nalready discussed the ecological implications of using peat moss (see Fertilizers<\/strong>) and you may want to\navoid it altogether.<\/p>\n\n\n\n Live sphagnum peat may\ncontain the spores of a disease causing fungus (Sporotrichum Schenkii<\/em>),\nbut this isn\u2019t an issue with peat moss.<\/p>\n\n\n\n Coir<\/strong><\/p>\n\n\n\n This is made from the fibers\nthat surround coconuts and was once widely used in horticulture. It is becoming\npopular again in Europe because it is a good peat substitute. It is quite\nsimilar to peat moss, but less acidic (pH 5.5 – 6.8), holds more water and is\nmore durable. It works well, but is more expensive than peat moss because it\nmust be transported from the tropics, which seems like a waste of energy to me.\nIf you don\u2019t want to use peat there are other suitable alternatives (such as\nleaf mold).<\/p>\n\n\n\n Leaf mold<\/strong><\/p>\n\n\n\n Leaf mold is a very useful\ningredient for soil mixes. It is similar to peat moss in that provides a mix\nwith good aeration and helps it to hold water. Unlike peat it contains some\nnutrients (especially Ca, Mg and P), is a renewable resource, easily available\nand usually free.<\/p>\n\n\n\n You may be able to obtain\nalready decomposed leaf mold from deciduous woods. Be cautious when using it\nthough, as it\u2019s often very acidic and can sometimes actually inhibit seedling\ngrowth. Before using it in quantity you might want to experiment to see if it\nhas any detrimental effect. You will probably have to add lime to it to raise\nits pH.<\/p>\n\n\n\n It is much better to make\nyour own leaf mold, using the leaves of deciduous trees, especially oaks. Don\u2019t\nmake it from evergreens (either broadleaves or conifers) as they contain toxins\nthat can inhibit plant growth. See Composting<\/strong> <\/strong>for more on making leaf mold.<\/p>\n\n\n\n Turf loam<\/strong><\/p>\n\n\n\n Turf loam is made from\ndecomposed turf and was commonly used for starting seeds before the widespread\nuse of peat. It is a good source of organic matter and is also high in plant\nnutrients. It is made by leaving grass sod to decompose for 6 – 12 months. It\nis then shredded and sifted before use (see Composting<\/strong> <\/strong>for more on this).<\/p>\n\n\n\n Vermiculite<\/strong><\/p>\n\n\n\n Vermiculite is hydrated\nlaminar magnesium-aluminum-iron silicate and when heated to almost 2000\u00b0F, it\npuffs up like popcorn to 20 times its original volume. It holds up to 20 times\nits own weight in water and is added to sowing mixes to improve water retention\nand aeration. It contains some calcium, magnesium and potassium, has a neutral\npH and its C.E.C. is sufficiently high at 100-150 meq to hold some nutrients.\nThe coarser granular vermiculite is preferred for sowing mixes, because it\ndoesn\u2019t compact as much as the finer types.<\/p>\n\n\n\n There are drawbacks to\nvermiculite; it is quite expensive, it must be mined, is energy intensive to\nproduce (hence not very sustainable) and sometimes contains asbestos. Because\nof this it is very important to avoid breathing the dust, by wetting it\nimmediately. In keeping with my vow to not buy things I don\u2019t need, I don\u2019t use\nvermiculite (or perlite).<\/p>\n\n\n\n Perlite<\/strong><\/p>\n\n\n\n Perlite is made by heating\nvolcanic silica up to 1400\u00b0F, until internal moisture causes it to puff up like\npopcorn. It is often added to mixes because it is light, sterile and improves\nthe drainage and aeration of a mix.<\/p>\n\n\n\n Perlite doesn\u2019t contain any\nnutrients (but may contain toxic boron, aluminum and sodium), its dust is\nharmful to the lungs, its production is quite energy intensive and doesn\u2019t\nreally do anything that sand doesn\u2019t.<\/p>\n\n\n\n Perlite is a volcanic rock\nthat is heated and expanded to become a lightweight white material. It is\nsterile and has a neutral pH. When added to a soil mix, perlite can increase\nair space and improve water drainage. It is a hard material that does not break\napart easily. Perlite pieces create tiny air tunnels that allow water and air\nto flow freely to the roots. Perlite will hold from three to four times its\nweight in water, yet will not become soggy. It is much lighter than, and can be\nused instead of sand<\/p>\n\n\n\n Lime <\/strong>This is used to neutralize acid ingredients such as peat moss.\nDolomitic lime is preferred as it contains magnesium as well as calcium. See pH adjustment<\/strong> for more on this.<\/p>\n\n\n\n Fertilizer <\/strong><\/p>\n\n\n\n A small quantity of powdered\nfertilizer is often added to mixes to increase their nutrient content (mix with\na little sand and incorporate thoroughly). Use equal parts of blood meal,\ngreensand and rock phosphate and about half as much kelp powder.<\/p>\n","protected":false},"excerpt":{"rendered":"Soil based mixes:<\/strong>
1 part garden soil (or 2 parts) \u00a0
1 part sharp sand \u00a0
1 part compost or leaf mold or peat moss \u00a0 \u00a0
2 parts soil \u00a0
1 part leaf mold \u00a0
1 part compost \u00a0 \u00a0
5 parts compost \u00a0
4 parts soil \u00a0
1 part sand \u00a0
1 part leaf mold or peat moss \u00a0 \u00a0
2 parts soil \u00a0
1 part leaf mold \u00a0
1 part compost \u00a0 \u00a0 \u00a0 \u00a0
Soil-less mixes<\/strong> Some gardeners prefer these because they are lighter and less likely to contain damping off fungi and weed seeds. \u00a0
1 part vermiculite \u00a0
1 part milled Sphagnum moss \u00a0
1 part compost \/ leaf mold \u00a0 \u00a0
2 parts turf loam \u00a0
1 part peat \u00a0
1 part coarse sand \u00a0 <\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n![\"\"](\"https:\/\/greenmanpublishing.com\/wp-content\/uploads\/2020\/04\/sowing-mix-2.jpg\")
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