Cucumber

Cucumis sativus

Introduction: This tropical species is thought to have come from India or thereabouts and has a very long history of cultivation there. It reached Europe early enough to have been widely grown by the time of the Romans.

Nowadays cucumbers are one of the most popular home garden vegetables. This isn’t surprising as they are tasty, productive and have an extended harvest season (though they do take up quite a bit of space).

Nutritional content: Cucumbers are a good source of water (96%). They also contain some vitamin C, potassium and antioxidants. As a source of energy they contain 68 calories per pound (not exactly rocket fuel).

Climate: Cucumber is a tropical plant and needs warm (70 – 80°F) sunny days, mild nights and plenty of water for best growth. They can’t stand any frost at all.

Ease of growing: Like the related squash the cucumber is a pretty easy plant to grow, so long as it gets good soil and warm weather (and pests and diseases don’t get too bad ).

Crop value: Cucumber rates close to the bottom on the self-sufficiency scale. It takes quite a bit of room to grow and is very low in nutritional value (you could starve to death growing and eating cucumbers).

Soil

pH 6.0 (6.8 – 7.0) 7.5

Cucumbers grow rapidly once established and to sustain their high level of growth they need a rich soil. It should be loose, moisture retentive and well-drained, with lots of organic matter. Raised beds are good because they help the soil warm up quickly and provide good drainage.

Soil preparation: Incorporate 2˝ of compost or aged manure into the top 6˝ of soil. Add lime if the soil is acidic, as they don’t like a low pH. They don’t like salt either, so watch what kind of manure you use. 

In cool areas with plenty of rain, cucumbers are often grown in raised hills, ridges or beds, as this helps the soil to warm up faster. This doesn’t work so well in hot dry areas though, as they tend to dry out more quickly and so need more irrigation.

Planning

Where: For maximum production cucumbers need full sun (at least 8 hours daily). They can grow well enough with light shade, but will be less productive.

Don’t plant cucumbers where any of the Cucurbits (cucumber, melon or squash) have grown within the last three years.

When: Cucumbers are native to the tropics and absolutely must have warm soil (60°F minimum – 70°F better) for good germination and growth. Consequently they are among the last crops to be planted out in spring. Most varieties fruit better in short days, so tend to be more productive later in the summer.

Cucurbits in general (squash, melons, cucumbers) are all easy to start from seed, though they don’t like transplanting.

About Cucumbers   Seed facts Germ temp: 60 (65 – 75) 105°F Germination time: 3 – 10 days 13 days / 59°F 6 days / 68°F 4 days / 77°F 3 days / 86°F * Optimum 3 days / 95°F Germination percentage: 80%+ Viability: 2 – 5 years Weeks to grow transplants: 3 – 4   Planning facts Hardiness: Tender Growing temp: 60 (70 – 80) 90°F Plants per person: 1 Plants per sq ft: ¾   Planting: Start: On last frost date Plant out: 3 – 4 wks after last frost Direct sow: 2 – 4 wks after last frost.   Harvest facts Days to harvest: 70 – 100 days Harvest period: 8 – 12 weeks Yield per plant: 4 lb (10 – 20 fruit) Yield per sq ft: 3 lb sq ft

If your growing season is long you can start them outside 2 – 4 weeks after the last frost date (or whenever the soil reaches 60°F).

If the growing season is short then start the seeds inside on the last frost date (they grow fast) and plant out 3 – 4 weeks later. Don’t start them too early, as you can’t put them out until the soil is warm and if they sit inside too long, they may get root bound.

Don’t be in too much of a hurry, as plants set out at the right time will usually outgrow those planted too early. If necessary you can speed up soil warming in spring by using black plastic mulch or cloches.

Support: The bush cucumbers are quite compact, but the vining types take up a considerable amount of space if left to sprawl across the ground. Fortunately they are good climbers and will be perfectly happy growing vertically. Trellised plants may take up only one tenth of the bed space of unsupported ones.

Trellising can also increase yields by as much as 100%, because fewer fruits are lost to rot, disease or slugs and there is more light for photosynthesis. Fruits are also straighter and cleaner.

If building a trellis seems like a good idea, but too much work, you may be able to plant them along a wire fence. You can also use cages of 6˝ mesh steel reinforcing wire, 3 ft in diameter and 6 ft high. These can work well, though the plants may eventually outgrow them. These cages can even be covered with plastic to protect the young plants from late frost. You can also open these out to create a wire tunnel, which can also be covered in plastic in cold weather.

Many kinds of supports have been used for cucumbers, including fencing wire, nylon netting and bamboo canes. Be creative, but make sure it is strong enough to support the weight of a fruiting crop (and wind and rain), you don’t want it to collapse.

If you are going to support your cucumbers, you should set it up before planting. This will minimize disturbance to the young plants.

No support: Supporting the vines up in the air isn’t always a good idea. In hot, dry areas it is better to leave the plants close to the ground, where they can create their own little humid microclimate and so lose water less rapidly.

Planting

Transplants

Starting inside: Early cucumbers are usually started indoors, because the soil outside may not be warm enough for good germination (even though the air may be warm enough for their growth). They dislike transplanting, so are usually started in individual 3 or 4˝ containers, 2 seeds to a pot (later thinned to the best one). Don’t use smaller containers, as the seedlings grow so quickly you will soon have to re-pot them.

Planting out: Dig a hole and half fill it with a couple of handfuls of compost, then plant out the seedlings up to their first true leaves. Water immediately after planting. If the weather turns cold after planting you should cover them with cloches or row covers.

Direct sowing: Once the soil has warmed up it is simpler to sow cucumbers directly in the soil 2 – 3˝ deep. In good conditions they grow very quickly and will often catch up with transplants, even though they were started several weeks later.

In dry conditions you might want to soak the seed overnight before planting to hasten germination. You can even pre-germinate them (this is fairly straightforward because they are so big).

Planting methods

Beds: When growing in intensive beds, the compact bush varieties work best. Plant them in two alternate rows down the bed. You may want to interplant a fast growing crop at the same time, to take advantage of the temporarily vacant space.

You can use vine cucumbers in a bed too, but you will have to give them support so they can grow vertically.

Hills: Vine cucumbers were traditionally planted in hills. You can do this by digging a large hole 12˝ in diameter and 12˝ deep (you can line this with gopher wire if necessary). Half fill this hole with compost and then return the soil to the hole. The result is a slightly raised mound that warms up quickly and provides good drainage. Several seeds (5 to 6) are then sown on top of the mound. When these have several leaves they are thinned to the best 2 or 3 plants.

The disadvantage of raised hills is that they dry out quickly, so don’t work so well in dry climates. In such circumstances you can flatten the “hill” until it is flat. In extreme cases you might even make it into a slight depression (an anti-hill).

Ridges: In the cool climate of Britain outdoor cucumbers are often sown on raised ridges of soil, as these warm up better. To make a ridge you dig a trench and fill it with compost or aged manure and then replace the soil to form a ridge. You then plant your cucumbers in a row along it.

Spacing: There are quite a lot of options for spacing, depending upon the type of cucumber you grow and how you grow them:

Intensive bed spacing varies from 18 – 24˝ apart, depending upon the soil and the variety. If growing in two parallel rows you might have 24˝ between the plants and rows.

Trellised vine cucumbers can be grown 12˝ apart in the row, with 24 – 36˝ between the rows.

Cucumber hills are planted 36˝ apart, with 2 or 3 plants in each hill.

Plants in rows should be 24 – 30˝ apart, with 48 – 72˝ between the rows.

Succession sow: Make another sowing 4 – 6 weeks after the first one (and if your growing season is long maybe another a month or so after that). You then have vigorous young plants to take over as the older ones start to decline in productivity.

Care

Cucumbers are pretty vigorous plants and don’t usually require a lot of attention.

Watering: Cucumbers are mainly composed of water and for best growth you should keep the soil evenly moist, but not wet, at all times. This is particularly important when they start producing fruit. Give them a minimum of 1˝ water per week. Ideally this should be lukewarm (70°F), so it doesn’t shock the plants or cool the soil significantly.

The best way to water cucumbers is with a drip system or soaker hose. This keeps the leaves dry and so reduces the chance of disease problems. If you must use a sprinkler do it in the morning, or early evening, so the leaves have a chance to dry quickly. You don’t want them to stay wet all night.

Mulch: This is beneficial to conserve moisture and keep weeds under control (as an added benefit it also keeps the fruit clean). The soil must be warm before you put this on though, as mulch insulates the soil and prevents it from warming up.

A living mulch of annual clover can work well with cucumbers.

Fertilization: When the seedlings have recovered from transplanting, give them a liquid feed of liquid kelp or compost tea, to give them a boost. If your soil isn’t very fertile, then continue to feed them every 2 – 3 weeks (or at least after the first flowers appear).

Pruning: In some circumstances you might want to pinch out the growing tip of the young plant to encourage branching. Some people pinch them back twice, so they produce four growing tips.

Pollination: Cucumbers are monoecious (they produce male and female flowers on the same plant) and the first few flowers to appear are usually males. These don’t bear fruit of course.

Female flowers are easily recognized by the tiny “cucumber” at the back of the petals. These appear soon after the first males and will to bear fruit if pollinated successfully. If the weather is cool this may not happen, in which case they will simply shrivel and drop off. Apparently cold weather encourages the production of male flowers, while warm weather encourages female flowers.

If your plants aren’t setting fruit you could try hand-pollinating some of the female flowers (seed savers do it all the time). This isn’t usually necessary though, just be patient and they should start to produce eventually.

Problems

Pests and diseases: I have generally found cucumbers to be fairly free of pests, though they do have a few serious ones.

Cucumber beetles: This is the biggest problem when growing cucumbers (no surprise really, with a name like that). This pest doesn’t just eat the plants (which is bad enough), but can also spread bacterial wilt disease. Row covers will work until the plants get too big, Another approach is to plant blue hubbard squash nearby, as these will attract the beetles away from the cucumber (in theory at least).

Other pests: Squash bugs, aphids, pickle worms, squash vine borers.

Diseases: Powdery and downy mildew are the commonest diseases of cucumbers. Keep the leaves of plants dry and make sure there is good air circulation. Other diseases include alternaria blight, angular leaf spot, anthracnose, mosaic virus and bacterial wilt. Some varieties are resistant to some of these diseases.

Bitterness: Bitterness in cucumbers is caused by chemicals known as cucurbitacins and is partly genetic, though high temperature and lack of water can make things worse.

The easiest way to avoid bitter cucumbers is to plant a non-bitter variety that is low in cucurbitacins. An added benefit of these is that they may be less attractive to cucumber beetles. You should also make sure the plants have plenty of water, especially in hot weather.

Harvesting

When: The fruit will be ready for harvest 15 – 18 days after pollination (which is roughly 2 months after planting). The first fruits are usually quite small, simply because the plants themselves aren’t very big.

Once the plants start producing, you should check them every 2 – 3 days and harvest any fruits that are ready. The plants regulate the number of fruits they have growing, so if they are already holding a lot, they won’t produce many new ones.

For maximum yield you should harvest the fruits just before they reach full size. You can gather them when smaller than this, but you won’t get as much food. They grow very quickly, doubling in size in 24 hours, so don’t leave the fruits too long, or they will start to develop hard seeds and the skin will toughen. Definitely don’t allow any fruits to mature on the vine, as this can stop the plant producing altogether. Pick the fruits regularly, even if you just throw them at a wall.

If you want small fruits for pickling, you can harvest ordinary cucumbers while they are still small, but the specially bred pickling varieties will be much more productive.

How: It’s better to cut the fruit from the vine, rather than pulling it off. The stem is quite tough and it’s easy to break part of the vine accidentally. Ideally you should leave a short section of stem on each fruit, to prevent moisture loss. Brush any small spines off of the fruit with your hands.

Storage: Cucumbers are at their best when eaten immediately after picking. They are very perishable, but will keep for a week or so if stored in a cool place (40 – 50°F). Don’t keep them in the fridge. For longer term storage they are often pickled. I don’t advise trying to dry them as they are 96% water!

Seed saving: Cucumbers are cross-pollinated by bees, so must either be isolated by 1000 yards or hand pollinated. Hand pollination is fairly straightforward because the flowers are so large. It is done in the same way as for Squash (see Squash). Take seed from 5 of the best and most typical plants to avoid inbreeding depression.

If you are saving seed, the fruit must be allowed to mature properly. It will turn yellow and start to wither when fully ripe. Separate the seeds from the pulp and ferment them for a couple of days in the same

way as you would for tomato.

Finally separate the cleaned seeds from the fermented mush and dry them thoroughly. Ideally they should have a moisture content of around 6% for storage. Be aware that a number of diseases can be seed borne.

Unusual growing ideas:

Ornamentals: The vining types are vigorous climbers and can be used to cover a wire fence or trellis and turn it into a temporary and quite ornamental screen. They are such good climbers they can even be trained over an arbor to provide summer shade.

Containers: The bush varieties do quite well in containers, so long as you keep them well watered.

Varieties:

A lot of breeding work has gone into the cucumber and the result is a lot of variation. The shape of the fruit varies considerably, from foot long green ones to tennis ball sized white or yellow ones. Some varieties are resistant to specific diseases. There are also gynoecious varieties that produce all female flowers and are self-fertilizing (parthenocarpic) for growing in the greenhouse.

Bush cucumbers are favored in small gardens because of their compact habit, though they aren’t generally as productive as the vine types.

Vining cucumbers are often preferred in warm moist climates as they get better air circulation, so are less

vulnerable to disease. They may suffer

more from sunburn however (you win some you lose some).

When choosing a cucumber remember that bitterness is partly genetic. If you have had a problem with this in the past then be sure to choose a non- bitter type, such as one of these listed below.

Pickling: These produce large numbers of small, light green fruits, ideal for pickling (what else?)

Parisian Pickling: This famous heirloom is not only outstanding for pickles, but is also good for fresh eating if it gets bigger.

Slicing: These produce the large dark green cucumbers you see in markets. They tend to be productive and disease resistant.

Diva F1: Sometimes said to be the best flavored cucumber. It produces all-female flowers that don’t require a pollinator. 

Persian cucumber – Early and productive, the thin skinned fruits are never bitter.

Boothby’s Blonde – The light colored fruit are non-bitter. This is sometimes said to be the best cucumber.

Sweet Slice, Carmen, Country Fair are all non-bitter.

Long:

Telegraph Improved – Old English heirloom, long, sweet fruits.

Yamato – Produces an abundance of long fruit (to 20˝). Can also be pickled.

Japanese climbing – The long, non-bitter fruits are produced abundantly. Often said to be one of the best cucumbers.

Satsuki Madori – Vigorous, productive and produces delicious non-bitter fruit. Sometimes said to be the best cucumber.

Round:

Crystal Apple – This Australian heirloom is round, sweet and white.

Lemon Cucumber – Very similar to the above, but light yellow.

Kitchen use

Cucumbers are almost always eaten raw of course.

Pickles   3 lb cucumbers (3 – 4˝) 8 cups water ¼ cup cider vinegar ⅓ cup salt 8 garlic cloves (peeled) 2 small fresh hot peppers 2 tbsp whole mustard seeds 2 tsp celery seeds 1 tsp turmeric 1 tsp freshly ground black pepper 6 to 8 seed heads dill   Thoroughly mix the vinegar, spices, garlic cloves, dill heads and salt (it should all dissolve) with the water and pour over the cucumbers into a large ceramic bowl. Put a plate over the bowl to push the cucumbers under the surface. Cover with a cloth and leave for 48 hours. Finally put the pickles into jars with a clove of garlic and cover with brine (remove the dill). They will keep in the fridge for about 3 months.