Growing Cucumbers Indoors
Cucumbers are not the easiest of vegetables to grow, but if you choose the right varieties to start with and give them the regular care they need, you can produce a successful crop at your first attempt.
As well as the usual salad uses, there are various recipes in whichcan be included; they can even be stuffed and cooked. They are a more versatile vegetable than is sometimes appreciated, and are attractive plants to grow.
Cucumbers are divided into two main groups; greenhouse types and the outdoor varieties, also called ‘ridge’ cucumbers. The latter are not suitable for container-growing, requiring a large area and a lot of specialized attention and feeding. You should therefore confine your choice to the various greenhouse cultivars, which do not necessarily have to be grown in a greenhouse and can be successfully cultivated on a sunny windowsill indoors. The all-female hybrids need no pollinating and many of these types, although comparatively small and compact plants, produce cucumbers of adequate size for most culinary requirements.
Cucumbers for indoor growing
The smallest cultivar, Fembaby, is an F1 hybrid often called the ‘windowsill cucumber’. It has a curious history: one man spent eight years of his life breeding this hybrid in an effort to produce a cucumber small enough to provide supermarkets with whole cucumbers, rather than the halved large cucumbers commonly on sale. In fact, it turned out that customers preferred to buy the large cucumbers sliced in half: but horticulturists discovered that the new small variety was disease-resistant, cold-tolerant and compact in growth – ideal for growers without a greenhouse, who could grow it at home indoors at any window with a sunny aspect. Being an all-female hybrid, the plant does not need pollinating. In other words, it is a trouble-free cucumber for the indoor gardener, so Fembaby has now become a popular choice.
Fembaby produces the smallest cucumbers of any cultivar, averaging 8in (20cm). These are straight and well-flavoured. Other cultivars grow into taller plants producing bigger cucumbers. I can recommend Telegraph Improved, an old favourite which has stood the test of time for indoor and outdoor growing. It is an all-round cultivar, a prolific cropper, and needs no pollination, but male flowers must be removed as they appear, as if they are allowed to pollinate the female flowers on the same plant, the cucumbers will be bitter.
Burpless Tasty Green F1 hybrid is a comparatively recent introduction, producing cucumbers 8-10in (20-25cm) long. This is an all-female hybrid which will not produce male flowers. A somewhat similar cultivar, but producing larger fruits, is Sweet Success F1 hybrid. The cucumbers are seedless and have a very sweet flavour. This strain is particularly disease-resistant and the cucumbers reach an average of 14in (35cm). It is also a faster-maturing variety; when sown in late spring, the plants can be fruiting within eight weeks of the youngshowing. Another prolific cropper is Conqueror, not a hybrid, so male flowers must be removed. These varieties are all equally at home indoors or out.
Sowing and germination
All these cucumbers can be grown quite successfully in ordinary plant pots, a 5in (12.5cm) pot being quite big enough for growing Fembaby and an 8in (20cm) pot for the larger cultivars.
Spring is the best time to sow seed, but some cultivars may be sown at any time of year, provided that they have a sufficiently high initial temperature to ensure germination: 75°F (24°C) is not too high, and the night temperature must not drop below 60°F (15°C). If you can provide these conditions, winter sowings of cucumbers are a possibility; if not, wait until spring to start your crop.
My own method is to sow one seed per 3in (8cm) pot, the seed sown on edge 1/2in (1cm) deep. Cucumbers require a very rich and fertile.
It is best to make your own potting medium, using one part loam, one part peat, one part humus, and one part well-rotted horse manure. The humus can be obtained by gathering dried leaves – oak, beech, sycamore, for example.
Failing this, use a commercial soil-based growing medium and mix in some humus, which you should be able to obtain from your garden centre or usual supplier in bags of varying quantities. Use equal proportions of soil and humus to produce a rich, open-textured and free-draining potting mixture.
A little lime is beneficial, but do not overdo it – a small pinch per pot is sufficient. A sprinkling of bone meal will do no harm – a half-teaspoonful per pot is more than enough. Moisten the potting mixture before sowing with a fine spray of tepid water. While the seeds are germinating, stand the pots in saucers or trays so that they can be watered from below as necessary.
There is another method which indoor gardeners can use, which you may prefer to pot-growing. The containers used are large wooden boxes with a few holes punched in the bottom for drainage. A fertile bed is built up in layers – strawy manure about 6in (15cm) deep for the bottom layer; on top of this some turf placed upside down; and the rest of the box filled with finely-sifted loam. The turf layer provides humus as the grass decays. This is a more demanding cultivation process, only suitable if you have plenty of space and want to produce a large crop.
As soon as the seedlings have appeared, move the pots to the lightest spot you can give them. A weak feed of very diluted fertilizer may be given fortnightly in these early stages. When the plants have produced four true leaves, after the initial appearance of the two seed leaves (cotyledons), transplant them to bigger pots – 5in (12.5cm) for all cultivars for the first re-potting and subsequently 8in (20cm) pots for all except Fembaby, which can stay in the smaller size.
Cucumbers are not the most resilient of plants, so when potting on you should use a method which causes minimum disturbance to the plants’ roots. Rather than pulling or levering the plant from the soil, turn the pot upside down with your hand spread over the surface of the potting mixture, the stem of the plant loosely supported between your fingers. Tap the bottom of the pot to loosen the entire soil ball and handle it carefully in transferring the plant to the larger pot size, to avoid bruising or crushing the more delicate roots.
Do not neglect the routine of watering, spraying and occasional feeding. Given warmth and moisture, the plants will develop well towards the stage when they produce their flowers and can then be encouraged to set fruit. Remember to remove any male flowers which appear on non-female hybrid cultivars, or the cucumbers will become misshapen and bitter.
Pests should not prove troublesome. The main pest of cucumbers is the red spider mite, but it is more likely to attack greenhouse-grown plants than those grown in containers indoors. It is to be avoided, however, by spraying the plants regularly with tepid water. Mites hate moist conditions, but the cucumbers thrive in a damp atmosphere. Be sure to spray your plants every day if you have a drought.
Supporting the plants
These small cucumber cultivars are, and they need to be allowed to spread naturally if they are to produce a heavy crop. Maturing plants require support to encourage the final stages of development and to help them bear the weight of the ripening fruit. The main stem should be tied to an upright support, but laterals (side shoots) may be allowed to trail or cascade downwards, tied to separate supports if preferred. The laterals are often given the additional support of canes tied horizontally to the main vertical stakes.
The alternative common method of growing cucumbers is to support all stems upright (using thinner canes for the laterals than for the main stem), and to pinch out the growing points of the laterals at the second joint (above the second pair of leaves). Sub-laterals, the side shoots which grow in turn from the laterals, should be pinched out at the first joint. This treatment encourages the plant to produce fruits rather than additional leaves. Any large, unfruitful, leafy stems which may obscure the light from the flower-bearing stems should be removed.
Spring-sown plants often produce fruit within seven or eight weeks, but some varieties take three to four months to develop the crop. Cut the cucumbers as soon as they are large enough; leaving them on the plants causes them to deteriorate quickly. The plants will usually produce further fruits after the first crop has been picked.