Sowing Methods for Vegetables
The commonest form of sowing outdoors is in straight drills – virtually slits made in thewith the blade of a hoe or trowel. Seed is sown in the bottom of the drill and covered with soil. The depth of sowing depends on the size of the seed. Small seeds like and carrots should be about 1 cm (1/2in) deep, and about 2.5cm (1in), beans about 4cm (1-1/2in).
What matters most is the condition of the soil. Seeds germinate best in warm moist soil. In wet conditions they are liable to rot and be attacked byin the soil, though seed dressings can be used to counter these problems. In very dry soil they simply fail to germinate.
Steps can be taken to overcome hostile conditions. If the soil is very wet, the drill can either be lined with peat or sowing, or covered with cloches for a day or two to warm it up before sowing. If the soil is very dry, take out the drill, water only the bottom of the drill until it is almost muddy, sow the seed and cover it with dry soil. This acts as a mulch and prevents the moisture evaporating — an invaluable technique for summer sowings
The golden rule is to sow thinly. If the seeds are large enough for individual handling, sow them at least 1-2.5cm (½—1in) apart, or ‘station sow’ in little groups of three or four at ‘stations’ a few inches apart; these will be much easier to thin than a continuous row. Nothing is ever gained by thick sowing; overcrowdedare prone to attack by pests and diseases and never develop satisfactorily.
Large seeds like peas and beans are sometimes sown individually in holes made with a dibber or stick. Just make sure the seed touches the bottom of the hole and is not suspended in a pocket of air. Some large seeds such asor sweetcorn can be sown direct and covered with a jam jar until they germinate. The jar acts as a miniature cloche.
An old-fashioned method of sowing which deserves a comeback is broadcasting. After preparing the seedbed, seed is simply scattered evenly and thinly on the surface. It is then raked over first in one direction and then at right angles to the first direction. This is a useful way of sowing early carrots and, and for the cut-and-come-again seedling crops such as , Mediterranean rocket, lettuce and which are grown for salads.
As with any sowing, germination is encouraged by covering the seedbed with sheets of newspaper or polythene film, which helps to maintain a moist atmosphere. Unless perforated plastic is used, the cover must be removed as soon as any seedlings appear, or they will become white and drawn.
Virtues of Thinning
Thinning, the removal of surplus seedlings, is an important — albeit rather tedious — gardening operation. Ideally, you should sow so thinly that thinning is unnecessary: in practice this rarely happens. Thinning is best done in stages, starting as soon as the seedlings are large enough to handle, and thinning each time so that each seedling stands just clear of its neighbour. The final distance depends on the vegetable: radishes need be only 2.5cm (1in) apart,12cm (5in), lettuces 22-25cm (9-10in). Instead of uprooting the unwanted seedlings, they can be nipped off at the base, which minimizes the disturbance to the remaining seedlings. All thinnings should be removed immediately, as their characteristic smell attracts the plant’s pests. The carrot root fly is a classic example, homing in on carrots which have been thinned.
Where seedlings are being uprooted, do this when the ground is moist, or water the soil beforehand; afterwards, firm the soil around the base of the remaining seedlings. Similarly, before digging up plants for transplanting, water the seedbed if dry, to minimize disturbance to the roots.
A high proportion of failures with vegetables can be traced to that notoriously vulnerable stage between seed and seedling. We fail to get good results because we sow too early (those fatal itchy fingers that gardeners get in spring), too thickly, when it’s too cold, too wet or too dry — mistakes all compounded by subsequently thinning or transplanting too late.
The Block Revolution
The relatively new technique of sowing individual seeds in small blocks of soil or peat compost overcomes many germination and early growth problems, and is ideal for anyone who wants relatively small numbers of vegetable plants. It is a simple alternative to the traditional system of raising prize vegetable specimens in small pots, guaranteeing plants the best conditions during their most vulnerable stages and in unfavourable conditions.
The blocks are compact cubes, measuring about 4cm (1-1/2in) each way, with a small hole in the top in which the seed is sown. They are best made of peat blocking compost (a commercially prepared potting compost with an added adhesive agent), but peat-based compost or soil-based sowing compost or basic potting compost can be used. Blocks are pressed from moistened compost using a special tool. Professional growers use multiple blockers, but there is a type available to amateurs that makes one block at a time. Stand the blocks side by side in a standard seed tray.
Usually one seed is sown in each block, but several seeds can be sown to allow for low germination, and later thinned to one per block. Large and pelleted seeds are easily sown by hand; smaller seeds can be pushed carefully off a piece of paper, or picked up on a paintbrush or label and dropped singly into the block. The seed is covered with soil from the edge of the hole.
Each seedling grows rapidly in its own block, unimpeded by competition, developing a vigorous root system which permeates the whole block. No thinning is necessary. When the seedling shows signs of outgrowing its block, the whole seedling is then planted out as one unit; harden off first if necessary. There is no transplanting shock, nor the damage often done by tearing apart the intertwined root systems of plants raised in a seed tray. The protective nature of the block means that planting can be successfully carried out in conditions which would otherwise be considered too wet or too dry.
Blocking is the most flexible of systems. One seed tray holding forty blocks could, for example, be used to raise tenplants, five brussels sprout plants, twenty lettuces, five and ten bedding plants or even , which have a very high death rate when sown direct.
If you cannot get the proper equipment, improvise. Sow in a seed tray, space the seeds about 4cm (1-1/2in) apart and with a knife divide the compost into squares.