How to Sow Seeds: Gardening Techniques
Any discussion of seed sowing brings to mind the proverbial advice to those about to get married – don’t! It would be difficult to claim that raising plants from seed is labour-saving, since far less trouble would be involved if you bought them direct from a nurseryman, garden centre or market stall. However, the most economical and enjoyable way of stocking your garden is to grow at least some of the plants from seed, since the work is not physically demanding and brings a satisfying sense of achievement.
With the various routine procedures set out below, I have tried to include as many short cuts and labour-saving hints as possible for those who are prepared to ‘have a go’ at this rewarding task.
Annuals, biennials and perennials (see below for definitions) are all easily propagated from seed. A number of shrubs such as brooms, buddleias, heathers and eucalyptus can also be raised from seed, but it will take several years before they flower or make any real impact in the garden so that it would hardly be worth the effort for the small garden, where only limited numbers of such subjects are needed.
Annuals are plants that grow, flower and set their seed in a single season. Biennials are similar in habit, but do not bloom and make seed until their second season. Both annuals and biennials die off after their life cycle is completed. This is a factor that should be borne in mind if you are a busy gardener. To sidestep the work involved in annual replacements, you may prefer to concentrate on herbaceous perennials, which renew their growth from ground level yearly, or on shrubs, which are the labour-savers par excellence.
Both annuals and biennials fall into two categories – hardy and half-hardy. The former can be sown outdoors in spring or early summer and transplanted to their flowering positions as soon as the seedlings are large enough to handle easily. Alternatively, seed can be sown where the plants are to remain, the seedlings being progressively thinned until they are correctly spaced. This saves any transplanting and results in stronger, more vigorous plants. Examples of hardy annuals are annual, nigella, cornflowers and Virginian stock. Hardy biennials include foxgloves and Canterbury bells.
Half-hardy annuals are normally raised under glass, in heat, during spring and hardened off before being planted out where they are to flower.
However, from the labour-saving point of view, it is better to sow the seed outdoors, in situ, once frost danger is over. Depending on district and season, this is usually in late May or early June. The plants will come into flower some weeks later than those raised in heat, but they are often stronger and more pest and disease resistant. In addition, the work of tending them from the seedling to the flowering stage is much reduced. Half-hardy annuals include antirrhinums (snapdragons), asters, petunias and French marigolds. There are no common half-hardy biennials.
Hardy biennials, and perennials such as wallflowers that are treated as biennials for garden purposes, are sown outdoors in late spring or early summer. The usual procedure is to transplant the seedlings first to a nursery bed before putting them out in their flowering positions in autumn. If you want to cut down on work, however, they can go straight from the seedbed to their permanent situations. They will not be as bushy or vigorous as the twice-transplanted seedlings, so put them closer together than the recommended planting distances. Wallflowers, for example, should go in with their leaves practically touching, rather than at the normal planting distance of 30 cm (1ft).
For successful outdoor sowings, you must wait until thehas warmed up sufficiently in spring to allow the seed to germinate freely and as rapidly as possible. For this, seeds need both warmth and moisture. Sowing too early often means wasted effort, with the seeds germinating irregularly, slowly or not at all. Warming-up of the soil can be speeded up by placing cloches over it. By providing a more even temperature, cloches also cut down the risk of the seedlings suffering from damping-off disease (which is caused by a fungus that attacks the stems of the young plants, causing them to keel over and rot). Cloches are, therefore, time and labour-savers since they cut down on time and trouble spent on growing replacements.
There is no need to break your back when preparing a seedbed. Any weed free stretch of good garden soil will be suitable, with the surface firmed and raked down to a fine crumbly tilth before the seed is sown.
The depth at which you sow the seed is important, and it will vary according to the kind of seed and the type and condition of the soil. As a general rule, all seeds should be sown slightly deeper in light soils than in heavy ones. A good general yardstick is to sow the seed twice as deep as its diameter. Nowadays, most seed packets provide much useful information regarding the time and depth at which to sow as well as thinning distances.
Certain hardcoated seeds, such as sweet peas, lupins and broom, will germinate faster if their coats are chipped with a sharp penknife or razor blade. Alternatively, they can be soaked in water for 24 hours before sowing.
In recent years the use of pelleted seed has become increasingly popular, resulting in a considerable saving of time and labour where sowing and thinning are concerned. Only certain kinds of seed are subjected to this process – mainly the very small ones that are difficult both to handle and to sow thinly.
The compound used for the pellets is a type of clay, so that it is essential that the soil in which they are sown is kept moist until germination begins. If, on the other hand, the soil is too wet there is a danger that the pellet- ing material will smother the emerging seedling. Normally, however, it is only on exceptionally heavy wet clay soils that this difficulty is encountered. For really heavy clay soils many gardeners find it worthwhile to line the seed drills with peat or sifted compost. After sowing, water the seedbed lightly, using a watering-can fitted with a fine rose.