Sowing Seeds In a Greenhouse or Cold Frame
Given the protection of a greenhouse or cold frame, seeds can be sown under glass in controlled conditions. If you do not possess either of these, a sunny windowsill indoors can be used for the purpose. Seed can be sown in pots, boxes, seed-trays or seed-pans, provided that they are clean and sterile. Containers that have been used previously should be sterilized with a 2% solution of formaldehyde (from gardening shops) or a proprietary product. The containers should stand on a bed of ashes in the greenhouse or frame or on the greenhouse shelving. Pots and seed-pans should have a few broken crocks placed over theirholes so that these do not become blocked.
Choose a suitable medium for sowing, such as John Innes No. 1 seed compost or one of the proprietary peat-based seed composts. Boxes can be lined with a thin layer of sphagnum moss.
The compost should be moistened and firmed before the seed is sown and the seed should be covered with a fine layer of sharp sand as a precaution againstdisease. Containers should be covered with a sheet of glass or, where pots are used, they can be sealed in a polythene bag until the seed germinates. The bag method is particularly good since there is no need to wipe the condensation off the glass every day.
Much of the time and work taken up by sowing and planting out can be avoided if you sow your seed in pots made of compressed peat. These are filled with a suitable sowing compost and one or two seeds are sown in each. The seedlings can then remain in the pots until it is time for them to be moved to their permanent quarters where they are planted out, still in the pots. The peat pots disintegrate gradually in the, and because of their composition, root growth is encouraged after planting out. Individual peat pots are obtainable for larger seeds such as peas, beans, and sweet peas. For smaller seeds, you can get blocks of small pots that fit into a standard sized tray; these can easily be broken into separate units at planting time.
Equally useful, and more economical after the initial outlay for equipment, are the soil blocks that you make yourself with a pot press. The press is filled with moist compost, which is then pushed out on to a seed box or tray in neat 4-5 cm (1-1/2 – 2in) cubes. As the roots of the seedlings grow, they bind the soil together, so that the blocks can be planted out at the appropriate time without damaging the delicate roots.
If you have a greenhouse, a propagator can be useful for seeds that are difficult to germinate without artificial heat, saving waste of time and disappointment. It can also be used effectively in a garden room or on a sunny windowsill. The object of a propagator is to provide a correct and even temperature and degree of humidity for seed germination.
As well as simplifying seed-raising, propagators also provide an easy and trouble-free way of increasing stocks of plants from cuttings. Their controlled conditions of temperature and humidity do away with most of the routine work involved when cuttings are struck under glass in the usual way. By incorporating a thermostat and controlled mist spraying, the entire process can be made almost entirely automatic.