Tips for Propagation by Seed
Seed sowing in frames and borders
What has been said about the sowing of seed in pots, pans or boxes applies generally in the case of sowing seeds in frames, the seed being sown in many cases in the actual ground, although it can be sown in receptacles; follow the same principles of shade for a few days and regular watering thereafter.
No special conditions apply other than adequate preparation, checking its lime and nutrient content by analysis, a good firm seed bed and the avoidance of drying out. Seed can be sown in drills, or spaced out, or sown broadcast, as with brassicas, which can be merely scattered on the surface before either being covered with some riddled soil or pressed in with the back of a spade.
Weed control may be a problem in frames, necessitating sterilization either with chemicals or by heat, although weedkillers such as paraquat can be used on the delayed seed bed technique, ie. soil is prepared some weeks in advance of sowing and paraquat applied 2-3 days after sowing. Alternatively specific weedkillers, such as CIPC (commercially available only) for lettuce, can be applied.
The same general principles apply when sowing seeds direct in greenhouse borders.
Ancillary propagating equipment
Dibbers can be made with any convenient piece of stick 10-13cm (4-5in) in length and pointed at one end, or plastic dibbers can be purchased. Dibbers are used for space-sowing seed; marking holes for the insertion of cuttings; for pricking off, making the indentation necessary to receive the little plants; and either a dibber or tally can be used for easing young plants out of their pots or boxes.
A series of round or rectangular firmers with handles are invaluable where a lot of seed sowing is involved. Any handyman can make these up. A similar sort of item with nails or wooden pegs inserted is useful for pricking off on a large scale, being pressed into the prepared box to make the little holes to take the young plants. A fine-rosed watering can is an essential, as also are some trays for immersing the trays or pots when water is to be given from below. Seed sowers made of plastic are also available, although many gardeners prefer to use their fingers.
A professional gardener sowing many boxes of bedding plants every year will find a series of little measures extremely useful to measure the correct amount of seed per box. A series of fine sieves can be made from metal mesh material tacked on to wooden framework, or fine riddles can be purchased. Sheets of glass of various sizes for covering boxes are essential, unless plastic dome covers or bags are available for trays. For removing cuttings from plants use either a sharp thin knife or razor blade, preferably one-sided for safety or in a special holder.
Geraniums from Seed
Pricking off procedures
I is essential to move seedlings on or prick them off when they are sown broadcast; those which are sown individually are left undisturbed, which apart from the saving in time, is in fact one of the major advantages of this technique. Pricking off involves very careful extraction of individual seedlings or groups of seedlings (in the case of lobelia) using a dibber or tally and avoiding serious damage to roots. The advantages of early pricking off were emphasized by the John Innes Horticultural Institute many years ago.
Boxes are generally used for pricking out, using a compost nutritionally acceptable for the time of year. For most bedding plants allow about forty-eight or fifty per standard tray. The little seedlings must not be planted too deeply and they should be firmed gently with the base of the dibber. Recent years have seen a variety of propagating techniques being developed. Notable in this respect are the expanded polystyrene propagating system (a compartmentalized container with push out pegs) and the Arcol or similar trays.
Rather close, humid conditions are given for a few days after pricking off the plants then being given good light and plenty of air, subsequent treatment depending on method of culture dictated by species. A period of hardening off or acclimatization will be necessary for plants being moved to cooler quarters or out of doors, whereas permanently housedwill eventually be potted on, the same being true of plants being maintained in the greenhouse for stock supply purposes.
Propagation of ferns from
Spore sowing involves the use of very well-crocked pots and a very fine compost, the compost being watered by immersion before theare pressed into the surface and covered with glass. Place in a saucer or water to retain moisture. The little plants which appear, should be pricked off individually.
Always label seed boxes, pots and so on, with either plastic or wooden labels, giving dates, species and variety.