The act of confining a cactus in a small pot is a radical departure from its normal way of life, where roots spread widely and seek the shelter and moisture of rock crevices. Porous clay pots allow quick drying out and —if exposed to prolonged hot sun —scorching and death of the fine root tips. Plastic pots are less susceptible to this, but there is the opposite danger of waterlogging in damp, dull weather. Standing porous pots on a bed of shingle, or half plunging them, lessens the danger of baking, as does communal planting of small succulents in pans or troughs. In any glasshouse collection it is worth making at least one bed where the plants can be set out in open soil, if only to see a select few of the largergrowing speciesat their best (1.4). Tall cerei. for instance, flower much more profusely when bedded than when kept in pots. But management of beds is more difficult, because some specimens easily become too large and smother the remainder. It is also important to leave gaps for access for removal of weeds and general clearing up.
For indoor culture, plants are commonly displayed in troughs or bowls, which can range from the plain and functional to the elaborately ornate, often costing more than the plants they contain (6.15). If the display is to be permanent, the container must be deep enough for a good layer of soil. 6-8cm (2!4-3in), plus drainage crocks, which are doubly important if there is no outlet for water.
Right (6.15): Decorative containers add much 1 to the presentation ot exhibition specimens In this case Sarcocaulon burmannii is well displayed in an attractive ceramic pot. Below (6.16): A veteran plant ot Haworthia batesiana has been unpolled, inverted, bound with plastic cord and suspended like a basket I a novel mode ot presentation.
Raising plants from seed Those who buy only adult specimens for their collection miss half the fun of life with succulents. They can never know the deep satisfaction that comes from seeing the first flower on a plant of their own raising from seed. Seedlings are often unlike the adult plant and have a special charm of their own: like kittens, some are never so delightful when they grow up. Elaborate equipment is not needed for raising seedlings. Many first attempts begin on a sunny windowsill in summer, and a domestic airing cupboard over a hot-water tank can be pressed into service for germination, although light is needed when green sprouts appear.
Germination of succulents is not basic ally different from that of mesophytes. It requires moisture and warmth, and the seedlings will need gradual acclimatization to the cruel world outside. In nature, only those seedlings that come up in the rainy season in the shade of rocks or other plants are likely to survive. Depending on the size of the seed, its stores of food are exhausted more or less rapidly, so if you sow on an inert medium such as sand, growth will be checked unless the seedlings are fed or pricked out on to a more nutritious compost.
For germination a minimum temperature of 15°C (59°F) is needed; up to 25°C (79°F) will do no harm. There are many ready-made propagators on the market, but a handyman can make his own (6.18). Some are quite elaborate, with separate heater cables above and below soil level, and these can be used for raising both seed and cuttings.
Spring is the ideal time for sowing seed (6.17), and the seedlings are best kept warm and watered throughout their first winter. John Innes Seed Compost or a peat sand mixture can be used after passing through a sieve to separate the coarse particles, which are used as drainage with the fine residue on top. Tiny seeds should not be covered; with larger ones the old rule applies, that you cover them for their own depth. Sifted grit is a good top dressing, because the particles, give support and leverage to the emerging seedlings. It is a common mistake to sow seed too thickly: pricking out the forest of tiny plantlets is then difficult. It is better to sow thinly so that they can be left to develop their first shoots before the need to transplant. Provided they do not starve, the fact that they come to touch one another will not matter.
To maintain an even, humid atmosphere in a seed pan, it is usual to cover it
Below left (6.18): Seed raising over a radiator The seed pan is enveloped in a polythene bag. and watering is automatic by a wick siphon recharged from an upturned bottle.
Below (6.19J: Fortnight-old seedlings of Conicosia with two lleshy cotyledons and the seed coat borne at their tips. The first foliage leaf is seen on the right.
with glass or polythene and, if exposed to direct sunlight, with paper or some other material that will diffuse the light. Gradually the glass is raised and the shading removed as growth proceeds. Some growers put their pots of seed inside sealed polythene bags and leave them for several weeks, until the plants are large enough for pricking out. As long as the pot is clean and the soil sterile, all should be well. If seedlings elongate and go pale and leggy, it is a sign that they are getting too little light and air.
Some seeds—those of Stapelieae, for instance—germinate in from two to four days under favourable conditions; any not up within a fortnight can be counted as lost. Others take longer, or appear erratically: Othonna for example. A few germinate better the second season than the first. With these one must be patient and not discard the seed pan too soon. Instead, leave it to dry right out in the sun, stir up the topsoil, water it, and return it to the propagator. Erratic germination is an advantage in nature: if all seedlings came up at once, a severe drought or other natural disaster would kill every one and leave nothing in reserve. Thus we find many mechanisms, both mechanical and chemical, that retard germination. Opuntia seeds, for example, have a thick, waterproof coat and usually germinate only after exposure to a cold winter. Some growers recommend refrigerating them before sowing.
Failures are sometimes due to the seed being old or non-viable. If in doubt, and if the seed is not too tiny, cut one open: this can be done conveniently with a pair of blade-and-anvi! secateurs. The contents should be plump and white. If they are shrunken or discoloured, the answer is obvious. Another test for seed is to stir it up in water. Good seeds usually sink; any that float should be rejected. Freshly harvested seeds from your own plants usually germinate better than packaged seeds, especially if these are old.
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