Propagation Of African Violet
There is no doubt that it is easy to propagate African violets, especially as there are several methods to increase successfully the number of plants from one. These methods are from a leaf, by a sucker or offset, by division and by seed.
Propagating from a leaf
All but one type of African violet propagate easily from leaves, although for greatest success the correct leaf must be selected. Thus the leaf must be mature and still have a good deal of potential growth in it; it is a mistake to take an old, nearly spent leaf from the outermost layer of leaves, because although it will produce plantlets it will take a long time to do so and they will not grow into such good mature plants. Nor should a young leaf from the centre of the crown be taken, as leaves do not achieve their full potential for propagation until they have grown to full size. Also its removal from the crown will spoil the shape of the plant. For rosette types, a leaf from the second or third layer of leaves from the outside would be the most appropriate. With trailing hybrids, a leaf from a similar layer on one of the branches should be removed for propagation.
The leaf is taken cleanly from the main stem of a rosette or the branch stem of a trailer by a sharp sideways tug so that no stub remains, as this could rot and infect the main stem. If a stub is left it should be removed as closely as possible to the stem. The leaf petiole should be trimmed to a length of 1.5in (4cm) and cleanly cut at a slanting angle using a sharp bladed knife or razor blade. The slanting cut is to expose a large area of tissue from which roots and plantlets will grow.
Sometimes one is given a leaf of a choice or rare hybrid, and its petiole is accidentally broken off at the base of the leaf blade. All is not lost, however, because a short stalk can be made by cutting away a small section of the leaf blade on either side of the main vein. This cut leaf may then be propagated following the normal method.
When propagating variegated hybrids, the leaf taken should have as much green color in it as possible. Even an all-green leaf from a variegate will produce variegated plantlets.
Propagating from a sucker or offset
Sometimes a rosette type of African violet will produce a tiny sucker or offset in a leaf axil instead of a flower stalk. If allowed to continue to grow in this position, suckers will cause a plant to become multi-crowned. However, if the sucker is carefully eased away from the leaf axil when it has six to eight leaves, it may be used to grow into another plant. Care must be taken that no damage, or very little, is done to its rounded base when removing it.
A small pot is filled with moist compost, and a small hole made in the centre surface; this is filled with damp vermiculite into which the sucker base is inserted. As the vermiculite is sterile and without any food value, roots grow quickly and spread into the surrounding compost. The sucker should then be kept in a humid, warm and light position out of direct sunlight, and grown on as a plantlet.
The quickest way to propagate a trailing African violet to get a good-looking plant is by cutting off a short branch -which is actually an elongated sucker -just above a leaf node and rooting it down in a pot of compost and vermiculite as for a sucker. Because the base of the cutting is a stem without leaves, it is much less likely to suffer problems in rooting. Taking this cutting is also useful to the original plant, as its stem will then branch again.
The usual way of propagating chimera African violets so as to keep the true flower pinwheel pattern is by sucker growth. Plants can be induced to produce suckers from leaf axils either by carefully removing just the centre growing point, or by beheading the plant. The latter method gives a new plant quickly by being rooted down, and later suckers to increase the number. It needs some courage for a fairly new grower to behead a plant, but it is very worthwhile if chimeras need to be propagated. A word of warning, however: extra care must be taken that the base of a chimera sucker is not damaged in any way. A nice rounded sucker base can be obtained if you remove the leaf below it early on, thus allowing the sucker to spread out; then when it is of good size, a gentle sideways tug will take it cleanly away from the main stem of the old plant. Don't be too greedy: don't allow more than two suckers to grow on an old plant at a time; they will then be much better quality for growing on. When they are removed, others will probably grow from other leaf axils, and the old plant will not be so stressed as to stop growing.
Propagating from seed
African violet seed is dust-fine and requires very careful handling before being sown.
A small shallow pan such as a margarine tub, with drainage holes made in the bottom and a layer of perlite in it about O.5in (1cm) deep, is filled with fine moist compost. It is stood in a dish of warm water until the compost surface is seen to be thoroughly wet, when it is removed and allowed to drain for at least two hours. The seed is sown very thinly onto the compost; it should not be covered with more compost nor with fine vermiculite. Like all gesneriads, African violet seed needs light to germinate. The pan should be covered with clear plastic film to create a humid atmosphere for the seed, and either kept in a warm, light position out of direct sunlight, or placed under fluorescent lights. Alternatively, the uncovered pan may be placed in a heated, covered propagator running at 70°F (21°C). When the first sign of germination is apparent in three weeks or less, the pan should be taken from the propagator, covered with clear plastic film and placed on a window-sill out of direct sunlight or under fluorescent lights.
Do not start worrying if germination takes longer than three weeks. The time it takes can depend upon how fresh the seed is, although it has been known for seed as old as four years to germinate in six to eight weeks. But sometimes apparently fresh seed does not germinate because it is not viable. Always leave a seed pan for several months before giving up on the seed and discarding it.
As the seedlings grow, great care must be taken that the compost does not dry out; watering involves standing the pan in a dish holding 0.5in (1 cm) of tepid water for ten to fifteen minutes to allow the perlite in the bottom of the pan to soak up the water. Once the seedlings have four tiny leaves they may be pricked out into quarter-size seed trays of moist compost, and covered with clear plastic film. The exception to this is with the all-white seedlings growing from seed of variegates: it is pointless to prick these out because they will not grow any more as they lack chlorophyll. However, all-green seedlings, or those with only a little green in their leaves, will grow on to be variegates and should be pricked out. When necessary water should be given from the bottom by standing the seedlings in a dish, and a quarter-strength high nitrogen fertilizer should be given at every other watering.
Once the seedlings are established and have grown so they touch the plastic film, this should be removed gradually to harden them off. As they grow on and their leaves begin to touch each other, the time has come to transplant them into individual small pots -these should be of a suitable size, in particular so they are not over-potted and do not have too much compost for their roots. Keep them in a warm, humid atmosphere for a few days so that they can recover from the transplanting. The seedlings should now be fed with an eighth-strength balanced fertilizer at every watering and grown on to maturity. Long before this the all-green seedlings of variegates will be showing their full variegation potential.
Micro-propagation, or tissue culture, is a method used by commercial nurseries to produce very many plants of a hybrid in a comparatively short period of time. It is carried out in laboratories equipped with special facilities for controlled sterile conditions. It is not a propagation method that the average hobby grower at home is normally able to use.
The process entails a small section of an African violet leaf being cleaned and sterilized with chemicals, and then placed on an agar gel in a jar with a screw-down lid. The agar contains hormones and nutrients to induce shoot production, and within a week or two the leaf section will be covered with a multitude of shoots; it is then removed from the jar, divided and replaced in more sterile jars containing the same formula agar. Division continues until the number of shoots, which at this time do not have roots, is considered adequate for the required plant production. At this point all the shoots are transferred to sterile jars containing agar of a different formulation, this having hormones and nutrients that will promote root growth, and the shoots begin to grow roots. Sometimes roots have been known not to connect with a shoot, thus making the shoot useless. After about two months the agar is covered with a mass of minute plantlets which may then be teased apart into individual ones, pricked out into compost, and grown on into young plants under nursery conditions.