Propagation Of Daylilies
Daylilies can be propagated vegetatively or by seed. Seeds should only be used to increase true species, grown in isolation, or for breeding programmes. Vegetative methods should always be used for increasing hybrid daylilies. Four vegetative methods are used: division, tissue culture, proliferations and the Lanolin-BAP-IAA method.
Division is the simplest and most reliable method, provided that the daylilies are not divided down to single fans, though this can be done successfully with practice. Dig the clump out of the ground then, resting it on the ground or on a hard surface, such as concrete, insert two garden forks, back to back, right in its middle. Slowly pull the handles of the forks together, making the tines act as levers thus separating the clump into two lesser clumps. The forks may then need to be forced outwards and downwards to completely separate the two new clumps. The process can be repeated, dividing lesser clumps into still smaller clumps, and so on. Final divisions should consist of not less than two fans. The last few fans can be separated by hand, following the natural separation lines as closely as possible, or cut apart using a sharp freezer or plant propagator's knife. The whole operation is generally made easier if the foliage is first cut down to 2-5cm (1-2in) above the crown.
After division, roots should be trimmed back to about half their length, again using a sharp knife. This will encourage the divisions to sprout strong new roots from just above the cuts rather than trying to reactivate old roots.
The divisions can then be either returned to the ground or potted up. If they are to be returned to the ground, they should not be replanted in the same place that they were growing in originally, unless the soil in the planting hole has been renewed or re-invigorated with organic manures and fertilizer. If the plants are to be potted this is best done into a proprietary growing mix. As a rule of thumb the pot should be large enough to contain at least twice the quantity of roots visible at potting time. Plants should be watered in thoroughly, shaded from strong sun and sheltered from severe winds until established -a matter of just a few weeks. They should also be clearly labeled.
Daylilies can be divided in the spring or the autumn, but one must be aware of local weather conditions and avoid dividing when it is too rainy, too hot or too cold. The optimum time, when there will be least disruption to the growth of the plant, is directly after the second burst of growth, that is immediately after bloom. That, however, is a counsel of perfection and many daylilies, being the tough and easy plants that they are, will accept division in most conditions other than intense heat or heavy frost, as long as the foliage and flower scapes are cut down so that the energy goes into building up a healthy new root system.
Proliferations are small fans of leaves occurring on the scapes, usually where there is a node or bract just below the point where the scape branches. On some daylilies these proliferations can develop into baby plants with leaves of 5-7cm (2-3in) and roots of about 1cm (1/2in). In theory, if the rooting part of the proliferation can be brought into contact with soil or a growing medium, the proliferation will develop into a fully fledged daylily genetically identical to the parent plant.
The practice is to sever the proliferation from the parent scape, making cuts about 2.5cm (1 in) above and below. The section of stem, with the proliferation still attached, is then pushed into soil or a potting mix, the tight way up, until the rooting part of the proliferation is firmly bedded in. Some people prefer to root them in vermiculite, perlite or sharp sand. After planting, the proliferations should be kept warm and in good light until established, which is usually a matter of weeks. If they have good roots while still on the scape, they may not need pampering, but if no roots are showing, new plants will develop more quickly and certainly if they are grown on under glass or in a propagator with bottom heat. Some growers recommend keeping the proliferations moist and warm by placing them under clear polythene but such close conditions may encourage rotting. The use of fungicides may avert this. Once they are established the young plants can be treated just like other daylilies.
Tissue culture is the process whereby whole plants are produced from single cells under laboratory conditions. It is a method that is really only suitable for nurserymen who want to reproduce particular daylilies in vast quantities.
At the present time, hundreds of thousands of daylilies are being produced by this method in many different countries, but with mixed success. A few, such as 'Joan Senior' and 'Gentle Shepherd', are known to come true to type, but many others do not. Most specialist daylily nurseries will know which do come true, and will not sell the unreliable varieties. If in doubt, make sure you see tissue-cultured daylilies in flower before buying.
It has been found that if the meristem or growing point of a daylily fan is damaged or removed, several fans will develop instead of just the one; although the more usual experience is that the whole fan dies. This can be done with Lanolin-BPA-IAA paste.
Advocates of this method claim that it is possible to get up to six new shoots in three to four weeks, and that with repeated applications one can get as many as 20 new shoots where originally there was only one fan. Others find that the method has no advantage over normal division and may even damage what would otherwise have been perfectly good fans. It is likely to be most successful in hot climates.
The seed of daylilies may occasionally germinate by chance in the garden, but when seedlings are being raised deliberately much more care needs to be taken. In general, seed is best sown under glass where the circumstances surrounding them can be carefully controlled. Failing that they can be sown in a propagating case or raised in a conservatory or even on a well-lit windowsill.
Broadly speaking, seed should be sown in early to midwinter, so long as the minimum temperature of 5°C (41°F) for germination can be maintained. Seedlings should be kept growing by potting them on as needed. In mid-spring they can be hardened off for planting out in late spring. If this regimen is followed plants should grow away strongly and most will flower in their second year.
Seed is normally sown in pots or seed trays, in a proprietary seed mix. The seed should be covered with its own depth of seed mix, or with silver or sharp sand. In close conditions a fungicide should be used against damping-off.