Is the soil acid, alkaline, or neutral? If lilies are to flourish, it is important to know the correct answer. It can easily be discovered and measured with the aid of simple and freely available chemicals. Measurements are expressed in terms of pH value: pH 7 is neutral, but lilies prefer slightly acid soils around pH 5.5—6.5. More acid soils, to pH 4, are tolerated by the Japanese lilies, including L. mtratum, L. speciosum, etc., the American bog lilies and also L. canadense, while soils of pH values between 6 and 7 are preferred by L. martagon and L. candidum. Excess acidity of soils is easily corrected by applications of basic slag, lime, or quicklime. Conversely, if acidity is to be increased, liberal dressings of-mould or peat are helpful, as is superphosphate. Certain lilies, like and some Asiatic gentians, require lime-free soils and prefer soft water to hard water containing lime. The Japanese and North American lilies already mentioned also have these preferences.
Dung, when fresh, isto lilies; it must not be used until at least two years old and then only spread thinly, during autumn or spring, over the topsoil. Dung must never be dug in, nor, if fusarium is to be avoided, must be permitted to come into direct contact with lily bulbs.
Balanced artificial fertilizers are very suitable, particularly the types sold for potatoes, which contain little nitrogen but have a high potash content. The first application is made during early spring, so that rain or melting snow can carry it down into the soil; the second when the first signs of growth appear. If liquid applications are preferred, the fertilizer is easily dissolved in water for a 0-3 per cent solution, about 1 ounce (a fistful) is needed to 2-} gallons of water (2-½ us gallons). Frequentwith this solution during spells of drought is not only safe but most beneficial, provided that fertilizers are not applied after the flowering period – lilies only absorb potash at this time and no nitrogen; too much nitrogen encourages fusarium. The amount of powder or liquid fertilizer applied is dictated by the level of fertility of the soil, and should not exceed 1 ounce per square foot per year.
As with all bulbous plants, a liberal supply of potash is most important. This is also confirmed in nature, where observations in North America have clearly shown that lilies, during years following a forest fire, always grow more vigorously and produce a greater number ofthan during normal years – undoubtedly as a result of the extra potash obtained from the burnt timber. According to a South African lily-breeder, additional potash reduces botrytis. Feeding lilies is not complicated ; the main essential is to avoid overfeeding.
Mulching improves the soil by applications of grass, peat, or other partly rotted vegetative matter usually applied during the growing period. Ferns, rich in potash, are useful, as are sawdust and wood shavings, which are much used in North America. Chopped or whole straw not only makes a cover against frost, but also good mulch – but it should not be used if there are mice about; they like to nest in it, and live on the lily bulbs. The nitrogen absorbed during the rotting process of the sawdust and wood shavings must be made good by an early spring dressing. Mulch insulates the hot rays of the sun from the soil and therefore keeps lily cool; but, conversely, mulching during periods of late frost is disadvantageous, and keeps the ground colder than it would normally be.
Fungus diseases must not be ignored; they are apt to attack lily bulbs, which must be protected with a fungicide. Voles, if present, can be kept out by wire netting; wircworms, caterpillars and cockchafers by one or another of the very effective proprietary chemicals (such as benzene hexachloride) on the market. For safety’s sake, manufacturers’ detailed instructions should always be followed exactly, and chemicals should not be used near vegetable patches.