This feature looks at the cultivation of hardy and tender bulbous plants from seeds. For practical purposes, gardeners frequently treat the true bulbs such as daffodils and lilies, and plants that produce corms including gladioli and crocuses, as "bulbs". By adopting these straightforward techniques, all of them can be grown successfully from seed to produce a host of glorious flowering plants.
Why Grow Bulbs From Seed?
Bulbs are eternally popular plants for the garden and greenhouse, and many can be obtained very cheaply from garden centers and supermarkets. This being the case, why grow bulbs from seed? Some species take many years to flower from seed or have the reputation of being difficult. While this is sometimes true, other species including Freesia and Habranthus (rain lilies) can flower within 9 to 18 months from sowing.
Seed may be the only way to obtain some of the most unusual species. A good example is the gorgeous Lachenalia viridiflora, renowned among bulb enthusiasts for its unique coloration. This South African bulb was discovered as recently as the mid 1960s and is known from just one location where it is critically endangered. Fortunately, it is easily grown from seed, a virtue that may ensure its long-term survival.
Bulb Seeds
Bulb seeds are as diverse as the plants that produce them, and need to be treated in different ways. Many amaryllids, including Hippeastrum and Habranthus, produce flat lightweight seeds with a papery texture. Lilies, fritillaries, Gladiolus and Watsonia are also usually papery or flattened in shape. Other amaryllids have large fleshy seeds with a short viability: this group includes the clivias, crinums and the South American genus Hymenocallis. The freesias and chasmanthes have hard round seeds, while those of Lachenalia, the Cape cowslips, are often tiny or dust-like.
Sowing Hardy Bulbs
Theoretically, the seeds of many hardy bulbs can be sown directly in the open ground. Anybody who is familiar with the grape hyacinths (Muscari), will know how rapidly the more prolific species can spread in the garden. Success rates are greatly enhanced, however, if hardy bulb seeds are sown in pots and given the protection of a cold frame or cold greenhouse.
Using a good, gritty seed compost, hardy Lilium, Narcissus and a host of other bulbs can be sown thinly in deep pots, preferably in Autumn or early Spring. Thin sowing is important to prevent overcrowding and disease, and deep pots are advisable for bulbs as many have deep root systems and contractile roots that pull the developing bulbs or corms down to a surprising depth. Cover larger seeds to no more than twice their depth with sieved compost and a thin layer of horticultural grit to impede the growth of mosses. Small seed can be covered with a fine layer of compost or silver sand. In either case, place the pots in a semi-shaded place, ensuring that they do not dry out or become waterlogged.
Sowing Tender Bulbs
The techniques for sowing many of the half-hardy or tender bulbs are identical to those mentioned above, but depending on the species, some degree of warmth needs to be supplied. In the case of freesias and rain lilies (Zephyranthes and Habranthus), average room temperature is usually sufficient. A little extra warmth to 18º C can hasten germination, but care should be taken that the seedlings do not grow too quickly and become soft and etiolated. The fine seeds of lachenalias can be sown on the surface of the compost and covered with a sprinkling of silver sand to anchor the seeds.
Another way to germinate large, papery seeds is to float them on the surface of a glass of water and stand this in a warm room. As the seeds germinate the emerging roots can be clearly seen, and each seed can be carefully removed with tweezers and planted up.
Large, fleshy seeds need to be treated differently. These should be sown into individual pots and pushed into the compost to half their depth. A word of warning, however: when buying these large seeds from mail order companies they are frequently already germinating and should be unpacked carefully to avoid damaging the roots.
Germination of Bulb Seeds
All bulbs and corms are monocots, plants that have only one seed leaf. The exact process of germination varies between species but the first leaf to emerge above ground is usually flat, cylindrical or similar to a blade of grass, and must not be mistaken for such.
Aftercare of Bulb Seedlings
It is perfectly acceptable to leave less vigorous bulb seedlings and evergreen species in their pots for several years if they have sufficient space. Seasonally dormant bulbs and corms usually lose their leaves after 6 to 9 months of growth, which is a good time to check them for disease before potting the healthy young bulbs into larger containers.
The sight of some bulbs flowering in as little as 9 months will hopefully inspire you to try a few of the more unusual types. Although some may take many years to reach flowering size, the sense of pride and achievement when this finally takes place is a truly worthwhile experience!
References
Plantzafrica.com Lachenalia viridiflora www.plantzafrica.com
Peter Ashby - Peter Ashby lives near Granada in southern Spain, is an expert on natural history, and a dedicated traveller, writer and hispanist.
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