Bulbous Plants – Flowering Bulbs, Corms and Tubers

bulbs, corms and tubers I am often asked to define the terms bulb, corm and tuber for they are rather confusing to many gardeners, especially as all three are often described collectively as ‘bulbous plants’. I am a gardener, not a botanist, but I will do my best to make myself understood.

  • A flowering bulb is, in effect, a modified bud, usually found underground, with tightly packed scales or swollen leaf bases forming a food storage organ. It also contains the undeveloped shoot from which will arise next season’s leaves and flowers.
  • A corm, on the other hand, is what is termed a ‘solid bulb’ – a bulb-like fleshy stem, usually covered by a membraneous sheath, with the food storage. Organ developing a bud at its apex.
  • A tuber consists either of a swollen stem or a swollen root, the first bearing buds or ‘eyes’ and the second making growth from a crown.

Flowering bulbs are the most accommodating and diverse of plants, and there is hardly anywhere in a garden that is not suitable for one sort or another. Even in shade under a north wall or under trees, winter aconites, bluebells and snowdrops thrive.

And although usually thought of principally as flowering in spring, there is seldom a month when bulbs are not in bloom.

A true flowering bulb is made up of thickened leaves, hopefully with an embryo flower bud inside. Corms, such as crocuses and gladioli, consist of modified stems. Tubers are composed of thickened underground roots, anemones and winter aconites being examples.

Almost all plants grown from flowering bulbs, corms and tubers have a resting period when their foliage dies down. Some prefer to be dug up, dried off and stored in net bags or old stockings, in a cool, frost-free, dry and airy place until replanting shortly before growth recommences. This technique suits hyacinths and tulips, other than the small species, and most summer-flowering bulbs that die down in autumn.

Tulips, ideal for spring bedding, can be planted in masses by themselves, or among wallflowers, forget-me-nots, double daisies or polyanthus. As hyacinth bulbs are expensive and their flower heads are easily knocked down by rain, they are more popular in tubs and window boxes

After flowering, tulips and hyacinths can be moved to make room for summer bedding plants. The bulbs should be dug up with their leaves intact and replanted into shallow trenches until their top growth dies down and they can be stored.

Bulbs that remain in the ground for several years save work, but their foliage must not be cut off until it turns yellow, generally in late May with crocuses, for example, and early July with daffodils. Siting groups close to edges of lawns, around trees, or on hedge banks, allows most of the grass to be mown. Bulbs particularly suitable for naturalizing in this way include daffodils, chionodoxa, winter aconites and Fritillaria meleagris. Bulbs can be planted with a trowel or bulb-planter, which acts rather like an apple corer. If being planted in grass, an H-shaped cut can be made in the turf, slicing under it with a spade and rolling it back in opposite directions from the centre. The bulbs are then planted and the turf replaced. Planting depths in the tables are the depth above the top of the bulb.

Fertilizers should be applied only in moderation. Flowering bulbs will grow in almost any soil, but to keep them flowering, naturalized bulbs need a scattering of bonemeal every winter. Those not set in grass should have a mulch of peat or leafmould.

29. September 2010 by Dave Pinkney
Categories: Bulbous Plants, Plants & Trees | Tags: , | Comments Off on Bulbous Plants – Flowering Bulbs, Corms and Tubers


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