Bulbs, corms & tubers – the same but different

October sees the start of the main bulb planting season with daffodils, crocus, tulips and many more appearing in garden centres and nurseries.   But there is more to bulbs than the common spring flowering selections and understanding a bit about their lifecycle can help you to be more confident and more adventurous in your choices.


In fact bulbs, corms and tubers are all slightly different but are all used by the plant to store energy captured one year for use the following year.  The food, stored as starch, is used to fuel early growth and the plant then replenishes its store later in year when growing conditions are good for use the following spring.  Daffodils are a good example of this cycle: we plant fat bulbs in the autumn and it is the food stored in the bulb that fuelsflowering in March, before the leaves are making much food through photosynthesis.  Once flowering is finished the plant captures energy from the sun through its leaves and stores it in the bulb ready for next year.  If the leaves are cut off too soon the bulb will remain small and shrivelled and you will get poor flowers the following year so it is important to retain the leaves, not tied up or cut off, for at least 6 weeks after flowering.

Bulbs are made from thickened leaves at the base of the stem with the new shoot growing from the centre – daffodils and onions are typical bulbs.  Corms, e.g. crocuses, form when the stem itself thickens to store food and they are solid if you cut them open.  Tubers come in two types: Stem tubers, e.g. potatoes, form at the end of underground stems and as well as storing food they produce new shoots from buds on their surface. Root tubers, e.g. Dahlias, form when food is stored in the roots and therefore do not produce new shoots.  Bulbs and root tubers use their stored food and then re-fill the same bulb or tuber for many years.  Corms and stem tubers are not re-used by the plant, once they are empty they shrivel and food is stored in new corms or tubers.

Of course, there are plenty of summer flowering bulbs too including the ever popular Lilies. These are great for growing in deep pots ready to be nestled in beds and borders amongst the foliage of herbaceous plants whose moment of glory has passed or is yet to come, or to fill unexpected gaps where a plant has failed.  Cheating?  Absolutely right!

Whichever bulbs, corms or tubers you choose to plant this autumn, understanding how they grow will help you to enjoy beautiful spring and summer flowers for years to come.

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