The difference between bulbs, corms, tubers and rhizomes

Dazzling flower bulbs

A true flower bulb is similar to an onion: a flower bud surrounded by scales that contain nutrients. Its green shoots emerge from the top of the flower bulb while its roots grow from underneath. The lily is a very popular flower bulb. Unlike most summer-flowering bulbs, this one will survive through the winters and will easily produce beautiful flowers year after year. Other favorite summer-flowering bulbs include the Star-of-Bethlehem (Ornithogalum), Gladiolus and Pineapple Lily (Eucomis).

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Top 10 most popular corms, tubers and rhizomes

Corms, tubers and rhizomes are often referred to as bulbs but they are actually slightly different. Corms, tubers and rhizomes are not made up of individual scales (as true bulbs are) but are a solid material. Their food reserves are stored in their fleshy roots (corms, tubers and root rhizomes) or stems (stem rhizomes). Located on the surface of these underground storage organs are axillary buds (eyes) from which the roots and shoots emerge. One of the most widely sold tubers is the Dahlia. This gorgeous eye-catcher adds loads of color from the second half of the summer to the first frost. And you can have them in every color of the rainbow. The tuberous begonia is another tuber with a very long flowering period. There are a vast number of corms and tubers that produce beautiful flowers. Here are 10 of the most popular ones.

  1. Lily (Lilium)
  2. Begonia
  3. African Lily (Agapanthus)
  4. Gladiolus/Sword Lily (Gladiolus)
  5. Good Luck Shamrock (Oxalis)
  6. Calla Lily (Zantedeschia)
  7. Ranunculus
  8. Canna Lily (Canna)
  9. Cyclamen
  10. Anemone (Anemone coronaria ‘De Caen’)


Special rhizomes

Rhizomes look quite unlike bulbs, corms and tubers. These are underground stems that usually run horizontally below the surface. The ends of rhizomes often bend upwards to produce a new plant.
Here a some beautiful examples:

  • Bearded Iris (Iris germanica)
  • Japanese Iris (Iris ensata)
  • Peruvian Lily (Alstroemeria)
  • Ginger Lily (Hedychium)
  • Solomon’s Seal (Polygonatum)
  • Peony (Paeonia)

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Practical gardening tips

  • Summer-flowering bulbs, corms, tubers and rhizomes can be planted in the spring (April or May) after the last frost.
  • If you choose varieties with different flowering periods and heights, you can have a colorful garden from June to the end of October. They require watering only during dry periods. If they start to wilt, simply give them a splash of water and they will automatically perk up again!
  • If you forgot to buy a bunch of flowers for indoors, remember that most of these summer-flowering ‘bulbs’ will make wonderful cut flowers – just pick them from your garden!