What have I got?
Pick the shape that looks most like what you are holding. Cut one open if you can: the inside tells you most.
A bulb
A short stem (the basal plate) wrapped in fleshy scales that hold the food store, with the next flower folded inside.
Check: Cut it in half: you see layers like an onion.
What to do: Plant pointed end up at two to three times its height. To make more, take offsets or (for lilies) scales when dormant.
Plants that grow from bulbs
- Allium (ornamental onion)
- Camas
- Crown imperial
- Daffodil
- Dog's-tooth violet
- Dutch iris
- English bluebell
- Garlic
- Glory of the snow
- Grape hyacinth
- Hippeastrum (amaryllis)
- Hyacinth
- Iris reticulata
- Lily
- Nerine
- Onion (sets)
- Pineapple lily
- Rain lily
- Shallot
- Snake's head fritillary
- Snowdrop
- Squill
- Star of Bethlehem
- Summer hyacinth
- Summer snowflake
- Tiger flower
- Tulip
A corm
A swollen, solid stem base. No layers inside, just starchy tissue, with a papery tunic and buds on top.
Check: Cut it in half: it is solid all the way through.
What to do: Plant pointed side up. Each year a new corm replaces the old one; save the cormlets and grow them on.
Plants that grow from corms
A tuber
A swollen piece of underground stem that carries buds (eyes) scattered over its surface.
Check: Knobbly, with eyes or dimples; solid when cut.
What to do: Plant with eyes facing up (begonia: hollow side up). Cut only with an eye on every piece, and let the cuts dry.
Plants that grow from tubers
A rhizome
A stem that grows sideways at or just below the soil, with nodes that make shoots above and roots below.
Check: Grows horizontally and is segmented, with a shoot at the growing tip.
What to do: Plant horizontally, shallow, with the growing tip pointing the way you want it to go. Divide by cutting at nodes.
Plants that grow from rhizomes
A tuberous root
A true root swollen with food. It has no buds of its own: new shoots come only from the crown where the roots join the old stem.
Check: A cluster of fat fingers joined at a crown; a finger with no crown piece will not sprout.
What to do: Keep every piece attached to part of the crown. Plant with the crown buds at the right depth for the plant.
Plants that grow from tuberous roots
Not sure? Garlic cloves, onions and tulips are bulbs; crocuses and gladioli are corms; potatoes and begonias are tubers; irises, cannas and ginger are rhizomes; dahlias and peonies have tuberous roots. Read the full explainer.