Repotting guide

When & how to repot Iceberg Lettuce (Lactuca sativa var. capitata 'Iceberg')

Also called iceberg lettuce, crisphead lettuce.

More about iceberg lettuce

About Iceberg Lettuce

Lactuca sativa var. capitata 'Iceberg' · also called iceberg lettuce, crisphead lettuce · edible

Iceberg is a crisphead lettuce forming a large, dense, round head of pale, very crunchy, mild leaves. It is the most demanding lettuce type, needing steady cool conditions, even moisture and space, and matures in about 70-85 days. Reliable cool-season cropping makes it popular, though it bolts readily in heat.

Mature size: 25-30 cm across and 15-25 cm tall at heading.

How to tell iceberg lettuce needs repotting

Repotting on a calendar is less reliable than reading the plant. For iceberg lettuce, watch for these signs:

Roots circling the bottom of the module or pot, or poking out of the drainage holes.
The seedling dries out within a day and growth has visibly stalled.
Roots are white and matted in a tight spiral when you tip the plant out.
It has outgrown its current container for the stage of the season — pot iceberg lettuce on before it becomes hard root-bound.

For the underlying biology of a pot-bound root system and why it stalls a plant, see our guide to spotting and fixing a root-bound plant.

How often to repot iceberg lettuce

Pot on seedlings as they grow; not a perennial repot. Iceberg Lettuceis grown for one season, so the question is really “how often to pot on” — keep moving it up before the roots circle. Crisphead annual forming a single large, tight, rounded head; bolts into a tall central flower stalk when heat- or moisture-stressed..

What size pot to step iceberg lettuce up to

Pot iceberg lettuce on gradually — a seedling jumped straight into a huge pot sits in cold, wet, airless soil and stalls. Step up one or two sizes at a time as the roots fill each container, finishing in a large final pot or the ground. The aim is roots that never circle and never check.

Not sure of the exact diameter? Our pot size calculator takes the current pot and root spread and tells you the right next size — it deliberately recommends a single step up, never a big jump.

The best time of year to repot iceberg lettuce

Pot iceberg lettuce on through the active growing season, whenever roots fill the current container — there is no single date, just "before it becomes root-bound". Avoid potting on during a cold snap.

Step-by-step: repotting iceberg lettuce

Pot on before it is root-bound. Check iceberg lettuce regularly; move it up as soon as roots reach the edge of the cell or pot, not after they have circled.
Step up one or two sizes. Choose the next container up — not a giant one. Cold, wet, unused soil around a small root system stalls seedlings.
Knock it out gently. Support the stem, tip the pot, and ease the rootball out without breaking it. A little teasing of circled roots at the base is fine.
Pot into rich mix. Set it into fresh fertile, moisture-retentive, free-draining soil at the same depth (tomatoes are the exception — they can go deeper to root along the stem).
Water in and grow on. Water well, keep it in good light, and resume feeding once it is established and growing again.

Aftercare

Water iceberg lettuce in well and keep it in bright light; a freshly potted-on seedling can wilt for a day while roots settle, so do not overcompensate by drowning it. Do not fertilise for about 1 week — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for iceberg lettuce

Iceberg Lettuce wants fertile, moisture-retentive, free-draining soil. Prefers deep, well-worked soil high in organic matter at pH 6.0-7.0. Needs more space than leaf types, spaced about 30 cm apart; firm, fertile ground supports solid head formation. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting iceberg lettuce — frequently asked questions

How often should you repot iceberg lettuce?

Pot on seedlings as they grow; not a perennial repot for iceberg lettuce. Iceberg Lettuce is a seasonal crop, so you pot it on as a growing plant rather than repotting a perennial. Step seedlings up gradually into fertile, moisture-retentive, free-draining soil so the roots never circle the cell, ending in a large final container. A root-bound transplant stalls and never fully recovers.

What size pot does iceberg lettuce need?

When is the best time of year to repot iceberg lettuce?

Can you put iceberg lettuce straight into a much bigger pot?

No. Even a fast-growing iceberg lettuce should only go up one pot size at a time. A vastly oversized pot holds a reservoir of wet soil the roots cannot reach, which stays cold and soggy and rots the roots — the opposite of what you wanted.

Should you fertilise iceberg lettuce after repotting?

Not immediately. Wait about 1 week after repotting iceberg lettuce. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.