GrowingHQ
Seedlings

Seedlings collapsing at soil level

Young seedlings toppling over with a pinched, darkened, thread-thin stem where it meets the compost — healthy in the morning and flat by evening, usually in a patch that spreads across the tray.

What causes it, and how to tell them apart

Work down the list making the observation under each heading. GrowingHQ will not guess which one you have — the observation is the answer.

  1. Damping offvery common
    source

    Sourced guidancehigh confidence

    • Royal Horticultural Society: Damping off

    Checked 2026-08-13

    How to tell

    The stem is constricted and discoloured exactly at compost level and the seedling is still green. Spread across a tray in a patch rather than at random confirms it.

    source

    Sourced guidancehigh confidence

    • Penn State Extension — Pennsylvania State University: Damping off of seedlings

    Checked 2026-08-13

    If it is this, do first

    Remove the affected seedlings and the compost around them, increase ventilation and light, and stop watering until the surface dries.

    source

    Sourced guidancehigh confidence

    • Royal Horticultural Society: Damping off — prevention

    Checked 2026-08-13

  2. Slugs and snailscommon
    source

    Horticultural consensusmoderate confidence

    • Royal Horticultural Society: Slugs and snails

    Checked 2026-08-13

    How to tell

    The seedling has been chewed through rather than shrivelled — the cut is ragged, tissue is missing, and there is often no top left at all. Damping off leaves the whole seedling lying there intact.

    source

    Sourced guidancehigh confidence

    • Royal Horticultural Society: Slugs and snails — damage

    Checked 2026-08-13

    If it is this, do first

    Check for slime trails and look under the tray and around the staging.

    source

    Horticultural consensusmoderate confidence

    • Royal Horticultural Society: Slugs and snails

    Checked 2026-08-13

Commonly reported on