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Underwatering

When roots cannot find water fast enough, leaves droop, then crisp at the edges and drop. Fruiting plants shed flowers and small fruit. Container plants in summer can go from fine to flat in a single hot afternoon.

Water & drainage
A drooping plant in dry, cracked soil
A drooping plant in dry, cracked soil

What it looks like

Thirst shows first on the softest growth and on the sunny side of the plant.

  • Leaves hang limp and recover in the evening. Lasting wilt means the plant is truly short.
    Midday flop Leaves hang limp and recover in the evening. Lasting wilt means the plant is truly short.
  • Leaf edges and tips dry to brown and papery, starting with the oldest leaves.
    Crisp margins Leaf edges and tips dry to brown and papery, starting with the oldest leaves.
  • Dry compost pulls away from the pot wall, so water runs straight past the roots.
    Shrunken compost Dry compost pulls away from the pot wall, so water runs straight past the roots.
  • Peppers, beans and tomatoes shed blossom and young fruit after a dry spell.
    Dropped flowers and fruit Peppers, beans and tomatoes shed blossom and young fruit after a dry spell.

How to confirm it

The soil makes this the easiest diagnosis to confirm.

  1. Check the depth

    Dig or push a finger 5 cm (2 in) down. Dry there means the roots are dry too.

  2. Watch the recovery

    Water thoroughly. A thirsty plant perks up within hours; one with root damage does not.

  3. Note the timing

    Wilting on hot afternoons that clears by evening is heat as much as water. See heat stress.

What to do

Rewet slowly and deeply, then change the rhythm.

  1. Soak dry pots

    Stand dried-out containers in a bucket of water for 30 minutes until bubbles stop, then drain.

  2. Water deeply in the ground

    Give beds a long soak rather than a daily sprinkle, so the water reaches the whole root run.

  3. Mulch

    Cover the soil with 5 cm (2 in) of compost, bark or straw to slow evaporation.

  4. Pick off crisp leaves

    Damaged leaves do not recover. Judge the fix by the new growth.

Prevent it next time

  • Check pots daily in hot weather; hanging baskets may need water twice.
  • Move plants up to larger containers, which hold more water.
  • Group pots together and out of the wind.
  • Water in the morning or evening, at the base rather than over the leaves.

What not to do

Do not feed a drought-stressed plant until it has been watered and recovered; fertiliser in dry soil scorches roots.

In the growing guides

Where the guides mention it, with plant-specific advice.

Sources

  1. Weather damage, Royal Horticultural Society
  2. How plants absorb water, Royal Horticultural Society