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Etiolation

Also known as Leggy growth, Stretching, Low light

DiseaseHarmful
Etiolated ivy grown in the dark next to a normal stem Photo: Rosser1954 · CC BY-SA 4.0

In short

Etiolation is the stretched, pale growth a plant makes when it does not get enough light. The plant spends its energy lengthening stems to reach light, so internodes become long, stems weak and leaves small and pale. More light fixes new growth, but stretched stems stay stretched.

How it looks

Stems grow long and thin with wide gaps (long internodes) between leaves; leaf stalks become unusually long. New leaves are smaller and paler, yellowish-green or, in complete darkness, nearly white because little chlorophyll forms. Plants lean or grow toward the window. Rosette plants and succulents lose their compact shape and stretch upward. Variegated plants may lose variegation, lower leaves yellow and drop, and flowering is poor or absent.

Signs

Leggy, floppy stems; wide spacing between leaves; pale new growth; leaning toward the light; loss of variegation; lower leaf drop; few or no flowers.

What favours it

Positions too far from windows, north-facing or shaded rooms, short dark seasons, seedlings started indoors without enough light, and plants kept under covers. Warm temperatures with low light make stretching worse.

Prevention

  • Place plants according to their light needs; move them closer to a bright window.
  • Use a horticultural grow light for seedlings and light-hungry plants; give plants a daily dark period and no more than about 16 hours of light.
  • Rotate pots regularly so growth stays even.
  • Reduce feeding in darker seasons when growth slows.

Treatment

Start with the first step and move down only if the problem persists.

  1. Increase light gradually, acclimatising the plant so it does not scorch.
  2. Stretched stems will not shorten; prune leggy stems back to encourage bushier new growth once light is improved.
  3. Use healthy stem tips as cuttings to restart compact plants, or re-root the tops of stretched succulents.

Pros and cons

Cons

  • Weak stems break or flop and need support.
  • Stretched growth is permanent and spoils the plant's shape.

Look-alikes

Nutrient deficiency
Deficiency causes pale or yellow leaves but not long, stretched stems.
Overwatering
Waterlogging yellows lower leaves without stretching; check whether the mix stays wet.
Natural climbing or trailing habit
Vines naturally have long stems but keep normal-sized, well-coloured leaves.

Affected plants

Any plant in insufficient light; very obvious in succulents and cacti, seedlings, herbs, trailing plants such as ivy and pothos, and flowering plants.

Sources

  1. Etiolation — Wikipedia
  2. Houseplant Problems — UC Statewide IPM Program
  3. How to help a poorly houseplant — RHS
  4. Diagnose Indoor Plant Problems — University of Maryland Extension
  5. Excess Light on Indoor Plants — University of Maryland Extension

Written in our own words from these sources. Check a product label before using any treatment.