Too little light
Plants short of light grow long and thin between the leaves as they reach for it, lose colour, and stop flowering. Seedlings on a windowsill and houseplants far from the glass show it first.
Light & temperature
What it looks like
Growth reaches and stretches, and the gap between leaves widens.
-
Leaning stems Everything bends towards the window. -
Long gaps between leaves Stems stretch and leaves sit far apart. -
Pale new leaves New growth is small and lighter green than the old. -
No flowers Flowering plants stay leafy and never bud.
How to confirm it
Compare the plant with where it stands.
-
Measure the distance
More than a metre (3 ft) from a window, most plants are in low light.
-
Turn the pot
If it leans back towards the glass within days, it is reaching for light.
-
Check the season
Stretching that starts in autumn and eases in spring is the day length.
What to do
Give more light, then let new growth replace the old.
-
Move it closer
Put plants beside a bright window, or seedlings right against the glass.
-
Add a grow light
An LED grow light 10 to 20 cm (4 to 8 in) above seedlings for 14 to 16 hours a day stops stretching.
-
Pinch or cut back
Pinch leggy herbs and cut back stretched houseplant stems so they branch from lower down.
-
Resow if needed
Badly stretched seedlings rarely make strong plants; a fresh sowing under better light often catches up.
Prevent it next time
- Sow indoors later rather than earlier, when days are longer.
- Rotate windowsill pots a quarter turn every few days.
- Choose low-light houseplants for dim rooms.
- Thin crowded seedlings so they do not shade each other.
What not to do
Do not feed a stretched plant to 'build it up'. More nitrogen makes softer, leggier growth.
In the growing guides
Where the guides mention it, with plant-specific advice.
Sources
- Leaf damage on houseplants, Royal Horticultural Society