Home Gardening techniques How to fix leggy seedlings

How to fix leggy seedlings

Seriously leggy tomatillos... will they survive?
Seriously leggy tomatillos... will they survive?

Or prevent it from happening in the first place

It’s a disaster – your carefully nurtured seedlings have turned into drawn, thin, spindly beings, all pale stem and hardly any leaves.

They’ve gone leggy but can they be rescued? Well, yes and no.

It happens to the most experienced of gardeners, especially if you’re trying something new. Pictured here are my tomatillo seedlings which quickly flopped but were rescued too.

These are the main causes of weak, elongated stems:

Too much heat

The top three here almost always linked and happen usually to eager beavers who can’t wait to get started. Maybe you’ve just bought a heated propagator.

One thing I fell foul of was growing super hot chillies which needed to be started early at a high temperature. They were fine but the tomatillos I sowed in the same propagator became leggy.

It’s because they put on an unnatural growth spurt, stretching up to reach the light.

Prevention: Always sow at the temperature recommended on the packet – too hot can be as damaging as too cold.

Tomatillos repotted with the stems well buried
Tomatillos repotted with the stems well buried

Too little light

The most common cause if you sow too early. They are literally struggling upwards to get as much light as possible, then the stems become so weak they can’t support the leaves.

Prevention: Sow later or invest in a grow lamp. Seedlings will naturally lean towards the light, especially on a windowsill, so turn every day.

Use some aluminium foil or white reflective material behind seed trays to maximise light levels.

Sowing too early

Without a grow light or propagator, you’re likely to fall victim to the above.

Prevention: Wait a month to make use of lengthening natural daylight. The seeds will grow stronger and more quickly.

Poor seed sowing compost

Cheap or old compost saves you nothing in the end. Without the correct nutrition, seedlings become leggy even if light levels, etc, are good.

Prevention: Buy good-quality compost – worth its weight in gold.

Lack of moisture

If you forget to water, seedlings wilt quickly. This means they can’t access the nutrients they need, so end up starving.

Prevention: Check every day and don’t let them get dry.

Recovering tomatillos with new leaf growth, February 25
Recovering tomatillos with new leaf growth, February 25

Still air

Seedlings grown outside are naturally buffeted by the wind – this leads to strong, sturdy stems – in effect, resistance training! Seedlings grown inside are in a becalmed environment, so are weaker.

Prevention: Gently run your hands over the tops of the seedlings daily to strengthen stems.

How to cure weak seedlings

My tomatillos recovered well after being potted on into a decent compost – bury the stems deep, as roots will form under the soil – tomatoes respond especially well to this.

Keep them in good light, not too warm and brush your hand gently over the tops – within a week, they were putting on good leaf growth and weren’t bowing, sure signs of recovery.

However, if they are so weak that they prove impossible to pot on, cut your losses, throw them on the compost heap, sow again and put it down to experience.

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Mandy Watson is a freelance journalist and an incurable plantaholic. MandyCanUDigIt grew from the tiny seed of a Twitter account into the rainforest of information you see before you. Gardening columnist for the Sunderland Echo, Shields Gazette and Hartlepool Mail and editor of the Teesdale Mercury Magazine. Attracted by anything rebellious, exotic and nerdy, even after all these years. Passionate about northern England and gardens everywhere. Falls over a lot.


  1. Thank you for your tips about sowing seeds. I am sowing now in different places as experiments. I am using plastic box from old fridge as a cold frame in the backyard. I have them each protected by plastic bag as slugs can get in. I have some on inside windowsills. I have Aubrietia, Echinacea and Rudbeckia on the go. I am going to place some pots in the garden where I do the voluntary work. I will let you know the results. I think this is pot luck. John

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