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What do leggy seedlings mean?

If your seeds are growing tall, but falling over and not are not able to support their own weight, then you have leggy seedlings.

Having leggy seedlings is not the disaster you may think and can be salvaged. Seeds are leggy is that they are trying to seek out sunlight. So first of all you can acclimatize them to outdoors and try to get them more hours of daylight.

What does ‘leggy’ mean when it comes to seeds?

Leggy seedlings are not healthy seedlings. They are growing taller to try and reach the daylight. They will not be able to support their own weight and are in essence stretched. This is a really common situation.

In the UK we have what is called a ‘false Spring’ and it is followed by frosts and harsh weather. It is natural to get your seeds in as soon as the packets say you can. Even under glass they can struggle to find the sunlight that they need.

leggy tarragon seeds

You can see from the seedlings above that some of them have collapsed and will not be viable. Once they have collapsed they will not be able to make the most of the sunlight so are not going to reach their full potential.

How to Save Leggy Seedlings

In short they will thrive when put outside. However you cannot rush to get them out. You need to acclimatize them to the cold. This means leaving them under glass outside overnight. There is still the protection from teh cold but it is not a full exposure.

We leave seedlings in the porch, garage or conservatory to get them used to the lower temperatures. It is a form of hardening off and can be achieved quite quickly depending on the plant.

The ones pictured are some of my Russian Tarragon. I did start them when it was sunny, but will now transfer to the outside. By putting into their own pots I can then cover with a cloche and allow them to thrive in the full days sunshine.

The red basil shown may be too late as they are a delicate herb and will need to be protected from the cold. At least with the woodier herbs you know they will be able to cope with cold winters. Caution should still be taken with seedlings though. Even the hardiest of perennials was delicate at first stages.

In theory once they have their true leaves most perennials will benefit from hardening off outside.

How to avoid leggy seedlings in the future

Being a gardener in the UK is a bit like being a poker player. You’ve got to know when to hold them and when to fold them. Do not be fooled by that sunshine in the sky, next week may be gloomy and your seeds will have germinated to be greeted by grey skies.

Just because the seed packet says you can grow them under glass from March, does not mean you should get them into the soil from the 1st of the month!

Using a grow light for seedlings

Grow lights are no longer just for high tech systems. You can have a light like the one below for less than the cost of a small tomato house. SO they are perfect for those with only small spaces outdoors.

A grow light can seem a little over the top, however they are reasonably priced and will allow for a longer growing period. An LED Plant Light will mean you do not need to rely on a windowsill for all of your seedlings. Therefore increasing the amount of seeds you can grow as well.

You will need a power source and an area to give over to the seedlings but it now becomes a lot easier as the one above has a timer on it. As long as you remember to keep the seedlings moist they should thrive. Then you will avoid any more over stretched and leggy plants.

How to save tomato plants

If you have leggy tomato plants you will need to be ruthless and only try to transplant the healthiest. By trying to save straggly young plants you will not be able to get mature plants that can healthily support the weight of their own fruit. They will therefore not produce the same amount of crop and you are investing a lot of time and energy into a smaller return.

Is it ever good to be leggy?

Cress is a prime example of when a tall shoot is great. We love to grow cress with the kids and find that it is one of the quickest herbs to grow. You will see great success even if they are not exposed to sunlight until the last few days.

This is because they are essentially just the first shoot. Like microgreens they tend towards height with just those first leaves to eat.

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