Interim Seedling Care: Why, When and How to Thin Seedlings

by on July 4, 2012


When starting seeds, It is a common practice among many gardeners to hedge their bets and plant extra seeds in the event that some of them do not germinate as they should. While this can be an effective method to ensure enough seedlings, there are also times when the gardener is left with too many seedlings in too small a space. When this happens, you are faced with the need to thin your seedlings.

Why do you thin seedlings?

It may seem obvious to gardeners who have been at it for a while, but there is an important reason for thinning seedlings that you might not understand until you’ve experienced firsthand what can happen if you don’t. You might think that having two tomato seedlings start in a single pod will mean that you’ll get twice as many tomatoes, for example. The reality is that those two seedlings are already competing for water, light and nutrients and if you allows both to continue as they are, chances are that they will both be stunted as a result. It is possible that the stronger seedling will overpower the weaker, but by thinning out the seedlings early on, you are helping to make sure the plants you want to grow are getting everything they need.

When do you thin seedlings?

While the exact timing can vary, it is generally best to thin seedlings when they are between 1” and 2” tall. As mentioned above, doing so can ensure adequate water, nutrients and light for all of your plants.

How do you thin seedlings?

Thinning seedlings can be as simple as pinching off the smaller seedlings to reach the number and spacing  that is desired. While this is effective, some gardeners (myself included) prefer to take extra steps and salvage the thinned seedlings when possible and practical. I like to do this by carefully digging out the seedlings with a fork and when necessary, using the tines of the fork to help separate the roots. This can be especially helpful when working with slightly more mature seedlings from such plants as tomatoes or peppers, where the root systems are stronger and more likely to have wound themselves together.

{ 2 comments… read them below or add one }

allison July 4, 2012 at 11:43 AM

holy cow is it ever important to do this…totally will next year…struggled badly with the effects of avoidance…still got some but could’ve done better…thank you for the post that reinforces what I know now!!!


Michael Nolan July 4, 2012 at 11:49 AM

You’re welcome, Allison. Sorry you had a bad season but experience is by far the best teacher.

Best of luck in the future!


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