Today's Edition Local Missouri Opinion Obits Sports GoMidMo HER Magazine Events Classifieds Newsletters Election '22 Contests Jobs Special Sections National World

Ask a Master Gardener: Thin seedlings for healthy development

by Peter Sutter | May 22, 2022 at 4:00 a.m.

Probably one of the most difficult chores in the garden is thinning the seedlings, and therefore, it is the most often neglected task. If you are like me, you hate to destroy anything good growing in the garden, but I have found the results worth the heart-wrenching experience.

Thinning seedlings is necessary for healthy plant growth and development. It helps to maximize crop production and flower size. It also helps improve air circulation, which helps prevent fungal diseases. Of course, there are always exceptions to every rule, and there are some types of plants that tolerate a little crowding -- but tolerate is all they do. Every type of plant benefits from proper spacing.

If you haven't the heart or the patience to thin the seedlings, space the seeds properly at planting time. There can be a problem with this plan -- germination is rarely 100 percent, so there will likely be gaps in your row of crops or flowers. Thinning is really the best method.

Every plant has a recommended spacing. Most of the time, it will be listed on the seed packet. If you saved the seed package, look there; if not, you can refer to University of Missouri Extension publication G6201, Vegetable Planting Calendar. It is a free download at their website.

Seedlings should have at least two pairs of true leaves and be about 3-4 inches tall before thinning, but don't wait too long to thin the seedlings. If you procrastinate too long, the intertwining roots may cause damage to the remaining seedlings during the thinning process.

That being said, no matter what stage your plants are in, if your plants are too crowded, now is a good time to thin them. Snipping them off at ground level is a good method when the plants are larger.

You can also use scissors to snip smaller seedling off at ground level. This works very well with seedlings like carrots or lettuces. However, some plants may try to regrow if the roots are left in the ground.

If possible, evening hours are a good time to thin seedlings as the cooler temperatures and darker conditions make it easier for the remaining seedlings to bounce back from any stress they may have received. I have found cloudy days to be just as good.

After thinning your plants, water the remaining ones. This helps re-distribute soil around the roots. If the roots of the remaining plants are exposed, add or rearrange the soil to cover them.

It is also important to give seedlings and plants growing room in container gardens. Container plants live their entire lives in a limited space. The plants draw upon limited moisture and nutrients in the soil of the containers.

Successful gardening, whether in open space or a container, begins with proper plant spacing. I often plant crops like beets extra thick purposely and then use the plants I thin in salads or cooked greens. Whatever the reason, just do it -- you'll be glad you did.

Happy gardening!

Peter Sutter is a life-long gardening enthusiast and a participant in the MU Extension's Callaway County Master Gardener program. Gardening questions can be sent to [email protected]

Print Headline: Ask a Master Gardener: Thin seedlings for healthy development


Sponsor Content


Recommended for you