The Importance of Thinning Seedlings

Pea seedlings before being thinned.

 One of the most unpopular gardening jobs has to be thinning seedlings. Sweet, sensitive souls don't want to hurt their babies. The seedlings look so good right now! Why kill perfectly good plants? I hate to break it to you but proper thinning is absolutely essential for garden success. For those of you who grow fall greens (and you should), now is a pertinent time to be thinning your seedlings. 

What do I mean by thinning? Well, when you plant seeds you almost always plant more than you need. There is no guarantee that all of your seeds will sprout into plants so you plant more than you need. Hence, you also end up with more seedlings (baby plants) than you need. Therefore, you must thin them out to the spacing recommended on the back of the seed packet. 

But Why?

First of all, plants cannot grow any further if there is literally no room to grow. Picture how big the plant will be at full size. Most seed packets will have that information listed. The diameter of a large carrot is over an inch thick but if you have six carrot seedlings per square inch, clearly there is no way any of them have space to get to a decent size. Vining plants like cucumbers and melons need several feet to spread so must be spaced even further. 

Pea seedlings after being thinned. 

Second, there are limited resources in any soil. No matter how good your garden soil is, it can only hold so much moisture or nutrients. If your plants are too close together, then they will be fighting for the same resources. Instead of a few healthy plants thriving, you have a mass of plants on starvation rations. This is even more true in the fall when sunlight is more scarce than the spring or summer. 

Finally, air circulation is absolutely essential to preventing mold and fungus on your plants. (Fungi thrive on moist conditions) but there can be no air circulation if your plants are jammed together. If you fail to thin your plants out than your just asking for mold on your plants. 

The good news is, thinning is easy to do. Also, seedlings like spinach and kale can be replanted (carefully! don't let them dry out till established!) so they won't go to waste. You just can't do that with carrots because the roots will be messed up. 

Good luck with your garden!