Growing vegetables from seeds is much less expensive than buying nursery seedlings, but it's also slightly more work. Many gardeners plant vegetable seeds—especially the tiny ones—simply by sprinkling them in loose rows along the soil. As they sprout, seedlings are often spaced too close together. So gardeners must systematically pluck out enough seedlings to allow the remaining plants room to grow. Thinning seedlings produces healthier plants and higher yields by reducing competition for water and nutrients and providing good air circulation between plants. There are a few simple steps to follow to make sure this process is successful.
When to Thin Vegetable Seedlings
Seedlings are usually thinned once they have one to two sets of leaves. Most will be 2 to 3 inches tall by then, making them easy enough to grasp and pull. If you prefer to pull your seedlings over cutting them with scissors, thinning while the soil is damp will make it easier to slip them out without turning up everything nearby. In addition, thinning in the evening gives the remaining plants a chance to adjust before being exposed to heat and sunlight.
Equipment / Tools
- Kneeling pad (optional)
- Garden scissors or nail scissors (optional)
- Flexible rake (optional)
Determine Desired Spacing
Seed packets will usually give recommendations for the spacing between plants, which you can follow for thinning once you have seedlings. In general, leave the anticipated size of the mature plant plus a couple of inches around your seedling. Spacing recommendations for common vegetable plants include:
Remove Unwanted Seedlings
Seedlings can be easily plucked with your hands, simply by gripping them between thumb and forefinger and tugging. This is easiest when the soil is moist and pliable. If you prefer to avoid disturbing the soil (and nearby plants) by pulling out seedlings, then you can use scissors to cut off the unwanted seedlings at ground level.
Thinning long rows of seedlings entails a lot of work close to the ground. So a kneeling pad can be a helpful tool to keep you comfortable.
Thin by Rake (Optional)
If you are growing vegetable seedlings in blocks rather than rows, you can try running a flexible rake through the seedlings to thin them. Plants won't be perfectly spaced. But this process will open up more space for them to grow, and it's much faster than plucking or cutting off seedlings by hand.
Water the Survivors
Thinning can disturb the soil, so it's best to lightly mist the remaining seedlings after thinning. This will help to rejuvenate the plants.
Tips for Thinning Vegetable Seedlings
Seedlings started in pots usually don't have to be thinned because you can separate them when it's time to transplant outdoors. But plants that are directly seeded into the ground almost always require thinning.
How many seedlings you take out—and the spacing you allow for the remaining seedlings—will depend on whether you want your vegetables to grow to full size or you prefer to eat them early. For example, if you like to harvest tiny carrots, you can leave the seedlings tightly spaced. But if you prefer large carrots at the end of the season, the spacing should be much farther apart.
Root vegetables can be sensitive to thinning because disturbing the young roots can cause deformation. Also, transplanting long-rooted vegetables, such as carrots and turnips, can cause them to fork. So carefully pull one seedling at a time, or try cutting the unwanted seedlings at the soil line. That way, you shouldn't disrupt your wanted plants.
Finally, some people find it difficult to sacrifice so many vegetable plants. The good news is some seedlings, including lettuce, beets, and spinach, can be harvested and tossed into salads or other recipes at any time, so all is not lost.