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when to thin seedlings

How to Thin Vegetable Seedlings

  • Total Time: 1 hr
  • Skill Level: Intermediate
  • Estimated Cost: $0

Growing vegetables from seed is much less expensive than buying seedlings from a garden center, but growing from seed also slightly more work. To save time and effort, many gardeners sow vegetable seeds—especially seeds that are very tiny—simply by broadcast sprinkling them in garden beds rather than sowing each seed individually. As a result, too many seedlings sprout and are packed too closely together.   When this happens, gardeners must systematically remove the extra seedlings to provide enough space for the remaining seedlings to grow. Thinning seedlings produces healthier plants and higher yields by reducing competition for water and nutrients and providing good air circulation between plants. Follow these few simple steps to thin seedlings.

When to Thin Vegetable Seedlings

Seedlings are usually thinned when they have one to two sets of leaves. Most plants will be 2 to 3 inches tall by then making them easy enough to grasp and pull out.   If you prefer to pull your seedlings rather than cutting them with scissors, thinning while the soil is damp will make it easier to slip them out without disturbing everything nearby. In addition, thinning in the evening gives the remaining plants a chance to adjust before being exposed to heat and sunlight.

What You’ll Need

Equipment / Tools

  • Kneeling pad (optional)
  • Garden scissors or snips (optional)
  • Flexible rake (optional)

Instructions

Determine Desired Spacing

Seed packets will usually provide appropriate guidelines for seed sowing depth and spacing. In general, plants should be spaced based on their mature size plus a few inches. Here are spacing recommendations for a few commonly grown vegetables:

  • Beets: 3 to 6 inches
  • Carrots: 2 to 3 inches
  • Lettuce: 18 to 24 inches
  • Onions: 3 to 5 inches
  • Parsnips: 3 to 6 inches
  • Radishes: 2 to 3 inches
  • Rutabagas: 8 inches
  • Spinach: 2 to 6 inches
  • Turnips: 2 to 4 inches

Remove Unwanted Seedlings

Seedlings can be easily plucked with your fingers simply by gripping them between your thumb and forefinger and giving a gentle tug. This method of removing seedlings is easiest to do when the soil is moist and pliable. If you prefer to avoid disturbing the soil (and nearby plants), you can use garden scissors or snips to cut off the unwanted seedlings at ground level.

Thinning long rows of seedlings requires bending and working close to the ground. Thus, 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 run a flexible rake through the seedlings to thin them out. However, the seedlings won’t be perfectly spaced. Raking will free up more space for remaining seedlings to grow and is much faster than plucking or cutting seedlings by hand.

Water the Survivors

Thinning can disturb the soil, so it’s best to lightly mist the remaining seedlings after thinning 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 them outdoors. However, seeds that are directly sown 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 if you prefer to eat them early. For example, if you like to harvest tiny carrots, leave the seedlings tightly spaced. But if you prefer large carrots at the end of the season, the spacing should be much farther apart according to the directions on the seed packet.

Root vegetables can be sensitive to thinning because disturbing the young roots can cause deformities. Also, transplanting long-rooted vegetables, such as carrots and turnips, can cause them to fork. So, to thin root vegetables, carefully remove one seedling at a time, either by gently pulling it from the ground or cutting it at ground level. That way, you shouldn’t disrupt the remaining plants.

Finally, some gardeners find it difficult to sacrifice so many vegetable plants. The good news is that some plants—like lettuce, beets, chard, and spinach—is that you can toss the tiny seedlings you remove into salads or other recipes, so all is not lost.

Seeds often sprout too close together and need to be thinned to have space to grow. Learn when and how to thin seedlings.

Thin Seedlings without Cutting Them

Once your seeds sprout you will need to thin them. Many garden sites will have you cut out seedlings to thin them but what a waste! You can easily thin your seedlings without resorting to killing off any little plants. I show you how.

How to thin seedlings without cutting them. Seed starting is so fun and you can get tons of plants for very little money. But what if you seeded too thickly or many more of your seeds sprouted and they are getting crowded?

Many recommend snipping off some seedlings but I show you how to can thin out your plants and keep them all alive. No need to sacrifice any.

I have started seeds for many years. I have followed the advice of many garden gurus and cut off the extra seedlings that sprouted to let one grow bigger and stronger. But it was so HARD to kill perfectly good plants that struggled to sprout and were growing well.

Geranium Seedlings to be Thinned

When I sowed these geranium seeds I thought they were too old to germinate so I sowed them thickly. I was wrong about them being too old, many came up in the same cell.

I don’t always use these six pack containers to start seeds in. Much of the time I start a bunch in a single tub or container as I did with these tomatoes. I like using recycled containers as much as I can.

Some of these tomatoes were very close together and yet I did not cut any. I gently eased them out of the soil (a very loose mix helps tremendously) and pot up into individual pots for them to grow on.

Watch this video to see how I do it. It is super easy and I have 100% success rate.

Why Some Cut to Thin Seedlings

Some will claim that you shock the plants or it kills some but I have not had that happen to me. I have done this for over a decade now and don’t have any problem. I have even done side by side trials where one set I cut out the extras and let one grow on and in the other I did this method I share today. There was NO difference other than I saved a ton of plants I did not have to kill.

Here is my photo step by step to Thin Plants

Here is a recycled mixed salad container with pansy seedlings in it. You can see they are growing close together. They have their true or secondary leaves so they are ready to prick out and pot up.

Don’t worry that it will hurt them or restrain them from growing healthily. If you are gentle enough they should do just fine.

In the video I showed this technique on Geranium seedlings. This works on most plants.

Tools to thin your seedlings

I use an old paring knife I keep in the greenhouse but you can use a pencil, a skewer or just about anything that is small enough.

Your goal is not digging, it is loosening the soil at the roots as you lift the seedling.

How to Dig out the seedlings

This is also called “pricking out”. Grasp the seedling by a leaf, not the stem. Sink your digging tool, in my case the knife, into the soil beside the seedling and gently lift as you pull on the leaf.

Wiggle the knife as you oh so gently tug on the seedling to help loosen it.

It will pull free and have a beautiful little root.

Sometimes you will get more than one to come out, just gently untangle the roots from each other. If you are careful it won’t do any harm to either seedling.

Pot up the pricked out seedling

I have these 3 inch pots that I use for the tiny seedlings or you can use recycled 4 inch pots you may have saved from plants you bought at the garden center. Since I tend to get a lot of plants started and run out of room, these smaller pots need less space. they last a long time, I have been re-using these little pots for the past 10 years.

Scoop up some potting mix into your pot, I will share my homemade mix soon, so subscribe to get the updates if you want to be notified. There is a button at the top of this page where you can do that.

Place your seedling on top of the potting mix in the little pot and press it down into it softly. The mix should be loose enough that it will not need much pressure.

Add a bit more potting soil to fill in the indentation from your finger and set aside.

Seedling care after thinning plants

Once I have them potted up I water them well. I let them sit in the tray beneath and let them soak up the overrun.

Do not put the freshly potted up seedlings in the direct sun. Mine stay in the greenhouse or if they are very tender annuals I put them back on my seeding rack indoors.

With the tender annual seedlings I keep them inside until the nights stay above 40 degrees for the most part. My greenhouse is more of a large cold frame, it is not heated and can get quite cold if the night time temps dip into the 30s.

I start feeding them a weak solution of this Seaweed based water soluble fertilizer. I mix it half strength and use each time I water the seedlings. Many will claim you do not need to feed the seedlings yet but I have found mine do better when I use it. Here is some info on it from Gardeners

So what seeds did you start this year?

Here is my video on YouTube. Have you subscribed yet to my YouTube?

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Once your seeds sprout you will need to thin them. Thinning seedlings is easy and no need to cut any! I show you how one easy step at a time.