Why and how should you thin out your seedlings (carrots, spinach, turnips, etc.)?

Thin seedlings when they are too crowded to develop properly. This may be useful outdoors, in trays or pots, but is unnecessary when plants already have enough space. Judge density and development rather than using the same timetable for every crop.

Thinning, an essential step

Seeding is an essential stage in getting your vegetable garden off the ground. Whether for a conventional garden or for permaculture, most plants that tolerate transplanting are first sown in terrines, trays or directly in the ground for the others. The important thing is to provide them with optimum conditions: light, heat and water. Seed packets are often well-stocked and gardeners can be heavy-handed. Sometimes, it's not even the gardeners who are at fault, but the ants who like to steal the seeds and pile them up. The result is sparse seedbeds on one side and overcrowded ones on the other.

The problem is that there's nothing positive about sowing too densely. The seeds stick together, the plants mix and the work of thinning out becomes a real headache. However, it is essential, because lack of space means that the seedlings cannot develop properly. We've all had to deal with radishes or carrots that were deformed because they were growing too close together. In the same way, foliage and flowers will have a hell of a time developing because the presence of too many plants doesn't allow the nutrients to feed each plant properly.

How to thin correctly

Start when seedlings are developed enough to identify and handle, often around their first true leaves. Do not automatically wait three weeks or a month if plants are already crowded. Keep healthy seedlings at the spacing recommended for the crop, variety and intended harvest size instead of using one universal distance.

Lightly moisten dry soil without soaking it. Remove surplus seedlings gently. Where roots are intertwined, snip unwanted plants at soil level with clean scissors to avoid disturbing the others. Carrots and parsnips dislike disturbance to their main root: do not rely on transplanting pulled seedlings. Only transplant young, healthy seedlings of crops that tolerate it. Check density again as plants grow.

Sow better to thin less

If thinning is a real chore for you, which it can be, especially when growing large rows of carrots or radishes, you can use tools such as the hand seeder, which allows you to control the seeds.

Another useful tip is to mix the seeds with fine sand to obtain a less dense sowing. This technique is particularly useful for very fine seeds such as fennel, basil or even chives.

What to do with removed seedlings

Healthy seedlings can go into compost or provide a thin layer of plant material in an appropriate place. Keep diseased material apart and do not leave removed plants covering the seedlings you are keeping.

Do not automatically treat thinnings as edible sprouts. Plant identity, seed treatments and growing conditions matter. For this gardening task, compost healthy thinnings. Grow edible young shoots separately using seeds and conditions intended for that purpose.