What is Thinning?
When growing vegetables by seed, gardeners use thinning as a technique to maximize germination and production. Since seeds are cheap and abundant, a common technique when planting seeds, rather than seedlings, is to ‘over-seed’ – to plant more seeds than you desire to grow in a specific location. This will ensure you have all the plants you want growing and more. Once your seeds have begun to grow, pull or cut the extra (and weakest) plants until you have the desired number of plants growing at the desired spacing. This technique is most commonly used for root vegetables and is also often used for greens that may be sensitive to bolting.
This photo shows thinned carrots on the left with adequate spacing and carrots on the right that still need thinning. Take a look at our YouTube video titled, “How to Thin Carrots” to see thinning in action.
When to Thin:
Thinning should occur once plants have established about two sets of true leaves. This will have given your plants enough time to grow sufficient roots to keep them in place if surrounding plants are pulled. Thin after watering in order to lessen the stress placed on the remaining plants in case their roots are disturbed.
How to Thin:
You can thin your plants by simply pulling them out of the ground or by clipping the stem just below the surface of the soil.
Vegetables that are Commonly Thinned:
Carrots, Beets, Turnips, Radishes, Parsnips, Spinach, Cilantro.