It’s a sad fact that thinning is essential in order to give plants the space they need to grow. The trick is to sow enough seeds as an insurance against non-germination or death-by-slug, or bird, or cat. You need to begin the whole process of sowing, KNOWING that many of your babies won’t reach their full potential. This may make it easier to cull….sort of…but not much. There is nothing worse than removing perfectly healthy plants. The problem is that if you don’t, then none of them will thrive. Simples.
Different plants need different treatment when it comes to thinning them out, but the essential thing with all of them is to sow thinly in the first place, preferably singly, or in pairs, into modules, or individual Jiffy 7 pellets, so that you can easily pot the small plants on with minimal root disturbance.
Sowing in pairs is a good option as it will give you an insurance policy. When both seedlings come up, wait until they are a few cm high and snip the smaller one off at soil level with scissors. It’s important not to pull it out, as this could disturb the roots of the plant you want to keep.
If your seeds are too small to sow singly, then this option still holds good – sow as thinly as possible and snip all but one or two seedlings away in each module. Two seedlings, in either corner of a small module can then grow on for a while and eventually one can be pricked out and transplanted, avoiding wastage.
In the ground, sow thinly as before and when the seedlings are an 2-3cm tall, do an initial thinning by leaving one good seedling every 10cm and pulling everything out in between. Watering before you remove seedlings will avoid root damage to neighbours, and watering post-thinning is essential too, to settle the compost around the roots.
A second thinning (to whatever the packet instructs) can then ensue, when you feel the plants are strong enough to withstand transplanting and the removed plants can be re-planted elsewhere, which may make the whole thing a little less gut-wrenching (though not much, I admit).