June is extremely important for winter garlic, because during this period the formation of its future head begins.
What size the head will grow can be judged already now by looking at the above-ground part of the crop.
If the neck is thick and the leaves are wide and tall, then the harvest will certainly please you, but in the opposite situation, the result of growing garlic will be sad.
In this case, you can't delay with fertilizing, but it's too late to build up green mass in mid-June, so you shouldn't even approach nitrogen. Green manure is also prohibited.
Instead, get yourself a solution of fresh wood ash extract.
Pour 9 liters of boiling water over 1 liter of sifted wood burning residue, then mix thoroughly and leave for 2-3 days so that the solution can infuse properly.
After the specified time, the mixture should be filtered and 150 ml of 9% vinegar should be added.
Alternatively, use Kalimag, and after a week use potassium monophosphate. In both cases, you need 30 g of the preparation per 10 liters of water.