Mulch borders generously
The best time to put down a mulch is whenever you get round to it, because the pros of a good organic mulch – which are weed suppression, moisture retention and improved soil structure and fertility – always outweigh any cons, such as suppressing ‘little treasure’ seedlings. However, we do try to mulch all our borders in January because this gives time in autumn for the borders to die back gracefully, and allow birds to eat all seeds and berries, but is also early enough not to suppress the growth of bulbs such as alliums and tulips that start to appear by the end of February.
Whenever you mulch, the same rules apply: use a well-rotted organic material such as mushroom compost, garden compost or bark chips (we use pine bark on the grass borders for a little extra acidity) and be generous with it. Spread the mulch at least 10cm thick around all existing plants. In principle, the thicker the mulch, the better it will do its work, so it is more effective to mulch half the garden every other year well, rather than all of it annually but inadequately.