Anna Pavord: Weekend work

What to do

Spears of early flowering Iris reticulata and crocus are already pushing through. If the earth looks sour, tickle the ground up around the bulbs and remove any seedling weeds.

Continue to mulch round herbaceous perennials, such as hosta and rodgersia, both of which are quite greedy plants. The mulch feeds, but it also suppresses weeds and gradually improves the texture of soil.

Keep greenhouses well ventilated so that air constantly circulates through them. There is a difference between circulating air and icy draughts. A temperature as constant as possible is what you are aiming for. Winter sun can build up a surprising amount of warmth in a greenhouse. If you close the vents in time at the end of the day, you can trap some of this warmth and keep down the amount of artificial heat you use.

Gently force batches of early spring bulbs by bringing pots of them into a cool greenhouse. Dwarf narcissi, hyacinths, crocus and iris all respond to this kind of treatment. When the flower buds begin to colour up, you can bring the bowls into the house.

What to see

Learn how to make willow wigwams at the Royal Horticultural Society's garden at Rosemoor in Devon on Thursday. They are perfect for sweet peas, but equally good for climbing French beans or clematis. For Christmas, I wound one of ours round with lights and hung it with ivy. Tutors Peter Earl and Lyn Edwards supply the material and you go home with a wigwam six feet high. The day starts at 10am, finishes at 4pm and the cost is £54. Rosemoor is at Great Torrington, Devon. For more information, call 01805 624067.