March, north of the equator

March is when a gardener stops reading and starts sowing. The soil begins to warm, the light is properly back, and both the garden and the windowsill move from dormancy into growth within a few weeks of each other. It is also the month that punishes impatience most reliably, because a warm week in early March is not spring.

In the garden

Sow the hardy things directly where they are to grow: broad beans, peas, spinach, rocket, radish, early carrots, beetroot and the first lettuce. Test the soil with your hand rather than the calendar. Cold wet ground rots seed, and a fortnight’s wait costs nothing because a later sowing catches up.

Start the tender things under cover. Tomatoes, courgettes and cucumbers are all better sown now indoors and planted out when the frosts have gone. Sow cosmos, sunflowers, nasturtiums, pot marigold and sweet peas, and start dahlia tubers in pots in a greenhouse or a bright shed.

This is the last month for bare root and the first good month for planting from a pot. Hydrangeas, hostas, ferns, boxwood and jasmine all go in well now, and hostas can be lifted and divided as the shoots appear. Plant lily bulbs if you did not in autumn, and cut the old growth off ornamental grasses before the new blades push through.

In the house

Repot now. This is the one month of the year where the answer to should I repot is simply yes if it needs it. Roots out of the drainage holes, a pot that dries within a day, or water running straight through are all the sign. Go up one size, use fresh compost, and water once properly.

Start feeding as growth appears, at half strength for the first month. Shorten the watering interval gradually rather than all at once, because the plant is only just waking and the compost still dries slowly.

Move plants back from the brightest glass if they spent winter pressed against it. March sun through a south window is strong enough to scorch a leaf that has spent four months in low light, and the mark it leaves does not fade.

What not to do yet

Do not plant out anything tender. The last frost is weeks away in most of the country and a single cold night will finish a courgette. Do not be tempted by the bedding on sale outside a supermarket in the second week of March either. It has been raised under glass and it has no idea what a frost is.