Fill gaps in your garden - sow flower seeds now

Sow flower seeds in March?

Yes, you can sow flower seeds in March. It may not feel like a peak gardening month but (slightly) warmer weather and longer daylight hours trigger plants to grow, leaves to unfurl and seeds to sprout. So join in, look ahead, and sow flower seeds to fill gaps in your garden and pots.

Warm soil is essential, so if you live in a chilly spot the soil may not be ready for a week or two. If you can, invest in some horticultural fleece to warm the soil in your garden and pots. Or sow seeds in pots and trays in a greenhouse or garden frame, in a propagator or on window sills.

Sunflower by Tony Hisgett. Licensed under the Creative Commons Attribution 2.0 Generic licence.

Sow flower seeds of 'hardy annuals'

These are the tough guys of flower seeds and perfect for gap filling. They are called hardy for a reason – they will stand more cold than ‘half hardy’ annuals (the soft stemmed bedding plants you must not plant outdoors before frosts are long gone). Hardy annuals like well drained soil, and some (especially wildflowers) prefer a poor soil.

When the soil has warmed up scatter the seed, and cover with warm soil, where you want flowers if you are sure weeds are not going to pop up soon. Add a label where you sowed or, in a few weeks time, a keen gardener will whip the lot out thinking they are weeds.

Or sow flower seeds in small pots or trays indoors or in a sheltered place in your garden. When the seedlings are about 2.5cm or more high move them very carefully, leaving soil attached to their roots, to their home. Water them in well after you move them. And add a label or that keen weeder may yet clear the lot!

Flower seeds to sow in late March: larkspur (Consilida), ‘love-in-a-mist’ (Nigella) and sunflowers (Helianthus) at the back of a border with candytuft (Iberis), pot marigold (Calendula) and ‘poached egg plants’ (Limnanthes) at the front.

A word of warning on annual poppies: they don’t like being transplanted so only sow a few seeds in each of a small pot, and when they are 2.5cm or so high, gently remove the lot from the pot and pop them into the soil where you want them to blaze with colour.

Top tip: sow flower seeds in a few large pots that can later be put into borders (pots and all) to fill unexpected gaps.

Flower seeds are good value. Sow flower seeds of hardy annuals and wildflowers to fill gaps in your garden and enjoy flowers through the summer. Sarah Buchanan

Plant perennials now

If the gaps in your garden seem too big for the hardy annual treatment, now is the time to plant perennial flowering plants. In September one of our blogs described how to make more of herbaceous perennial plants by dividing them into a number of plants. If you didn’t do it then, this is your last chance! Go on - ask your neighbour now for a chunk of the plant that you love so much. Prime candidates for this treatment are: hardy geranium, delphinium, phlox, aster and the RHS website suggests others to try. No plants to divide - head for the garden centre. They are filling up with flowering perennials. If you buy and plant a relatively small plant now it will grow quickly, saving you the cost of bigger plants and making gardening easier too.