What to do now: greenhouse

Reproduced from February 07 issue of Gardeners' World magazine. This month's issue on sale now Subscribe now by direct debit and save 25 per cent.

Divide primroses...dahlia tubers...seed tips...

4 steps to...dividing Cape primroses
After two or three years, I find the flowering performance of my Cape primroses (streptocarpus) starts to decline. You can propagate new ones from leaf cuttings or divide older plants to make new ones. Follow my step-by-step guide to divide yours and pot on into larger containers as plants develop next summer

1. Gently remove the plant from its pot and clean it up by pulling off old, dry flower stems and leaves..
2. Use a sharp knife to cut large plants into two or more pieces, each with leaves and a section of roots.
3. Plant each section into its own small pot using a multi-purpose potting compost and water in well.

4. Dividing older plants helps rejuvenate them. Feed them weekly and keep in a warm, bright spot.

Tips for seed-sowing success Good hygiene is essential when sowing seeds. Either wash old pots and trays thoroughly or use new ones. Sow into fresh seed compost and don't use old bags of multi-purpose. . Water compost with a solution of copper fungicide, such as Bio Cheshunt Compound, to prevent dampingoff disease. . Water seedlings with tap water - not rainwater from a butt, which could carry disease. . Pay attention to the temperature. Seeds need warmth to germinate, so invest in an electric propagator. Be dazzled by dahlias
Buy dahlia tubers now to plant in pots and trays. Ready-potted plants will be available later in the spring, but tubers are usually cheaper. Make sure they are firm, and not soft or showing any signs of rot. Pre-packed ones hanging in warm shops often dry out and are unlikely to grow. Plant the tubers at once and keep them in a warm propagator or greenhouse. And remember, dahlias are frosttender and cannot be planted outside until later in May.