Sow your long-lasting border-fillers now, says Ruth

The prime planting time for perennials is spring, when the soil is warming up and workable after winter’s onslaught, and autumn when it still holds the summer’s sun and is dampened by showers.

If you have spent this summer filling border gaps with short-lived annuals and want an easier ride next year, sow some perennials now.

Then you will have two options: either move the young plants out in autumn (and be prepared to fleece and cloche them through winter) or grow them on undercover (which will still require some nurturing) and plant them out in spring.

Our borders are slightly gappy this year and as I much prefer perennials to most annuals, I am going to raise a selection from seed to bulk out beds next year.
As with all seeds, you need to follow a few rules for the best results.

Always use new or well-washed seed trays or pots and fresh seed compost. More nutritious composts are too rich for delicate seedling roots and can do more harm than good.
It is vital to use clean equipment as seedlings are susceptible to diseases carried in old soil. This also applies to water, so use it fresh from the tap not drawn from a water butt. (If necessary, keep a small watering can for seed-sowing and nothing else).

Once sown, keep the seeds somewhere light and warm, but out of direct sunlight. Remove any covering or lid after germination to encourage healthy airflow and move the seedlings to individual 3in (7cm) pots of multi-purpose or John Innes No 2 compost once they are large enough to handle.

Grow them on and acclimatise them to outside temperatures before planting them in their final place.


Keep an old teaspoon in the greenhouse – they are invaluable tools for carefully lifting seedling rootballs out of their seed compost without damage or tearing.