Asters provide something to look forward to in the second half of summer

Our recent spate of long, frost-free autumns has suited asters' pattern of growth, says our gardening expert

In the pink: The classic aster, Milady Mixed (Getty Images)

When the wall first came down in Berlin, shopping trips seemed to be all in one direction. East Berliners staggered home across the divide laden with more carriers than a bag-lady. Food and modern electronic gadgetry seemed to be top of their shopping lists, but when trade with Eastern Europe started in the opposite direction, one of the unexpected arrivals was seed of garden flowers that we in the West had once had, but which had been long lost.

Very little seed breeding took place under the various Communist regimes of Eastern Europe; flower seed never featured on anyone's five-year plan. During those cut-off years, gardeners in Eastern Germany, Poland and Hungary went on growing and saving seed of the flowers they'd always had.

In the early Nineties, Mr Fothergill's re-introduced a twin-tone aster from Eastern Europe which had disappeared from English seed lists after the First World War. It was a pretty thing, double flowers of red or blue, with a thick band of white round the edge of each petal. The plants branched more freely than our modern asters and grew to a useful height – about 56cm/20in high.

You can still find them listed by a Polish seed company, W Legutko (look for item 064.600 at legutko.com.pl) but they didn't last long in English seed catalogues. Thank heavens not all gardeners are as fickle as we are. The Brand New Variety trumpeted in Mr Fothergill's 2015 catalogue is an aster called Valkyrie Mixed (£2.29 for 100 seeds); it flowers up to 14cm across, with quilled petals in a range of soft, chalky pastels. I like asters and they usually feature somewhere in the garden. It is good to have something fresh to look forward to in the second half of summer, and our recent spate of long, frost-free autumns has suited their pattern of growth. So I'm planning to give 'Valkyrie' a whirl, along with the classic 'Milady Mixed' (Thompson & Morgan £2.69 for 150 seeds).

Unlike many annuals which flower better when half-starved, asters like a rich diet. My gardening bible, Beeton's Shilling Gardening, published in the 1890s, recommends copious draughts of manure water, food and drink in a single potion. Any modern liquid feed will have the same beneficial effect.

They do best in deep, rich, light soil in full sun. Sow the seeds during the first week in April, and germinate them at a temperature of 15-20C (60-68F). Prick them out into individual small pots and grow them on until they are sturdy plants, ready for bedding out at the beginning of June. Beeton recommended them highly for a ribbon border, a must-have in the Victorian garden. A ribbon border in the old style would look wonderful in the front garden of a Victorian terraced house.

Asters are useful to follow on from snapdragons, which tend to rest (or give up completely) at about the time that asters are getting into their stride. Snapdragons last longer in gardens where there are not small children. The flowers were never designed to open and close as often as they oblige them to, squeezing the sides of the lippy petals so that the bottom one gapes open and shut like a goldfish out of his element.

Sow the seed in early March, scattering it very thinly on top of the compost and covering it with a layer of vermiculite. Seedlings seem to do better in low-nutrient composts, so use a John Innes No 1 rather than a multi-purpose. Germination takes between 10-14 days at a temperature of 15-20C (60-68F ). It can be erratic, so do not give up hope. Prick out the young plants and grow them on in the usual way. Pinch out the growing tips when the plants are 8-10cm/3-4in high. This will force them to make more flowering spikes.

Rust is the most irritating fault of snapdragons and so-called resistant varieties are not always as free from it as their champions claim. The spores affect leaves and stems which erupt in a rash of dark-brown pimples.

Some snapdragons have wine or bronze foliage, which doubles their effectiveness in certain kinds of planting schemes. 'Black Prince' (T&M £2.99 for 750 seeds) is a very old variety with deep burgundy flowers above bronze foliage. But I'm also going to try 'Bizarre Hybrids' (Sarah Raven £1.95 for 300 seeds) which has extraordinary flowers, purple and marbled with red and cream. That sounds hideous, but the picture in the catalogue looks wonderful.

Aquilegias self-seed like weeds in our garden and I spend a lot of time digging them up. But there's a very pretty species Aquilegia caerulea (T&M £2.99 for 100 seeds) that I want to re-introduce this year. It is a native of the Rocky Mountains, with flowers of clear sky-blue, taller than Aquilegia alpina which has flowers of a similar blue. Last year I saved seed from a bought plant of Aquilegia flabellata, a Japanese species. It germinated like mustard and cress and I raised three rows of plants. This year I will know whether they are true to form or not.

I prefer to sow seeds such as aquilegia in summer rather than spring. Apart from anything else it spreads the load. There is plenty else to be looking after in the seed line in March and April. The plants grow best in slightly damp soil and are happy in dappled shade. Even if you sow in spring, you cannot have plants flowering in the same year. But once they are established, they will be with you for a long time.

Cobaea, a fast-growing climber, is hardy in its native habitat (Mexico) but we have to grow it as an annual. A packet of seed should be included with every house conveyance, for nothing else gives such a showy effect so quickly in a new garden. It grows 7m/20ft or more in a season, hanging on to supports with pea-like tendrils that grow from the ends of the leaf stalks.

The flowers are cup-and-saucer shaped, the cups a rich purple, the saucer calyx an almost translucent pale green. It is excellent as quick cover on the poles of a new pergola, to cover a trellis screen or to cover up the evidence of a sudden winter death.

The best germination comes from home-saved seed, which can be sown fresh. But T&M have it (£2.99 for 9 seeds), as does Mr Fothergill's (£3.19 for 20 seeds). Sow the seeds on edge in damp compost, one to a 8cm/3in pot. Seal the pots in clingfilm. The seeds will have sprouted in three or four weeks. April is soon enough to sow, as the plants cannot be set out until the end of May. They need to be hardened off carefully. Do not plant them next to anything winsome. These plants are Wagner not Chopin.

Seed is available from Mr Fothergill's (mr-fothergills.co.uk); Sarah Raven (sarahraven.com); Thompson & Morgan (thompson-morgan.com)

WEEKEND WORK

WHAT TO DO

* Several different herbaceous plants, such as papery-flowered romneya, oriental poppies, anchusas, perennial verbascums and gaillardias, are most easily propagated by root cuttings taken this month. Dig up the clump you want to increase, chop up the roots into pieces between 2-5cm in length and push the cuttings vertically (right end up) into pots full of a sandy light compost. Cuttings of romneya and gaillardia are best laid thinly over the surface of a tray of compost and then covered with another layer of compost about 50mm thick. Put the pots and trays in the greenhouse (or a cold frame) and keep them watered but not drowned. By early June, you should have young plants sturdy enough to be grown on in a nursery bed.

WHAT TO SEE

* The RHS has axed the best of all its shows – the mid-January one that used to be staged at the Horticultural Halls in London's Greycoat St. But lovers of hellebores can instead visit the famous Ashwood Nurseries, Ashwood Lower Lane, Ashwood, Kingswinford, West Midlands DY6 0AE where on 24 Jan between 10.15am-2.30pm you can take a guided tour of owner John Massey's extensive collection. Tickets cost £2.50. No need to book; proceeds go to charity.