What seeds to buy online and where

Seed sowing is an art which makes gardening such fun. Now is the time to plan and order for the best possible summer. It is worth ordering because stores and garden centres carry an ever smaller sample of the seeds available from specialists. It is worth sowing not only for the fun of it but in order to have summer bedding plants which the stores will not be offering in May.

Sweet peas are the classic choice for seed sowers. One of the biggest and most fascinating lists is maintained by Roger Parsons in West Sussex, a holder of the National Collection of Sweet Peas. He offers more than 1,300 varieties and anyone who is looking wistfully for an “old-fashioned” favourite, scented species or exhibition variety will find it in Parsons’ excellent range. Catalogues can be viewed and orders placed online at rpsweetpeas@tiscali.co.uk.

Remember that all sweet pea seeds are best soaked overnight in warm water and then lightly chipped on their hard coating before sowing, five to a pot. They need heat if they are to germinate and, above all, they must not be starved of light. They will germinate in a dark, warm airing cupboard but they will not grow on inside this dark shelter. Lack of light is the cause of spindly, weak seedlings which never recover. As soon as they show above the soil, bring them out into full daylight.

I cannot resist a new pale sweet pea from Unwins called April in Paris (unwins.co.uk). It is probably no better than older ones but the name is so charming. If sown now, it will not be flowering in time for you to deliver an Easter bouquet by scooter to a female of your choosing. It flowers in the usual July slot but the name conjures up happy spring days. If you want a first-class dark blue sweet pea to go with it, try Thompson & Morgan’s very dark blue King Size Navy Blue, a superbly scented variety. The company’s excellent list of old and new varieties remains a primary stop for gardeners who shop online (thompson-morgan.com).

While you chase the Navy sweet pea, look also for the excellent Antirrhinum Royal Bride. I have had superb results from this variety for the past eight years, not least as a cut flower because it has such a sweet scent. The main spikes are long but as soon as they have been picked, side shoots develop on into autumn. I have never had a trace of the dreaded rust disease on this variety. Although the first flower stems take the height up to 3ft, I have been delighted with it in big pots too. A winner in every way.

Royal Bride is not one for an Elysée Palace bouquet but my next suggestion is. I was short of experiments last year and picked this off the seed racks only out of idle curiosity. Phlox Moody Blues turned out to be so much better than its silly name. It was the star of my bedding year. It is only half hardy, so it has to be germinated with heat, but it goes on flowering well into autumn and is excellent even in big pots where the loose stems will spill forwards over the edges. It is also superb in the front row of a traditional border. The name is a warning that it will have a coup de blues but not in a way that means it will have to be moved out. The flowers’ colour varies according to the temperature, being nearest to a deep blue when the air is cool. It has become an essential addition to my summer gardening. It is very easy to grow and last year continued to flower in September. Try bunching it with Sweet Pea April in Paris.

Those favourites of French gardeners, the zinnias, let me down last year. Their rough leaves look so unappetising that I did not spray them as usual before bedding out the young plants. Within a week they had been stripped down to skeletons by an uninvited bug. They recovered enough to flower slightly in autumn, but I am forewarning you so that you are not caught too. They need chemical protection.

By far the best zinnias are the ones with big flowers, none bigger than Benary’s Giant Mix from Chiltern Seeds (its 2014 catalogues, featuring hundreds of new varieties, are available now at chilternseeds.co.uk: a seed shopper’s heaven). This year Thompson & Morgan is offering the new prize-winner, Zinnia Pop Art Golden & Red. Its big flowers are golden yellow, speckled with dots of red. I very much like the look of its photos and am going to give it pride of place in one of my plans, pests permitting. Plants will not be available in garden stores in May.

I am never sure that well-known perennials will really ever do what seedsmen claim and “flower the first year from seed”. Usually the flower is a half-size spike at ground level. However, I am extremely pleased with the recent varieties of delphiniums from seed, especially Thompson & Morgan’s Centurion Lilac Blue Bicolour F1 hybrids. Their flower spikes are quite good in their first autumn but are excellent in subsequent years. My 2012 batch outperformed even the best named hybrids which I had bought as young plants for £6 each. It is essential to sow seeds of these delphiniums by late February in order to have flowers in their first year. It is worthwhile too because individual plants will turn up at high prices as if to tempt you in late June. For about £3 you can grow 20 of your own.

Tobacco plants, or Nicotiana, will also be in every shop in mid-May, brutally priced as pre-grown plants. Personally sown varieties are so much cheaper and more varied. Sometimes, big leafy plants of the 5ft-tall Nicotiana sylvestris turn up in shops, pot-grown at £2 each. A packet of 2,000 seeds costs only £2.69 and is so easy to grow in a greenhouse. Outdoors, these great features of the summer have tall stems with clusters of little drooping white flowers, but they are only at their best on deep rich soils. For fellow stony-garden sufferers, I find that the excellent South American Nicotiana Marshmallow is a much better bet. It grows up to 4ft and has graceful stems of small flowers, fading through shades of deep rose pink, pale pink and white. It is a superb bedding plant, well able to put on height during one season. It goes on looking good into October.

Lastly, an old friend to scatter around outdoors, especially in this post-traumatic year for its namesake. Under the seductive brand name “Cottage Garden Flowers”, seedsmen are repackaging the old Love-in-a-mist. Perhaps you prefer it under its old brand name, Nigella. It is such a delight when it takes naturally to your garden. By scattering seed about in April and leaving the seedlings to compete for a place in the sun, you can give gaps in your border a haze of sky blue flowers from Nigella in late summer. When happy, they will continue to self sow and reappear in subsequent seasons. Nigella prefers a cool, slightly shady place, but gardeners have not sacked her yet after years of familiarity. In 2014 I will be scattering her around with renewed mischief and enthusiasm.