While the sun shines?

Christopher Lloyd's garden at Great Dixter is renowned for the planting effects he achieves by using quick-growing annuals that flower through the summer. Here he gives some tips on some of his favourites and shows why now, rather than earlier, is the time for sowing their seeds

There are several advantages in sowing the seeds of annual flowers in May rather than earlier. First, the season is on your side. Best to sow them in containers under glass, but nothing more than sun heat will be needed.

Once established the seedlings, either pricked out into seed trays (I generally prefer a wide spacing of 7 x 4) or potted individually, will not need to be kept waiting before they can be planted out. So there is no worry about their becoming starved or cramped before they get into the garden. Third, there are a number of rather tender annuals that are far more easily handled after a late sowing.

I like to sow dahlias for bedding now. If they catch cold, from premature hardening off, their leaves turn yellow and they remain thoroughly miserable for a long while. A strain I am growing this year, and have enjoyed before, is Collarette Dandy (from Thompson & Morgan). The flowers are semi-single but inside the outer rays is a ring or collar of petals of reduced size, often in a contrasting colour.

Sown in mid May, the plants will be right for planting out in mid July and will already be showing flower buds. They will make a good follow-on to foxgloves, Canterbury bells or sweet williams, among others. If I remove the spent flower heads (and a length of stalk behind them, for the sake of looks) fairly regularly, I shall have them flowering for three months.

Zinnias are also best sown in May. They'll germinate in a matter of four days. Grow them in individual pots. I like the largest growing, dahlia-flowered kinds, like Giant Double mixed (Suttons). They will grow to 3ft and have a wonderful range of colours. Again, they hate to be cold in the early stages. I am also growing a dwarf (1ft) strain called 'Chippendale', in which the fully double flowers are mahogany brown but the rays are tipped orange. It flowers for ages.

Closely related to Zinnia is Tithonia rotundifolia 'Torch' (5ft) (from Chiltern Seeds). Its single flowers are brilliant, pure orange. This is a far more imposing plant than the smaller, more cramped-looking 'Goldfinger'. Three plants spaced 3ft apart will make a good patch. Give each plant a stake and a tie when it has reached about half its full height.

Salvia coccinea 'Lady in Red' (2ft) is far more elegant than S. splendens, which is the normal choice for bedding in public gardens. 'Lady in Red' contrasts well with the purplish-blue Salvia farinacea 'Victoria', though that is a little slower off the mark as to when it starts flowering effectively.

An annual climber that gives everyone a thrill is the dazzling morning glory, Ipomoea tricolor 'Heavenly Blue' (Chiltern Seeds). That loathes cold but can be planted out in late June or you can grow it in pots throughout its life – just sink the whole pot into the soil. It crumples up at midday, so you need to spend some mornings at home.

Coleus hybrids, usually grown as pot plants for the amazing range and patterns of colour in their leaves, are excellent bedding plants for late summer and up till the onset of cold weather. Sowing them in May (preferably early), I grow three seed strains from Thompson & Morgan, pot the seedlings individually, growing them on under cold glass and then plant them out in early July, deciding then how to arrange them for leaf colour combinations. Some sort of grouping is advisable so that the result does not look fidgety. Coleus are good in a shady border, if the ground is in good condition and there is moisture available.

I also sow marigolds and Cosmos bipinnatus (the Sonata strain, this year) in May, not because they would not flourish from an earlier sowing but because they develop so very quickly.

Christopher Lloyd’s garden at Great Dixter is open to the public.

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