To sow or not to sow? When is the right time to sow seeds for the flower garden?

Cosmos 'Sensation mix'

At this time of year the spring sunshine is beginning to shine and you just want to get out in the fresh air and garden. But when is the right time to sow seeds to achieve that wonderful show of garden flowers throughout the year?

For us, sowing for this year began last June around the summer solstice. In mid-June we sow our biennials. These are plants that develop in the first year, grow on to develop good root systems and survive outside in the winter weather with few problems. Biennials will give a good early show of colour when they flower the following year. There are some wonderful flowers for cutting and fragrance in this group which include the foxgloves, Hesperis (sweet rocket), some Campanulas, wallflowers and of course Sweet William. Our biennials are ready for planting out into the flower garden by September so that they develop strong root systems to allow them to over winter.

Sweet William
Sweet William
Wallflower 'Blood Red'
Wallflower ‘Blood Red’

Our second sowing period is around the autumn equinox. By mid-September we like to have sown our hardy annuals. Hardy annuals are tough enough to over winter so that they are already decent sized plants by the spring. This gives you a head start and results in much earlier flowering. The aim is to sow your hardy annuals late enough so that they don’t try to flower before the winter but earlier enough that the plants are large enough to survive the cold. We tend to over winter most of our hardy annuals under glass but some can grow on outside quite happily. The hardy annuals we grow include the likes of Nigella, larkspur, cornflowers, corncockle, feverfew, Ridolflia and some annual Scabious. Antirrhinums and Bupleurum may not be considered hardy annuals but we find that they do over winter in an unheated greenhouse if you are lucky.

Nigella damascena
Nigella damascena
Larkspur 'Braveheart'
Larkspur ‘Braveheart’
Cornflower 'Blue Diadem'
Cornflower ‘Blue Diadem’

Our first sowing of half hardy and tender annuals is usually complete by the spring equinox. We get many annuals started indoors in the heat and grow them on under lights until they can be moved out into the greenhouse and polytunnels. These will not find their way out into the garden until after all risk of frost has passed. The list we grow is too long to include here but some of our favourites include Cosmos, Salvias, Amaranthus, Ageratum, Didiscus, Rubeckias, Malope and many many more.

Pictures of the flowers we grow can be found on our Pinterest Boards in the monthly flower libraries. After the spring equinox we will sow further batches to ensure that we get a good succession of both hardy and half hardy annuals. It is possible to sow directly into the ground when the ground warms up but we find we have too many failures that way. Instead we grow in trays and modules and plant out when the weather is kinder and the plants are well established.

Ageratum 'Blue Horizon'
Ageratum ‘Blue Horizon’

It is fair to say therefore that sowing does not really begin in the spring but instead in mid-summer and we find the summer solstice and autumn and spring equinox a good way to plan our year.


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