Larkspur with a flying start

September 13th, 2019 | Plant Talk with Graham Rice | 0 Comments

Larkspur 'Giant Imperial Mixed'

This summer, my larkspur grew as tall as my delphiniums. They were amazing. And the reason for so much vigorous growth? They were self sown seedlings that germinated in August and September.

Germinating in warm soil, they soon got their roots down, developed plenty of attractive divided foliage through the autumn and winter and then surged into flower in late May and June.

So, learning the lesson, I’ve already sown some larkspur seed and the seedlings were through in just a few days. Of course, you can simply scatter the seed around as if it was self sown but there’s a better way.

Choose somewhere sunny and sheltered. If the soil is heavy, work in some old potting compost to open it up a little. Use the point of a stick, or your finger, to draw a drill (a shallow furrow) in the soil. Take the rose off the watering can then gently pour a stream of water along the drill, put your thumb over the spout to limit the flow. Gentle is good.

Sow the seed thinly along the drill. A packet of ‘Giant Imperial Mixed’ larkspur contains three hundred seeds. Don’t sow them all! In a 1.2m/4ft row you’ll only need fifty seeds. At this time of year the soil is warm and, with the moisture you’ve provided, the seeds should be peeping through in a week. Beware of slugs.

Sowing in rows makes it clear which seedlings are the larkspur and which are the weeds. Pull out the weeds.

In a 1.2m/4ft row you’ll only need about eight or ten seedlings, so remove some as they develop to ensure that they don’t become too crowded. If you grow ‘White King’ you’ll need fewer than if you grow ‘Giant Imperial Mixed’, you’ll need more seedlings of ‘Giant Imperial Mixed’ to be sure you get flowers from all the colours.

Keep them protected from slugs through the winter and late next spring you’ll be glad you sowed seeds now.

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Is one of our best known gardening writers. A graduate of the Royal Botanic Gardens, Kew, Graham was previously Gardening Correspondent of The Observer.
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