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The Bumble Blog - Part 6

The nepeta in the central bed has been cut back, and lavender ‘Grosso’ is in full flower. These two plants provide the ‘bread and butter’ nectar sources for the garden, either one being in flower almost continuously from May to October. This year however the lupins have performed particularly well. We could have renamed the garden Lupinland. The key is regular deadheading. We do this before the flower spike has completely finished, when about half has turned to brown seed pods. Slug damage is a common problem with lupins, but we seem to be relatively untroubled. Possibly the gravel paths surrounding the garden have helped repel invaders. Our enemies are small rodents instead.

Returning to lavender, there is no doubt that all lavender is popular with pollinators, but it is less obvious that some lavenders are more popular than others. ‘Grosso’ is an intermediate, or Dutch, lavender. These are a cross between English lavender (L. angustifolia) and Portuguese lavender (L. latifolia). They are an invaluable group combining the cold hardiness of English lavender with the heat tolerance of Portuguese lavender. In addition they are robust plants which typically flower over a longer period with larger flowers suitable for the cut flower market, and for oil production. More significantly for a bumblebee garden, when grown alongside English lavender they host four times as many insects per square metre as the English lavender.

Two other plants which have been admired in the garden this summer are Verbena ‘Bampton’ (V. officinalis var. grandiflora ‘Bampton’), and Lavatera trimestris ‘New Dwarf Pink Blush’. The verbena is a perennial plant with shiny near-black foliage and tiny pinky mauve flowers. It is striking and easy to grow. It sets seed freely but not all the seedlings will be as black as the parents, so select only the darkest ones. The mallow is also easy to grow, and produces large, flawless, clear pink blooms on plants about 60 cm tall.

It is late, but not too late, to be sowing biennials for next year. We have already sown foxgloves and wallflowers which will be pricked out and grown on in individual pots or cells until they are planted out at the end of the summer. Last year’s wallflowers flopped untidily but kept on flowering well into spring and remained popular with the bumblebees until the last flowers were gone.