Quick QUESTIONS
What are the li le black insects on my leeks? Linda Ti erton, by email Stefan says: Although the symptoms are not entirely typical, the tiny, narrow-bodied insects suggest to me that this is onion thrips, a common pest on members of the onion family but also occurring on many other kinds of plant. You don’t mention any flecking on the leaves which I might expect but in any event, control involves ensuring a rotation of all allium crops.
Why has my rose ‘Queen Elizabeth’ grown large but with few flowers? Karl West, by Facebook Stefan says: ‘Queen Elizabeth’ is a strong and vigorous rose but I suspect that your plant is having too much nitrogen. I suggest you feed it twice a year with a proprietary rose fertiliser, in spring and again immediately after the first flowering.
How should I prune a gaura?
Max Cline, by email
Stefan says: Gaura lindheimeri has long been one of my favourites and it was very popular with Victorian gardeners, too, with its delicate sprays of star-shaped flowers
and willow-like leaves. It’s fully hardy but I always leave the old growth over winter for added protection and cut it back close to soil level in March.
I have one last burst of garden colour from a solitary delphinium. Is this normal?
Sue Leedham, by email Stefan says: Nothing is normal in gardens any more! Thanks to our climate, which seems to have gone haywire, all manner of plants are doing things out of their ‘proper’ season. I’ve had roses repeat flowering several times and the lovely rudbeckias I grew from my Garden News seeds were still flowering well into November.