Most alliums will spread nicely; they even look good once they are out of bloomMarjorie Harris
Why you should plant it
This is a paean to all types of allium. Those illustrated (A. 'Purple Sensation' and a white A. 'Cowanii') show how well they fit into any border with any plants. They refresh any tired edge, look sprightly and can be tucked in easily around other plants. Most alliums will spread nicely; they even look good once they are out of bloom. I leave mine to brown out, but I know people who spray-paint theirs brilliant colours. They are perennials, so choose and plant carefully.
Where to plant it
All alliums need well-drained soil in the sun. Dig a largish hole that is at least three times the thickest part of the bulb deep. Deposit the bulb and water the hole deeply, then tamp down the soil and water again. Make it look like it's undisturbed soil and the squirrels, which don't like these bulbs but will dig them up anyway, won't touch them. Cover with leaves, mulch and wait for spring.
What it offers
There are so many good ones: Allium 'Millenium' blooms all through August to the end of September and it makes a great container plant, but it's very new and hard to get. I'm going to plant dozens more this year, especially the A. atropurpureum, which has an almost black-purple vase-like umbel (flower) and 90-centimetre stems that make a great bouquet if you plant them by the half-dozen close to each other. A. roseum, meanwhile, has 50-centimetre stems, makes lovely clumps and will spread around. The spectacular ones are A. 'Christophii' (which looks like a bright pink flash of stars) and A. bulgaricum (which boasts blue-green and purple umbels and creates a mysterious shadow against other autumn plants).
Source and cost
Prices vary from $1 each up to $12 each. You'll find a good selection at most high-quality nurseries. Don't try to find bargains. You get what you pay for and big, lush bulbs are what to look for. I get mine at Toronto's Fiesta Gardens (www.fiestafarms.ca); www.gardenimport.com also has a wonderful collection. – Marjorie Harris
For more plant and garden info, visit www.marjorieharris.com.
Q&A
I have suddenly discovered a Rose of Sharon (Hibiscus syriacus) in my garden and it's seeding everywhere. What should I do?"
It probably hasn't been all that sudden. Rose of Sharon is so invasive that you may have got it from someone down the street. With this plant, every bloom falls off after one day and leaves behind a seed pod that contains dozens of seeds, every one of which will germinate if they fall on even the worst soil. Put them near decent soil and you'll have a farm. They are also light enough to be blown about on the wind. You may spend the rest of your life pulling out seedlings and so will all your neighbours. Alternatively, you could just get rid of it. The reason that most people plant it is their belief that nothing else blooms at this time of year. Of course that's not true (see above). Other great autumn-blooming trees and shrubs include Heptacodium, Hydrangea 'Fire and Ice' (and dozens of other fantastic hydrangeas) and Syringa 'Bloomerang,' the re-blooming lilac.