by BRIAN MINTER
August 29, 2000
The recent hot, dry spell has taken its toll on many of our annuals. Some varieties are starting to look somewhat hard, instead of being soft and vegetative. Stress is the major cause of this hardness and once experienced, many annuals stop growing and go to seed. Consequently, these stressed-out annuals can leave your garden looking a little blah at this time of year.
Late flowering summer perennials, however, can give your garden some needed colour. As I was walking through the gardens the other day, I couldn't help but notice how a few very special perennials were doing more than their share to keep the colour going.
I have praised astilbe many times, and I must again - it is such a tremendous perennial. I'll always remember the day the well known British garden author, Christopher Lloyd, came to visit. He let me know in no uncertain terms that he wouldn't have astilbe in his garden. He simply did not care for it. After seeing how we were using these wonderful plants at Minter Gardens, he rather brusquely stated that perhaps it wouldn't hurt to take a second look. Astilbe can carry your garden from June until September if you carefully select the varieties which bloom in sequence. Astilbes can be tall or short to suit most locations, however, they last best in partial shade. The new variety called 'Sprite' is supposed to be purple but surprisingly, looks like the old-fashioned 'Pumilia', which is just coming into bloom. Dwarf astilbes make excellent ground covers, and they are in their prime right now!
Yellow is always an important colour to give a lift to late summer gardens, and two excellent perennials immediately come to mind. The longest and strongest flowering variety has got to be the lacy leafed Coreopsis verticulata. I have a clump growing under adverse conditions in front of my office, and it just never quits. It always looks good without any care or attention and defies the concept of perennials needing a lot of work.
All coreopsis varieties are fairly good for colour from July to October, but Coreopsis verticillata grandiflora and the compact form, 'Zagreb', have been the most outstanding. A new variety, coming from one of Britain's top breeders, is called C. 'Flying Saucer'. These huge, single, yellow cupped flowers have serrated edges and with a little breeze, they're true to their name, swirling like little flying saucers.
My other favourite yellow perennial is a rudbeckia called 'Goldsturm'. This European introduction is just out of this world! It's hardy, relatively short (about 24 inches tall) and its large, single, yellow daisy-like flowers just keep on blooming right up until November. 'Goldsturm' is such an improvement over the other varieties - they're not even in the same league! A new compact rudbeckia from Blooms of Bressingham, called 'Viet's Little Suzy', has smaller flowers but lots of potential.
Daylilies are certainly making a comeback, and with the tremendous breeding being done, some spectacular colours are coming out. Looking through new daylily catalogues, it's hard not to drool on the pages. The new colours are a match for many orchids. What really interests me for their continuous flowering and attractive low growing habit are some of the new dwarf strains, like 'Stella d'Oro'. 'Happy Returns' is a new yellow variety that looks just like daffodils in summer!
One of the more unique late summer perennials is Chelone obliqua, more fondly known as 'Turtlehead'. Each flower pokes its nose out of its shell just like a turtle. A strong, longlasting bloomer, it takes summer heat in its stride, and the white or pink blossoms always look fresh and exciting.
Some other excellent late summer blooming perennials not to be forgotten are the pink-lavender blooms of Joe-pye Weed (Eupatorium ‘Atropurpureum); the rich golden yellow, bronze and reds of dwarf heleniums; the white, fragrant flowers of all the cimicifuga; and some of the new heliopsis varieties that make wonderful backdrops for perennial borders.
In spite of the weather we may experience from year to year and how it impacts on our annuals, these perennials, and many more like them, are the work horses of any garden and will ali wonderful colour to a late summer garden.