Healthy roses in bloom

The roses are looking healthy and so far I don’t see any sign of the dreaded black spots that often plague the foliage of these shrubs. This may be because I select rose cultivars known to be resistant to blackspot disease and then integrate them with other perennials and shrubs. Growing many roses together in a traditional rose bed sets up a monoculture that invites disease—if one gets sick, there’s good opportunity for the pathogen to spread quickly to vulnerable neighbours.

I have some dreamy roses this summer! ‘Etna’, a purple-red moss rose (named for the Sicilian volcano), and tall, bright pink ‘Therese Bugnet’ (a hybrid of Rosa rugosa and R. blanda, bred in Alberta) with raspberry canes. Both have a deep, fruity perfume and strong resistance to blackspot. The climbers are doing well, too. ‘Blossomtime’, a pink rose with darker reverse petal, is growing through a Viburnum carlessii and ‘Clair Matin’, with frilled light pink petals and bright yellow stamens, is growing up and into a ginkgo tree. I like to use taller woody plants as supports for climbers; it’s a natural look and easier than tying them to a trellis.

It’s time to feed the roses again in order to stimulate new wood for more flowers through the summer and early autumn. This can be done any time during the month of July, but feeding roses in August runs the risk of spurring tender growth that won’t mature before frost. Their first feeding was in May when I gave them a water-soluble fertilizer, but I was uncertain about how much might have leached away with the excessive rain we had. Roses are eager eaters, requiring nutrient supplements to produce the numbers of blooms gardeners desire.

When I looked through the garage I found various suitable products still in fresh condition—a generous amount of alfalfa pellets, two bags of composted cow manure, half a bag of worm castings, two boxes of bonemeal and a bag of kelp meal. These are all organic materials with low nutrient analysis. My plan is to combine the cow and worm manures as the main fertilizer; they’re low in basic nutrients and won’t burn plant roots, and rich in beneficial enzymes and bacteria. I’ll mix in some alfalfa pellets for a gentle amount of nitrogen and, more importantly, for the naturally occurring hormone triacontanol (an alcohol ester compound that acts as a growth stimulant) it contains. I’ll add the bonemeal for a supply of slow-release phosphorus, and the kelp meal for potassium and plant hormones.

This may seem a cavalier method of combining nutrients without carefully measuring or considering the specific nutrient analysis, but that’s one of the benefits of working with simple organic materials. I’ll provide three or four trowels of the mix to each rose, scratching it into the soil over the roots, and not worry about overdosing plants with high amounts of nutrients. The added benefit is the full range of trace elements available in these materials, and the biological enzymes that activate soil organisms. Roses respond enthusiastically to organic foods. They’re going to love this!

Return of the Japanese beetles

With roses in full bloom, can Japanese beetles be far behind? I haven’t seen one in my Toronto garden yet, but Garden Making editor Beckie Fox found them last week in Niagara-on-the-Lake on her ‘Mrs. John Laing’ hybrid perpetual rose. This is a gorgeous pink rose, fully double and with quartered petals, and beetles crawling around in all those tightly packed flowers would be, well, really creepy. [Ed. note: Disheartening, too.]

In past years, my own roses were devastated by the beetles and I had to remove some lovely shrubs, simply because the beetles were so efficient at destroying the newly opened flowers, almost overnight. It’s hard to find a quick remedy for the problem. Skunks and raccoons dig the grub stage of the beetles, causing a different kind of carnage in the lawn, and I suppose that must reduce their numbers a little. I did consider setting up a couple of pheromone beetle traps, which attract them with sex hormones and trap them in a bag. But my fear is that the sexual lure would make my garden a red light district, drawing far more beetles than I might normally have.

My two climbing roses (‘Clair Matin’ and ‘Blossomtime’) continue blooming through the summer and are definitely delicious hosts to Japanese beetles. I found a sort of solution by planting early summer-blooming roses (‘Canary Bird’ and ‘Etna’) that finish flowering just as the beetles make an appearance. Then for the rest of the season I rely on Knock Out roses (40 x 40 in. / 1 x 1 m, Zone 6) that bloom consistently all summer until frost. There are several cultivars in the Knock Out group, with bright colours (red, light and dark pink, and yellow) in single and double flower forms. They’re disease resistant and self-cleaning (no need for deadheading) and bloom in clusters, providing lots of petal colour. These roses don’t have any perceivable scent, and I think that’s the key to their success in my garden. The beetles are attracted to scented roses, and I’ve never found a beetle on a Knock Out rose. Hardiness is a problem, as they’re at the edge of their cold resistance in Zone 6, but they’re vigorous growers, and any winter damage is quickly replaced. In colder zones, it’s feasible to plant Knock Out roses in containers and move them into an unheated garage for the winter. That should keep you “in the pink” and one step ahead of Japanese beetles.