We’re close to Boulder Valley’s “average last frost” date, and except for being windy and dry, it sure feels like Spring! Lots of gardeners are asking whether it’s safe to prune now, especially roses and shrubs. The answer is YES! But…..
Pay attention to the characteristics of the particular shrubs and roses you’re thinking of pruning. If the shrubs in question won’t be in bloom until summer or fall (for example: Blue Mist Spirea, Rose of Sharon, Russian Sage, Rabbit Brush, Seven Sons, Butterfly Bush, ‘Mongolian Gold’ Bush Clematis), now is a great time to prune them for compact form, removal of winter-kill and dead tips. These shrubs bloom on new (this year’s) wood, so you won’t be diminishing their bloom potential by pruning now.
These are native plants that we often have for sale. Availability does change every year, but we grow and buy a wide variety of natives because they are so successful in our gardens.
KEY: t = tree, s = shrub, v = vine, gr = grass, gc = ground cover, p = perennial,
b = biennial, a = annual
Abronia fragrans (Sand Verbena) (p)
Acer glabrum (Rocky Mt. Maple) (t)
Acer grandidentatum (Bigtooth Maple) (t)
Achillea lanulosa (Native White Yarrow) (p)
Agastache cana (Hummingbird Mint) (p)
Agave parryi (Hardy Century Plant) (s)
Achillea lanulosa (Achillea millefolium var. lanulosa) (Yarrow)
Agave havardii (Havard’s Century Plant)
Agave parryi neomexicana (New Mexico Century Plant)
Amelanchier alnifolia (Serviceberry)
Amorpha canescens (Leadplant)
Amorpha fruticosa (False Indigo)
Thank you for buying your roses at Harlequin’s Gardens nursery! To get off to a good start for growing beautiful, healthy roses, please follow these planting instructions. Please read them through before you begin.
WHEN: Many of our roses have been over-wintered outdoors; these may be planted as soon as your soil can be properly dug and worked. Otherwise, in Colorado’s Front Range region, plant roses after the average “last frost” date (in Boulder, May 15). Roses that have just arrived from greenhouse growers will need to be “hardened off” for 4 to 7 days prior to planting. Keep them outdoors in a place where they’ll be somewhat protected from sun, wind and major temperature changes (you can bring them into a garage or shed temporarily to wait out a late frost or storm). You can plant roses all through the summer, as long as you can keep them watered. And we’ve had great success with fall planting, well into October, with monthly winter watering.
- “Banshee” (found) Z 4, dbl pink 2″ early & long-blooming May-June, rich sweet damask fragrance; large shrub or climber, no die-back, very disease resistant, very tough & tolerant of low water, poor soil, shade, once established. Distinctive matte foliage, fall color- purple, orange. Common in old neighborhoods all along the Front Range.Not terribly prickly. Cut armloads for big fragrant spring bouquets!
- “Broadway Perpetual” (found, Boulder) Z 5 (4?) Large dbl strong pink quartered, deep old-rose perfume, spring & fall, sporadic in between. Good cut-flower. Seems somewhat shade-tolerant. Strong arching growth to 7’. Potential climber? Healthy foliage, moderately prickly.
- “Fairmount Proserpine” (found, Denver)
Here is the basic approach which we use at Harlequin’s Gardens to grow hundreds of roses without using any pesticides or fungicides, and only using a few soft controls.
I know of one lilac that has some repeat flowering in the fall, but I’m not aware of any spireas, mockoranges, shrub honeysuckles, forsythias, serviceberries, butterfly bushes, rabbitbrushes, cotoneasters, or other shrubs that repeat their flowering cycle. Why is it, then, that many gardeners demand continuous flowering roses ? We want them, of course, because they exist.
The fixation on constant flowering is encouraged with annuals, which, of course, don’t really start blooming until late spring or summer and then the first winter, they die. And seasoned gardeners know that the search for perennials that “bloom all season” leads to the proper selection of many species that will bloom in succession. So when we hear of roses that bloom from May or June through September, we think we have found the holy grail. However there are qualities besides repeat flowering which could entice us to cultivate the so-called “once-blooming” roses. I would like to share these not-so-obvious reasons with you.
Roses are certainly one of the world’s most beloved flowers, and yet many people have given up on them because they have gotten the reputation of needing frequent spraying, feeding and fussing. They got this reputation because for decades, hybrid tea and floribunda roses were bred mostly for special colors, a particular flower form and repeat flowering. Their value was judged more for the exhibition table than for the garden. Now, as more people have become aware of the dangers of pesticides and as the trend has moved to “care-free” shrub roses for the garden, rose breeding has shifted in the last ten years towards more sustainability.
Many gardeners think of Spring as the height of the ornamental gardening
season. Sure, so many of our best-known flowering plants – Tulip,
Crocus, Daffodil, Primrose, Peony, Lilac, Forsythia, Oriental Poppy,
Basket of Gold, Bearded Iris, are at their showiest in spring. But as we
pass to the other side of the Summer Solstice, a whole new palette of
blooms arises, including many Natives, lots of Prairie-dwellers and
Steppe plants, and hardy plants from South of the Border, bringing bold
color and attracting more and different beneficial insects and
pollinators to the garden. Here’s a list of many of those flowers to
The Canadians, like their English and French ancestors, have a great love of roses. However much of Canada is in zones 4, 3 and even zone 2. Therefore many of the hybrid tea and floribunda roses bred in modern times have not been tough enough for Canadian gardeners. So the Canadians set their own federal agriculture department to work on breeding roses that succeed in Canada. Not only do these roses do well north of our border, they are very successful in Colorado, even in our higher elevation environments. Our 10-20 below zero winters and dramatic temperature changes can kill or significantly injure more tender roses like the hybrid teas and floribundas. So gardeners in Colorado who don’t have time to remove large masses of dead canes, hill soil around the canes to protect them for winter, and who have less inclination to spray and fertilize frequently, find the Canadian-bred roses provide a rewarding and easy-care alternative.
Many Colorado gardeners have been frustrated in their attempts to grow climbing roses. The main problem seems to be that the tall canes die back and though they may bloom, they look like shrubs, not climbers. We are green with envy of the European and Californian gardens with roses cascading over and festooning pillars, walls and bowers. Why can’t we achieve this? I think we can, but not without a very discriminating approach. First of all we must realize that our cold temperatures and especially the rapid cold-hot-cold changes, and our drying winter winds are death to all but the hardiest rose canes.
Henry Kelsey (1984 Kordesii cross) is an Explorer Series rose from Ag. Canada that is hardy to Zone 3 and is considered by many to be the best red-flowered climber for cold climates. It is very vigorous and grows strongly even in lean soils. Whereas it can be grown as a low arching shrub to 4’, it excels as a short climber to 8’-10’ and looks especially good trained down a split-rail fence. The flowers are semi-double with prominent golden stamens, opening a luscious deep red and fading to a pinker medium red. The fragrance is light but pleasant and the clusters of flowers repeat from June until frost. Where I have grown it in a very low water area over the last five years it has performed well and has not died back on the trellis, but repeat flowering is intermittent rather than continuous. One of the truths of xeriscape is that not all plants that grow well on low water, flower as well. Sometimes just one or two deep waterings during bloom time will make a big difference in flower production.
At the end of last season I wrote about how to succeed with climbing roses in Colorado. Besides winter watering and careful siting out of the worst wind, the most important factor is the choice of very cold hardy roses that are grown on their own roots. The books may say we are zone 5 but when the temperature drops from 50 at noon to 5 at two a.m., we better hope our rose is zone 4 or even zone 3 hardy. With climbers this is even more true because if the canes die back to two feet the rose may still bloom but it won’t function as a climber that year. Here are a few of the toughest and most cold-hardy climbing roses for Colorado.
After last November’s 77 degree cold plunge to 13 degrees below zero, most roses suffered die-back, some died to the ground and some died completely. But there were roses that had only minimal damage and some that will bounce back with a good show of vigorous growth and generous flowering this year. Here are some observations and conclusions about growing sustainable roses in Colorado.
Roses are cane shrubs, similar to blackberries and raspberries. Their wood has a pithy center and is not as hard or as strong as a lilac. Consequently roses are more vulnerable to insects, diseases, desiccation and cold, but another consequence is that they can grow and regrow much faster than woody shrubs like lilac and viburnum.
Plants are one of the most successful life forms. In fact, we could say that they are the most successful life form, because plants are self-sufficient. They can live without eating other beings because they can make their own food. Only plants, phytoplankton, algae and cyanobacteria can synthesize food from sunlight, carbon dioxide, minerals and water.
At the same time, plants have a serious limitation: they are rooted to the earth, so they can’t run away from pests and they can’t pursue another plant in order to have sex. But are plants helpless. Oh, no. They have developed chemical warfare and chemical magnetism to protect themselves from predators and attract allies.