Q. What are some roses I could use on a roof garden?
The advantage of growing roses in a roof garden is that they get pleny of sun and good circulation around the plants. The disadvantage is that in some locations the sun can be too strong and, more serioulsy, they are exposed to damaging winds and extremes of weather.
If the location is very exposed then some kind of shelter, like a fence or a wall of evergreen shrubs, will be helpful. That said, there are lots of roses that can be grown in a roof garden.
Very large roses and most climbers are not suitable for roof gardens. Roses labeled "miniature," "patio rose/larger miniatures," "small shrub" or "medium shrub rose" are all good choices. The choice of roses in these categories is so large that it is difficult to recommend even a few. Perhaps the best plan is to go to a reliable nursery and choose the ones in these categories that appeal to you.
One specific recommendation that can be made, however, are roses in the Knock Out© family. These roses are disease resistant, drought and heat tolerant, long blooming and need little maintenance. A number of varieties ranging from red, to pink and even yellow are now available. It is also interesting to note that there are now miniature climbing roses available, e.g. Rosa 'Work of Art' 'Hi-Ho' and 'Little Girl".
Cultivation of roses in containers:
Probably the most important advice for growing roses is containers is to use a large pot. Pots of 15 inch diameter are good for larger roses and 12 inch for smaller species are suitable. Half barrels make good containers for roses. Include compost in the soil mixture to help water retention. As for all plants grown in containers or on roof tops or patios, regular watering is important. Also, roses are heavy feeders and should be fertilized frequently with a rose-speciific fertilizer.
These two web sites give good advice on growing roses in container and suggest suitable varieties;
This book has a useful chapter on "miniature roses":
L. Barnard (Ed.) 500 Popular Roses for American Gardeners. Barron's Educational Series, Inc., Hauppauge, NY (1999).
Another useful book is:
S. McCann. Miniature Roses. Their Care and Selection. Stackpole Books, Harrisburg, PA ((1991).
Courtesy of NYBG Plant Information Service