I replaced dozens of Old Garden Roses in a local public rose garden that had the same problem, live oaks shaded most of the rose beds in the perimeter of the garden. The garden was surrounded by hills planted with trees. To solve the problem of how to plant roses in partial shade I devised a sun and shade survey for roses.
The shaded area received c. 5 and 1/2 hours to 6 and 1/2 hours of full sun, in that area, and was in deep shade the rest of the time.
Sunlight is strongest between the hours of 8 am and 4 pm, so if you have full sun for 5 and 1/2 hours in that window of time, it will be stronger light than that cast before 8 a.m. and after 4. p.m..
For your latitude with 5 and 1/2 hours of full sun during the peak "rose window of time" I suggest doing the same thing that we did,The solution was to plant China and Old Garden Tea roses, and Noisettes, because all of these bloom normally with that amount of sunlight, in our latitude.
I checked every site where I wanted to plant a rosebush and evaluated the amount or absence of sunlight every two hours during one days time, at 8 a.m., 10 a.m. 12 noon, 2 p.m. and 4 p.m.. sometime during the peak months of the rose blooming season. Where I live that is between May and September, for modern roses and March through October for evergreen rose classes.
For the survey I poke a stick in the ground, everywhere I want to plant a rosebush, and on the map I label each stick A, B. or C, and so on.
If your hand will cast a clear shadow when held 3 feet above ground level: this counts as full sun.
-If the shadow cast is blurred, and you can tell there is a hand shadow cast on the ground, but cannot count the fingers in the shadow, this counts as partial sun.
-if your hand does not cast a shadow, this counts as total darkness as far as rosebushes are concerned.
I made a chart for each rosebush, and counted each hour of sun that was produced between 8 am and 4 pm.
2 hours of partial sun, counts as 1 hour of R.S.N., Rose Sunlight Hours.
So if I want to plant roses in a bed that has:
- partial sunlight, counts as 50% in time. and so if a bed has partial sunlight between 8 a.m. to 10 a.m. it counts as one hour total in Rose Sunlight Hours.
- full sun from 10am to 3 pm equals a total of 5 hours.
I know that China, Tea and Noisette rosebushes will bloom normally in that bed, (in our latitude or closer to the equator) because that bed receives a total of
6 Hours of "Rose Sunlight Hours".
where I live most large-flowered remontant roses, which include most Hybrid Teas and Hybrid Perpetuals, bloom best when they receive 8 hours of full sunlight a day.
I have found that for a rosebed that has partial shade or filtered shade, for the best re-bloom rosebushes from the 3 evergreen classes perform best;
China
Old Garden Tea
Noisette
. Although in our latitude, Hybrid Musk rosebushes are equally as shade tolerant as the evergreen rose classes,they bloom far less often; only 3 to 4 months a year, as they are not evergreen plants but have a long dormancy, even here near San Francisco, California I am especially fond of the Pemberton roses, Cornelia, Callisto, a good yellow that is very fragrant.
Polyantha roses are also tolerant of partial shade in our latitude; La Marne, Mlle. Cecille Brunner, Perle d'Or, The Fairy, White Pet' which I planted in a border are some of my favorites.
Wild roses are lovely in the outer areas that get a bit fewer than 5 hours of sunlight and a few wild roses will bloom slightly less than normal, but still give a good enough garden display with 4 and 1/2 hours of sun. Rosa moschata give good value with 3-4 months of bloom, and a bonus of luscious scent. Plus the foliage is attractive, R. moschata is slightly more shade tolerant than China, Tea and Noisette class roses. The single form wafts its' lovely fragrance further and more strongly than the double form.
For beauty and nearly constant bloom Old Garden Tea
My favorite shade tolerant roses include: Le Vesuve, Westside Road Cream Tea,
Lady Hillingdon, Monsieru Tillier, cl. Devoniensis, Archduc Charles, Mrs. B.R. Cant, White Maman Cochet, Gloire des Rosomanes, Cramoisi Superieur, and the climbing forms of any of the China and Tea ,classes.
the spray form of Cecille Brunner is as shade tolerant as the O.G. Teas and it produces more months of bloom than all the other forms of that rose, plus it has a lovely fragrance.
Grandmothers Hat is the only rose of its class that I would grow in partial sun, here it blooms normally with 6 and 1/2 hours of sunlight.
One of the most important things I feel I can share with you, is to start Old Garden Roses in a bed that is well amended and in FULL SUN, if at all possible.
I would wait until the bush is 3 to 4 feet tall before moving it into partial shade. This is especially needed if the plant is on its own roots and slow to build as some China and Tea roses are. ( a monthly liquid feeding of 12-12-12 will help China and Tea roses grow more quickly, after the soil is well amended. The taller the rosebush, the more sun it will accesss, and the more quickly it will bloom normally.
A light meter can show you clearly why growing them up in full sun is a good idea, the brightness of sunlight increases considerably even a foot above the ground level.
IF you do not have an area in full sun to grow the rosebushes to 3' to 4', then I would suggest you plant them in 8 gallon or larger pots, with rose soil and 1/3rd native soil, and submerge the pots so the rim is below ground level (otherwise the soil drys out more rapidly) where you plan to plant them, to see if the rosebush will bloom normally in an area with partial shade, it will be easy to pop up a pot and move it if it does not bloom normally there, without disturbing its roots.
Good luck and best wishes.
Luxrosa
p.s sorry this is so long, I mean to write an article some day and edit it better.
Q
Quartzite
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