By Mike Chute
Could that have been a rose leaping out of a five-gallon pot in my garden late last spring? Yes, it was ‘Neptune’, a new hybrid tea from Weeks Roses. I acquired this rose with large lavender blooms, strong fragrance and shiny leathery foliage at the Yankee District auction last March. Rather than plant it directly into my garden, I potted it up with twenty or so other roses that made up this season’s roster of prospective “super roses.”
I define super roses as roses that are successfully forced to their maximum potential. I plant them in containers and that allows me to control most of the factors that make them grow. This includes the best potting soil, a gourmet diet, copious amounts of water, adequate sunshine, and complete insect and disease control. Add in a discerning rose gardener, cooperation from Mother Nature, and a little serendipitous good luck and the results are an array of stunning rose bushes. Since all this takes place outside in my garden without benefit of a greenhouse, the process is subjected to the vagaries of nature. Late frosts, not enough warm weather, too much warm weather, and windy days are some of the hazards beyond my control. The horticultural challenge is to grow the strongest, healthiest, and most floriferous roses possible, in effect, creating a class of super roses.
I began growing roses in containers seriously six years ago when I took a few bare-root roses and potted them up into handy plastic containers in the early spring of that year. The results were pretty good and I enjoyed the process so much that I repeated it the following year with a few more roses.
Each year as I became more scientific, the results got better and the containerized roses began to out-perform the garden plants. Container rose gardening gives me far more control of the plants’ environment and the flexibility of positioning them for optimum growth. Growing roses successfully in containers is not complicated and requires the same rose-care basics as do in-ground roses. There are, however, extra details to take into consideration:
Plants: Start with the best possible plants…the variety is not critical. I get excellent results with fresh, two-year-old, number one, field grown bareroot roses. Some previously potted roses will work but require more attention in the early spring after recovering from the cold weather months spent outside under winter cover. Avoid small, substandard roses regardless of cheap price. They will never be super roses.
Soiless mix: The best potting soil is no soil at all. I like Pro-Mix BX, a soiless mix, which comes in 3.8 cubic foot bales and can be found in many garden centers. (The cost is around $20 per bale and one bale will fill 10 five-gallon pots.) ProMix is a peat-based professional growing mix consisting primarily of Canadian sphagnum peat moss with perlite and vermiculite, along with dolomitic and calcitic limestone as pH adjustors. It is lightweight, uniform, free of insects, insect eggs, and diseases plus it holds plenty of water. It is ideal for plants in the 5 to 7 pH range…perfect for roses.
Potting: Potting is completed by April first. I prune the canes as I normally do, but trim the roots a little more aggressively for a good fit in the pot. I use new five-gallon plastic pots because they are large enough to support healthy roses for one season and small enough to move around the garden. After one season, the plants may be root bound and should be planted in the ground or repotted into a larger container. It is not necessary to plant the bud union below the soil surface as the rose should be replanted in the ground by season’s end. If not, then mulch heavily in the fall.
After potting, I place them side-by-side on heavy benches erected along one side of my garden and move them further apart as they spread their wings. As the weather warms and the rose growth accelerates, I turn the pots every few days for even sun exposure.
Feeding: Nutrients must first be in solution before plants can absorb them. When the soil has warmed sufficiently to stimulate new growth, usually by late April, I commence feeding by using water-soluble fertilizers exclusively . . . any brand will do: Peters, Miracle-Grow, or Magnum Grow (now known as Magnum Rose). I particularly like Magnum Rose because it has all the necessary macronutrients - nitrogen, phosphorus, and potassium (N-P-K) - as well as chelated micronutrients. It also contains magnesium sulfate (epsom salts) and a soil penetrant thus providing an all-in-one water-soluble concentrate. I am constantly experimenting with plant nutrition and always willing to try new products. I use fish emulsions and seaweed extracts plus plant tonics like Jump Start, a mixture of growth regulators, vitamins, and organic ingredients known to be beneficial to growing roses. These supplements work when used in modest amounts. Since water-soluble fertilizers are already in solution, they wash directly into the root zone initiating the immediate uptake of important nutrients. I cut the recommended dosages in quarters and apply weekly. You can find me on any Sunday evening stirring up a tasty nutrient cocktail in a blue five-gallon pail like an old moonshiner. I ladle out a precise amount into each pot. This explains in large measure why these containerized roses out-perform garden plants in the short term.
Insect and disease control: I apply insect and disease controls every ten to fourteen days on the same schedule as the garden.
It takes about ten weeks for large roses in pots to bloom in the spring. If potted by April first, then the first flush will be in mid June without any help from me. I can speed up or retard blooming, to a degree, by moving the pots in and out of the shade. Although every variety has its own built-in genetic time clock, generally speaking, roses with fewer petals will bloom sooner than heavier petaled blooms. The weather becomes the wild card with heat and light accelerating the timetable. For instance, the roses in the Victorian Rose Garden in Roger Williams Park eight miles away in Providence with uninterrupted dawn-to-dusk sunlight will bloom 8-10 days sooner than those in my cool, shady garden. Limited sunlight is the major drawback in my garden. I trimmed away perimeter vegetation last winter around the garden to create corridors of sunlight and placed the benches in those corridors.
I select plants that have attractive, eye-catching blooms, outstanding foliage and symmetrical habits and then supersize them. While the program begins in April, the most noticeable improvement in the plants doesn’t occur until mid-May when the air and soil temperatures become consistently warm. The roses respond to this high intensity horticulture with robust new growth and showy displays of color, but occasionally I get an unexpected outcome. For instance, this year I potted up ‘Scarlet Meideland’, a landscape rose with a sprawling, procumbent habit. I envisioned thousands of tiny, shiny leaves and great clusters of fiery red blooms cascading nicely out of a terra cotta pot. Instead I got a burly maverick that shot out heavy canes like roman candles every which way…a little too robust for a container. On the other hand, ‘Passionate Kisses’ matured slowly and steadily into a fabulous specimen by late June. This floribunda developed perfect symmetry with sprays of luminescent salmon pink and immaculate foliage. The blooms had incredible substance allowing them to hold for a week on the bush. I even entered it in a container class in the Newport Flower Show in late June. But most varieties are predictable and I eventually plant varieties that I like in the garden, especially if they are decorative shrub roses. The rest I sell.
There are many ways to enjoy rose gardening. For me, it is the pure horticulture of raising roses to be the best plants possible by providing each plant with all the essentials that it needs. Whether it is enjoying ‘Neptune’ leaping to the heavens or ‘Passionate Kisses’ quietly developing into an all star, each one is a super success in its own way.
Editor’s Note ‘Passionate Kisses’ won Best of Show in the Horticulture Division at the Newport Flower Show.
Rhode Island Rose Review August 2004
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