OUTDOOR PLANTING AND CARE
In all except mild or warmer climates, bare-root plants bought by mail from nurseries or garden-rose specialists should be planted in early spring, when vigorous root action and growth are beginning. Potted plants or any that come complete with a soil ball around the roots can be planted almost any time the garden soil is not frozen. But in sections where winters are severe, I think spring planting is always safest. In fact, in Connecticut I like to give new plants a longer growing season their first year by starting them a few weeks early, in pots, indoors or in the greenhouse.
Location
Plant miniature roses where they will get at least half a day of summer sun (a full day is best) but where it is possible to keep the soil suitably moist. Avoid low, muggy pockets where air does not circulate freely or where water can collect and make the soil muddy. Good drainage is vital. In cold areas, select a spot sheltered from icy winds by a wall or low shrubs.
Soil
To help keep them dwarf, miniature roses need a fairly heavy soil, but not, of course, too clay-like. Dig down at least ten inches, to prepare for the deep-growing roots, and improve the soil you remove with whatever is needed before you replace it around the plant. Clay-type soils will need the addition of sand, for drainage, and leaf mold needs rotted or dry cow manure or other humus to lighten the texture. Sandy soils need humus to help hold moisture. In even average fertile soil, miniatures appreciate an extra ration of humus at planting time.
The ideal soil for miniature roses will pack firmly around the roots, yet won’t cake and crack in the sun. It drains perfectly, so excess water does not stand around the roots, particularly in winter. Yet it holds enough moisture so that the roots don’t dry out so fast you can’t keep up with the watering job. Soil should also test neutral or slightly acid (pH 6.0), never extremely acid. In acid-soil areas, apply a light sprinkling of horticultural lime each winter.
Planting
Plant miniature roses about a half-inch deeper than they were before, and far enough apart so that they will have room to spread as wide as they will be tall. Crowded plants have no individual beauty, but they are prime targets for mildew. If the weather turns sharply cold or dry and windy after planting, protect the plants by mounding up soil around the stems. Remove it gradually as spring days grow balmier.
Watering