Miniature roses suffer seriously from drought, and will drop their buds and flowers after only a few days of hot, dry weather. Keep the soil constantly moist, and spray or mist the foliage once or twice a day. A mulch of pebbles, a mixture of half soil and half peat (peat alone packs down too heavily), or something similarly porous, will help keep the soil cool and moist.
Fertilizing
Light feedings of organic fertilizers such as bone meal or cow manure once a year, in early summer, are usually recommended. Or supply small amounts of a balanced garden fertilizer, or special rose food, in late spring and again in early July. A weak solution of liquid manure is also good and can be fed about twice as often.
Pruning and Training
In early spring, when new growth is first beginning to show on bush types, shorten all stems severely. I usually cut mine back to a uniform four inches. And of course, cut out cleanly any dead or mutilated branches. Make every cut just above a new shoot or leaf bud. Otherwise, pruning is limited to keeping the bushes shapely, removing faded flowers, and occasionally thinning the growth of old plants to admit air to the center.
Miniature climbers bloom on last year’s wood. They can be cut back to six inches when first planted, but are otherwise not pruned except to control ungainly canes or remove dead ones. Train the climbing canes into an attractive, open pattern as they grow, by tying them to the arch, fence, or other support they are to climb on.
Miniature tree roses can be cut back to a small but symmetrical head in spring and all dead wood should be removed. To keep them shapely, prune as needed during the growing season.
Insects and Disease
I protect my miniature roses, as I do the others, with an all-purpose rose spray or dust applied first when leaves begin to unfold, and repeated every week or ten days until the plants go dormant. Occasionally, during a long spell of hot, humid weather, I see signs that mildew threatens. If the all-purpose spray contains a fungicide (which most of them do), I use it immediately. If not, I may resort to dusting sulfur (which does mar the beauty of the flowers) or whatever sterilant is on hand.
Winter Protection