Don’t let the delicate appearance fool you! These little gems are hardy enough to grow outdoors in zones 6-10 without winter protection, and with a good cover of mulch they will survive winters as far north as zone 4. Miniature roses are surprisingly easy to grow, and they look great as edgings for your beds or borders, accent plants for rock gardens, and as houseplants.
Miniature roses range in size from the micro-minis which grow to about five inches, up to a height four feet or more. The flowers are from 1/2 inch to two inches in diameter, and the range of colors is similar to that of full-sized roses. Most types will bloom from spring until frost. Unfortunately, miniature roses have little or no fragrance.
When grown indoors as pot plants, miniature roses need a little special care. Even when grown in the sunniest window, they will usually need supplemental light. You will know your rose isn’t getting enough light when the stems seem to stretch out leaving wide spaces between the leaves.
Miniature roses also need lots of humidity if kept indoors. Set your pot in a tray of pebbles and water. The pebbles will support the pot above the water level so the soil doesn’t become waterlogged. As it evaporates, the water will provide the plant with extra humidity. If you house is very dry, run a cool-mist vaporizer now and then.
Spider mites and whiteflies are drawn to indoor miniature roses. To reduce the chances of these pests attacking your plants, give them a weekly shower. Take care to thoroughly rinse both the tops and the undersides of the leaves. To treat whiteflies, use an insecticidal soap at five day intervals or spray with a solution of four parts water to three parts rubbing alcohol — add a squirt of dish soap for good measure — and keep the plant out of the light until the alcohol dries completely.
Soap spray and alcohol spray also work for spider mites, and you might also try buttermilk spray: mix 1/2 cup buttermilk with 4 cups wheat flour to 5 gallons of water. Quarantine infested plants until you are sure that the insects are irradiated. In extreme cases, you can strip the leaves off the plant and cut it back by half. Don’t worry, you won’t kill it, and you’ll soon see signs of new growth.
For the best blooms, use a fertilizer that is high in potassium. The last number in the N-P-K ratio indicates the amount of potassium, and an N-P-K ratio of 5-5-10 is a good choice. Mix the fertilizer to about 1/4 strength and use it once a week.
After your roses spend a season indoors, it’s best to plant them outdoors and get new, disease and pest-free plants to use indoors. They can be planted directly in the garden or kept in containers, but remember that outdoor plants in small containers can dry out quickly. Harden them off before placing them outdoors permanently.