Miniature roses are dwarf versions of roses including the classic hybrid teas. Though they are much smaller (12 to 15 inches tall or less), they are surprisingly tough and can be planted outside where they will survive our Kansas winters if mulched. However, many gardeners like to grow the miniatures indoors where they can enjoy them during the drab winter months.
Miniature roses grown as houseplants have specific requirements. For long-lasting flowers, air should be moist with a relative humidity of 50 to 60 percent preferred though 40 percent is adequate. Placing the pots on a tray that holds moist pebbles will help provide the humidity needed.
Like most plants, roses need a lot of light to flower. Though miniature roses will survive in a south window, many people will supplement available light with fluorescent lamps. Timers can be used to automatically turn the lights on and off. Providing 14 hours of light per day will be plenty for roses to grow and flower. Lights are normally spaced 3 to 4 inches above the tops of the plants.
The most serious pest of these plants indoors is spider mites. These mites are very small but can devastate miniature roses. They like dry, warm conditions. Maintaining adequate relative humidity levels and washing the plants once a week in tepid water will help prevent problems. If mites do develop, try using an insecticidal soap or horticultural oil (2 percent rate) for control. The horticultural oil will be more effective than the soap. Be sure to spray or wash the entire plant including the underside of the leaves so that all mites are contacted.
Miniature roses can be placed outdoors during the summer to take advantage of higher light levels. Do not place the plant in the full sun immediately but gradually grant less light over a period of several weeks. Pots sunk in the ground will not need to be watered as often as those exposed. Turn the pot 180 degrees every couple of weeks to break off any roots that escape the pot and move into the underlying soil.
Miniature roses are not the easiest plants to grow as houseplants but can be well worth the effort required.
Lauren Fick is a Cottonwood Extension District Horticulture Agent. Hays Office: 785-628-9430. Great Bend Office: 620-793-1910.