Flowering plants make excellent houseplants in Minnesota, bringing their brightly colored and frequently fragrant blossoms indoors during a time when all of the outdoors is frozen. Many of these tropical flowering plants prefer relatively cool indoor temperatures, which are easy to provide during cold Minnesota winters. Put them in a brightly lit spot and move them outdoors during frost-free summer weather.
A perennial in its native tropical areas, hibiscus (Hibiscus rosa-sinensis) is widely grown as a potted indoor plant in Minnesota and moved outdoors during frost-free weather. The exotic-looking flowers come in shades of red, pink, magenta, coral, cream and bicolors. Grow them in a warm, bright, sunny location with daytime temperatures between 65 and 75 degrees Fahrenheit. Temperatures below 55 F cause hibiscus to drop its buds before they open. Keep away from artificial heat sources and doors to the outside; hibiscuses are sensitive to drafts. A south- or west-facing window is ideal. Water to keep the soil moist but not overly wet. During winter, the top of the soil should be dry to the touch before watering, but do not allow it to dry out any further. Fertilize monthly in summer and every six to eight weeks in winter using water soluble fertilizer mixed to half the manufacturer's recommended strength. Prune in early spring to remove spindly growth and to maintain the plant's desired shape. Hibiscuses withstand pruning well and can be hard-pruned with little adverse effects.
Popular as gift plants, cyclamen (Cyclamen persicum) is a native of the Mediterranean that is dormant during hot summer months and in active growth in the cool fall and winter months. Kept in a cool, brightly lit room, they make excellent houseplants in Minnesota. If possible, move them directly in front of a window or another extra cool location at night because they prefer nighttime temperatures of 50 F or below. Grow them at cool room temperatures of about 68 F during the day. Let the surface of the soil dry out before watering thoroughly. Do not apply water to the center of the plant or the tuber may begin to rot. Pour off any accumulated water in the drip tray and do not allow the pots to sit in water. Remove dead flowers when their stems separate from the plant if given a gentle tug, but don't force it or you may remove some of the roots along with the spent flower stem.
One of the most common citrus grown indoors, calmondin orange (Citrofortunella mitis) produces small sour fruits that can be used to make orange marmalade or for garnishes. Position your orange in bright, direct sun at temperatures of 65 to 68 F during the day and about 5 degrees cooler at night. Grow them in slightly acidic soil, using a mixture of one-third potting soil, one-third perlite and one-third peat moss. The peat moss will help reduce the pH of the soil and make it slightly more acidic. Feed your orange with a fertilizer specially formulated for acid-loving plants mixed at half the manufacturer's recommended strength from April through September. Withhold fertilizer during the tree's slower growing period during the winter months. Inspect the tree regularly for scale, whitefly and spider mites. Spray with horticultural oil if any of these pests are detected, following the manufacturer's instructions carefully. Move your orange tree outdoors during frost-free weather, from mid to late May through September.