Five Great Houseplants for a Cool Sunroom
If you have a barely-heated sunroom, especially if there is a convenient water source there, you have an excellent opportunity to grow a variety of exciting indoor plants during the fall and winter. While plants such as African violets enjoy warm temperatures in the 60s and above, other pot plants require cool temperatures, in the 50s, in order to bloom and develop properly. Here are five types of indoor plants for this environment. The grower will need to go easy on the watering when it is gray and freezing out. A fan to move the air around and prevent stagnation will also help to keep the plants healthy, mold and fungus-free.
Standard and Miniature Cymbidium Orchids
Cymbidium orchids are as easy to grow inside as daylilies are outside. These large, strap-leaved orchids will produce multiple long-lasting sprays of flowers, typically during fall and winter. Two main types are sold: “mini” cymbidiums and standards. Minis are typically under 2 feet tall, standards sometimes 3 or 4 feet. And they can get several feet wide—not too small. Growing from new pseudobulbs each year, they need a summer outside in partial shade, preferably with a dose or two of blossom-booster fertilizer. What will cause most to spike are cooler night temperatures towards fall. Standards can lose potential spikes if temperatures at night exceed 55 for long. Some newer hybrids will still bloom in warmer temperatures. Each spike starts as a tight, light green pointed growth at the base of the pseudobulb that will gradually lengthen into a long stem of flowers. Certain cymbidiums have such long flower spikes that they may need staking, while other pendent types cascade downwards from a hanging basket.
Some cymbidiums will even tolerate a very light frost, although this is risky for the health of the plant. Orchids generally are grown from seed under sterile laboratory conditions, so home seed growing of cymbidiums is difficult. Mature plants can be divided to share with friends and fellow orchid lovers. Most available plants are mericlones, which are lab-propagated replicas of superior cultivars. Not only are their flowers of better quality, but the plants tend to be more vigorous and easier to grow. Many grow cymbidiums in fir bark, but they can also flourish in soilless mixes or even potting soil. Perfect drainage is essential.
Another famous cool grower is the camellia shrub. Their shiny evergreen leaves are dotted with large flowers in wonderful shapes. Singles, formal doubles, peony-flowered—there are many exciting alternatives. Colors include whites, pinks, reds, and even some yellows. A few are fragrant. Often grown in the garden south of US zone 7, they require cool nights to develop their buds. (Some have now been hybridized for outdoor growing in zone 6.) In fact, they should probably be left outside in the the fall if warm nights occur, to prevent bud drop. House temperatures are not generally good for them. It’s like bringing an apple tree in the living room—instead of heat, they need a dormant cool period. They should be watered before fertilizing, and prefer acidity and partial shade. Both overwatering and extreme drying should be avoided, since moderate moisture levels are preferable. Pruning before spring growth occurs will keep a potted plant shapely. Camellias can be propagated with cuttings and even their apple-like seeds.
Florist cyclamens are very satisfying plants that will hold their flowers for months in cool conditions. Growing from a large bulb just at the soil surface, they produce white, pink and red flowers and beautifully variegated leaves. Some miniature types are fragrant. As they are often offered for sale as houseplants, they are easy to find, but really prefer cool conditions to a well-heated house. When spring comes, they will look wan, droopy and tired. After giving them a dryish rest for a few months, they will spring to life again and produce new leaves before next winter’s flowering. Cyclamens can also be grown from seed successfully in a cool area.
The Herb Rosemary
Many herbs naturally experience dry, chilly conditions in the Mediterranean winters. Such semi-woody plants as rosemary, thyme, and lavender are happy there, and may also bloom in the cool, sunny conditions. In colors of blues, lavenders and white, their tiny flowers and leaves are charming details. Overwatering is the biggest enemy of these arid climate plants. Some growers put pebbles or sand around the base of their stems, to provide them with extra reflected light and good drainage at the stem area. Of course, growers can benefit from fresh herbs for cooking. Unlike many softer edible plants, such as lettuce, these aromatic herbs tend to repel insects and are not generally attacked.
Succulents and cacti often enjoy a bright, cool, dry winter. Infrequent watering is fine for these plants, and fertilizer can be reduced. By fall, the many Christmas cacti are ready to bud. Winter brings the kalanchoes. Towards spring, Easter cactus puts forth its starlike flowers. And by early summer, we anticipate epiphyllums such as the night-blooming cereus. They also like sandy soil mixes and pebble-topped pots. Surprisingly, many cacti are quite cold hardy, but require a chilly, dry rest in the winter.
Night Blooming Cereus Cactus
As spring approaches, many of these plants can scorch, so they may need a partially-shaded area. If you hold your hand over the plant and it casts a sharp-edged shadow, that is bright light. A soft shadow indicates more shade. Air movement from the fan will help to combat spring overheating. 6 hours of sun, preferably morning sun, is enough for most sun-loving plants, 4 or less for those that like more shade. Plant leaves may also feel hot to the touch if they are in danger of burning. Blinds, shade cloth or greenhouse paint can protect plants from excessive sun and heat. Insects, unfortunately, can attack some plants, so watch for these and treat them early if possible. Organic and less toxic sprays are preferred in a home. Insects can develop resistance to strong sprays quite quickly, just as microbes do to antibiotics, so strong chemicals can be self-defeating. Growers can mail-order beneficial insects such as ladybugs for fully enclosed spaces, which will work on the problem insects.
In the cool seasons, flowers are not lacking and the grower can anticipate an enjoyable procession of blooms throughout the year. A sweater (or two) for us, but flowers in the sunroom, by all means!