The moss rose (Portulaca grandiflora), often called portulaca, is grown as an annual in most parts of the United States. Since they are ideal container plants, you can dig them up, plant them in containers and overwinter them indoors, provided you give them the appropriate care.
Overwintering Moss Rose
If your moss rose has thrived all summer long and you want to continue caring for it indoors in winter, dig up healthy plants that do not have pests. Do not wait until frost hits to dig up your moss roses, because frost will burn or kill the plants. Fill a plant container with commercial potting soil, not garden soil. A cactus soil blend works well. Use a container that will provide the portulaca with plenty of drainage. Fill the container with soil to about 2 inches below the lip of the container.
Video of the Day
You'll need to water the portulaca when the soil is dry. You don't want the plant to sit in a wet container, so discard water that collects in the saucer beneath the pot. When inside, keep the portulaca in a sunny spot, preferably a south-facing window. Make sure the room temperature is set at 60 degrees or warmer.
When potting portulacas from ground plantings, don't cram the plant into a space that is too small because this will encourage disease. Don't worry about fertilizing an indoor portulaca, however. You shouldn't need to fertilize the plant until spring, when it's best to set it outside.
More About Portulacas
If your goal in overwintering your portulaca is to encourage larger blooms, replanting overwintered portulacas may provide you with them. You may also want to overwinter your plants so that you have transplants ready for spring planting without having to purchase more of these annual plants. Portulacas, however, sometimes self-seed in places where they were planted as annuals the year before. This means that seedlings may sprout in spring in the garden bed where you grew portulaca the previous year.
Portulacas are annuals in U.S. Department of Agriculture zones 2 to 11, although they may survive winters in zones 10 and 11. Even when they die off after a frost, these fast-spreading plants drop seeds as they flower, and it's not uncommon for the seeds to sprout the following year.
If you decide to keep your portulacas in containers for the following summer, make sure the plants don't multiply in the container to the point of overcrowding. Overcrowded portulacas will produce taller plants with smaller flowers.
Portulaca Care Tips
Portulacas make ideal container plants. Because they spread, they can create a cascading look from hanging baskets and window boxes. If you are starting container plants from seed, make sure you do not keep the soil too wet. Use an organic slow-release fertilizer, preferably one meant for cactus You will also need to thin the seedlings to give the plants good air circulation.
When watering your potted portulaca, take care to water the roots and not the foliage, again keeping the soil moist but not overly wet. Foliage that remains wet provides the ideal breeding ground for fungal diseases that cause plants to rot. When you do fertilize, add an organic slow-release fertilizer. Too much fertilizer too quickly can cause root rot in portulacas.
While portulacas don't require deadheading, if you do remove the spent blooms, it will help the plant produce more flowers. Watch the plants closely for wilting or nutrition needs. When properly cared for, container portulacas will produce roselike single, semidouble and double flowers that are about an inch in diameter. Colors include white and pastel shades of rose, orange and yellow.