Issue: January 15, 2000

Can I plant poinsettia and Christmas cacti outside?

I have a poinsettia and Christmas Cactus. Do I leave them in the pot, transplant them into another pot, or plant them outdoors? Are they plants that grow all year round and only bloom in the Christmas season?

Both the Christmas cactus and the poinsettia are not hardy outdoors and will freeze if planted outside. They should remain in their pots and not be planted outdoors in the garden if you live where it freezes in the winter. Repotting is a good idea for the poinsettia especially.

Poinsettias can become rather large and need a large pot. Christmas cacti should be repotted when they become large. The Christmas cactus will tolerate a small pot better than the poinsettia.

Following flowering, the poinsettia may drop its leaves and become dormant if it is too cool or if other environmental factors cause stress. If it is too dry, it will drop its leaves. If the humidity is too low, it may drop its leaves. If it is in a room that doesn't receive enough light, it may drop its leaves. By lowering the temperature of the room and reducing water, it will enter a period of dormancy. This makes it easier to maintain until growth resumes in the spring. Once it begins growing, resume watering on a regular schedule and raise the temperature of the room in which it is growing. Once the chance of freezing has passed, it may be placed outside in well-lighted location in the garden. Full sunlight may be too much for it in New Mexico, but it needs a well-lighted location. Grow it in its pot outdoors until it is necessary to bring it indoors to prevent freezing in the autumn. The Christmas cactus has no leaves to drop. The plant consists of flattened stems that look like leaves. This plant is dormant in the fall before flowering and will be ready to resume growth soon after flowering. During the fall, reduced watering (not eliminated) and cool temperatures favor the development of flowers during the long nights of autumn and winter. While it is flowering, don't overwater, but it will need some watering. Following flowering, growth will resume and it will use even more water. Remember that this is really a cactus and will be injured by too much water more easily than too little water. However, it is a cactus native to tropical rainforests where it is never as dry as the desert where we expect cacti to grow. Allow the soil to dry between waterings, but then once the soil is dry, water again.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

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