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Holiday cacti

Posted: November 9, 2010 - 4:52pm

One blooms at Thanksgiving, the other at Christmas, but there are other differences, too

A physical difference between the Thanksgiving and Christmas cactus: Thanksgiving cacti have margins with pointed or serrated lobes and Christmas cacti have rounded margin lobes. Another difference in physical appearance is with the flowers. The Thanksgiving cactus has yellow anthers and the Christmas cactus has purplish-brown anthers.

Dear master gardener: I bought a Christmas cactus last year, but it is starting to bud and looks like it will bloom in November. Why is it called a Christmas cactus if it going to bloom for Thanksgiving?

There are two holiday cacti - the Thanksgiving cactus and the Christmas cactus, both of which are in the genus Schlumbergera. The difference is in the species; a Thanksgiving cactus is Schlumbergera truncate and the Christmas cactus is Schlumbergera x buckleyi.

A physical difference between the two is that Thanksgiving cacti have margins with pointed or serrated lobes and Christmas cacti have rounded margin lobes. Another difference in physical appearance is with the flowers. The Thanksgiving cactus has yellow anthers and the Christmas cactus has purplish-brown anthers.

The two plants also differ in the time they flower. In the northern hemisphere, Thanksgiving cacti flower around Thanksgiving and Christmas cacti flower during the Christmas season. These cacti flower in response to the shortening of the days. Thanksgiving cacti need longer days of light and therefore bloom approximately six weeks before Christmas cacti.

Both cacti are easy to grow as a houseplant and will bloom again each year, if taken care of properly. Keep them out of direct sunlight (near an east or west window is ideal), and when they are not blooming allow them to dry out between watering.

Dear master gardener: My neighbor is growing a pineapple plant, which she said she started from a pineapple she bought at the grocery store. Is this difficult to do?

It is relatively easy to grow a pineapple plant in your home. Purchase a pineapple at the grocery store. When it is ripe (but not too ripe) and you are ready to eat it, cut or twist off the crown (the leafy top). Make sure to remove any pineapple flesh sticking to the base, otherwise it will rot. Next, cut the bottom of the crown until you see the small, round root buds around the edge of the stem base. Remove the first set of leaves until you have about a 3/4-inch stem. Place the crown in a dry, dark place for one week to let the end harden. Plant your pineapple crown in an 8-inch clay pot with one inch of coarse gravel in the bottom, because it needs good drainage, then a light potting soil with 30 percent well-composted organic matter. When it outgrows this pot, replant your pineapple plant in a 12-inch clay pot.

Water your pineapple plant once a week, being very careful not to overwater it. Fertilize it every three months. Keep your plant near a sunny window but make sure when it gets cold to move it away from the window at night, as it is cold-sensitive.

Dear master gardener: Last summer, I had some lovely perennials growing in containers that I would like to overwinter and use again but I know they will freeze and die in their pots. Is there some way I can keep them alive over the winter?

If they are in large containers, repot them into smaller individual plastic containers and sink them into the garden. Make sure that they are buried up to the rims and watered well up until the ground freezes. They should also be covered with 2-3 inches of mulch. In the spring the pots will be easy to remove and replant. This will also work for small container-grown trees until they get too large to handle.

Dear master gardener: I have brought in my houseplants that spent the summer outdoors. They look great and I'd like to keep them that way over the winter. How can I do that?

The first thing you should do is to isolate the plants from those that spent the summer indoors so that they do not bring in harmful insects or diseases. Do that by washing down the foliage, placing them in a sink and gently spraying them with water to wash off insects. Then observe the plants for a couple of weeks and when you are sure that there are no insects or diseases, situate them in places appropriate to their need for light. Stop fertilizing to slow growth that indoor winter conditions cannot support. Water the plants regularly. Once a week is usually sufficient but most should be watered thoroughly, until water comes out the drainage holes. Pour off the drained water and never let plants stand in water. Some plants, such as cyclamen, will tell you that they are thirsty by getting droopy leaves. If you find disease or insects, treat them or discard the plants.

CROW WING COUNTY MASTER GARDENERS are trained and certified volunteers for the University of Minnesota Extension Service. All information given in this column is based on research and information provided by the University. To ask a question, call the Master Gardener Help Line at 824-1000, extension 4040, and leave a recorded message. A master gardener will return your call.