Poinsettias are now easier to grow, still hard to get to bloom

By Jeff Rugg
Copley News Service

Q: I was able to keep last year's poinsettia alive all year. It sent out a lot of new growth and it looks pretty nice. I have heard there is some special way to get it to bloom. How do I go about the process of making it bloom for Christmas?

A: I am afraid that this Christmas you will have to buy a new plant that is already in bloom if you want a blooming plant. Poinsettias are sensitive to the changing day-length and they need a couple of months worth of short days and long nights before they will bloom.

In a home environment, where people turn the lights on as it gets dark outside, the poinsettia doesn't get a long night. The lights will fool the plant into thinking that it is still summer. Even streetlights outside a darkened room can keep a poinsettia from blooming.

Next year, beginning around Oct. 1, the plant must be kept in total darkness for 14 continuous hours every night. Covering it with a box and placing it in a closet is good. The nighttime temperature must be between 60 degrees and 70 degrees. It needs bright sunlight during the day and it should be blooming between Thanksgiving and mid-December, depending on the cultivar.

Poinsettias provide a bright focal point indoors when the landscape is so drab outdoors. The colorful part of a poinsettia is specialized leaf called the bract. The real flowers, pea-size, are found in yellow and red clusters at the end of the branch.

When choosing a plant, here is what to look for.

Good quality plants have dark green leaves all the way to the bottom, no dead spots on the leaves and true flowers that are just starting to bloom. If the yellow powder-like pollen is dispersed and dried up or the true flowers are dried up, skip that plant. If any of the bracts have dried and dead edges, skip that plant, too. If the lower leaves are turning yellow, or fall off with just a slight tug, go to the next plant. If you turn over a leaf and it is covered with small white insects, don't buy it.

Another problem with many new poinsettias is that they are brittle and lose branches easily. Look for plants with vertical stems and few horizontal ones, especially if it is going to be taken home in a paper sleeve. Some growers install a plastic ring on the pot that supports the branches about 5 inches above the pot rim.

Plan for the right day to buy your plant. Do not expose the plant to near-freezing temperatures while taking the plant from the store or leave it in the car while doing more shopping.

Once home, don't expose the plant to drafts of any kind (especially plants on the floor) or direct sunlight. Keep the soil evenly damp all the time. Check the plant daily at first, until you determine how much water it will need. Big plants use a lot of water. They prefer temperatures from 65 to 75. The cooler temperature makes the flowers last longer. Putting it near a heat-generating appliance (TV, photocopier) will shorten its flowering lifetime.

If it dries out, it will begin losing leaves. If it is over-watered or left to sit in water, the roots and then the whole plant will die.

Poinsettias are members of the spurge family. They contain a milky sap that can cause a rash, but the flowers and bracts are not poisonous, as many people believe.

They are native to Mexico and Central America, where they grow as shrubs to more than 6 feet tall. The Aztecs cultivated them hundreds of years ago. In the 1800s, the United States' first ambassador to Mexico was Joel Poinsett. He was also a botanist, and he brought the plants that now bear his name to his greenhouse in South Carolina.

If you want high quality, new varieties or different sizes of plants, you will have to shop at a florist, greenhouse or nursery, not at the grocery store or hardware store.

Until recently, poinsettias were finicky. They would lose their bracts at the slightest change in temperature or watering. Taking them home on a cold day could do them in. The new ones have much longer-lasting bracts, sometimes even until spring.

Poinsettias are beautiful plants that come in many shades of red and pink. Some newer varieties are mottled or even come in yellow. There is also a wide selection of sizes available, from a 4-inch plant that can be worn as a corsage to 6-foot trees.

Although poinsettias are easy to grow, they can have problems. Any crop that is grown in large quantities can have insect or disease outbreaks. The worst insects to control in your home are white fly and spider mites. Both are pests on poinsettias and you should look for them before you buy the plant.

Do not use insecticide soaps on poinsettias, because it is more likely to kill the plant than the pests. Spider mites can be washed off with water. White flies can be controlled with a pyrethrum-based insecticide or malathion.

Several other plants make great indoor decorations in the winter. Try cyclamen, azaleas, hydrangea, miniature roses, orchids, African violets, anthurium and any others that your florist recommends.

There should be no reason you do not enjoy fresh flowers all winter long.

E-mail questions to Jeff Rugg at jlrugg@pondsupplies.com.