Caring for poinsettias after the holiday season


For the readers that bought poinsettia plants for the holiday season, here are some tips for the care of the plants once they are taken home:

— Unwrap the plant and place in indirect light. Six hours of light daily is ideal.

— Poinsettias require daytime temperatures of 60 to 70 degrees and night time temperatures around 55 degrees for best growth. High temperatures will shorten the plant’s life. Move the plant to a cooler room at night, if possible.

— Be sure to punch holes in the foil so water can drain into a saucer, discard excess water. Check the soil moisture often. Water when soil is dry.

— Fertilize the poinsettia in order to keep it past the holiday season. Apply a houseplant fertilizer about once a month. Do not fertilize when it is in bloom.

I have written this article previously, but the question continues to appear: Are these beautiful Christmas season plants poisonous?

No, this myth has been around since the early 1900s. The American Society of Florists has been trying to dispel this myth for a long time. They say that no other consumer plant has been tested for toxicity more than the poinsettia.

According to the “American Medical Association’s Handbook of Poisonous and Injurious Plants,” ingestion of the poinsettia plant has been found to produce no effect except an occasional case of vomiting. According to the POISINDEX information source, a child who weighed 50pounds would have to eat more than 500 poinsettia leaves to reach a potentially toxic dose of compounds in the poinsettia plant.

Since the taste of poinsettia leaves is reportedly very unpleasant, it is unlikely that a child or animal who attempts to eat or chew the leaves will continue to do so after the first taste. Some people, however, can develop a skin and eye irritation from contact with the milky sap of the plant.

Ambrosia Beetle on Avocado

Aloha, We appear to have a pesky beetle boring into our avocado trees. What can we do to stop them? We are in Discovery Harbour, Naalehu. Thanks, in advance, Fran

The black twig borer is an ambrosia beetle which attacks avocados as well as podocarpus, coffee, citrus, lychee and many others in Hawaii. Since I have written on this subject in past columns, you can read an in-depth report on it on the UH-CTAHR website or www.gardenguyhawaii.com.

Control is difficult since the larval stage of the beetle is inside the twigs or branches. A long lasting residual insecticide would need to be applied in order to kill the adult as it periodically lands on branches to excavate a nest.

Fortunately, this pest usually causes minor damage. Twigs will die back from the point of entry to the end.

Pruning out and proper disposal of the beetle-infested plant material is essential. In addition, good tree care to promote a vigorous and healthy plant will help in resisting infestations and recovering from old ones.

As mentioned, under most conditions the tree should be able to survive attacks of the beetle. There is some biological control activity against this pest.

Leafminer

I am trying to grow vegetables in containers but have problems with what appears to be leaf miners with characteristic white tunneling lines in the leaves. What do you recommend to control this pest? Thanks for your help! Kurt K.

Chemical sprays are usually not recommended because the larvae are well protected inside the leaf tissue; consequently, sprays are of little benefit. In most cases though, leafminer damage can be tolerated. Why? Because several species of parasites (the good guys) attack the larvae while they are feeding within the leaf tissue. The parasites will not eliminate the problem but generally will keep the infestation under control.

Damage is mostly confined to seedlings. Once they are set out in the garden, the plants tend to outgrow the pest while biological control takes over and keeps damage to a minimum. You will still see some tunneling from the leafminer, but the crop will continue to produce.

Hilo resident Nick Sakovich is a professor emeritus of the University of California. He has worked in the field of agriculture for 30 years. Email your questions to Sakovich at askthegardenguy@earthlink.net.

 

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