December 30, 2012

Maine Gardener: Hallelujah – houseplant help is here


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There are diseases and pests that can affect houseplants but -- and Milliken repeated this one several times -- if you do not overwater you can avoid root rot and fungal diseases.

Scale and mealy bugs, which are related, are a common problem that Milliken said can be controlled easily with Imidacloprid, the active ingredient in Bayer Advanced products check your local nursery or hardware store). He said the systemic works better when applied to the leaves rather than as granules on the soil.

For those opposed to such chemicals, you can apply canola oil or other vegetable oil once a month in  modified indoor version of dormant oil spraying.

Spider mites are a bigger problem, but there are products from Bayer and Bonide that will deal with those. Neem oil products work on aphids. 

Pruning and repotting houseplants depends on the plant -- and the person, Milliken said. Some people like the plants to have a certain shape, and they will prune them more often, but it probably does not have to be done more than twice a year.

Repotting varies by the plant. Some plants like to be pot-bound (clivia being the one that comes instantly to mind), but Milliken said that on average once a year repotting would be the most required.

"With succulents, you sometimes have to repot because the tops get so big they will tip over if you don't put them in a bigger pot," he said.

Milliken believes that houseplants should be taken outside during the summer.

"They love the fresh air," he said. "The inside air gets stagnant. And they are getting fresh water, which is different from city water, with all the chemicals in it."

He did advise that when you first put the plants outside, you should keep them in the shade and out of the wind for a few weeks until they have adjusted. And when you bring them back inside as our weather turns cold, don't worry if some of their leaves yellow and drop off, they will recover. 

And watch carefully for insects and other visitors that may have come inside in the plant pots.

Tom Atwell has been writing the Maine Gardener column since 2004. He is a freelance writer gardening in Cape Elizabeth and can be contacted at 767-2297 or at:


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