A lot of houseplants die, but they don’t have to. Their owners kill them — by trying to help them. They use too much water.

“Overwatering is the worst thing you can do,” said Dennis Milliken, a founding director of Merryspring Nature Center in Camden who works at Green Thumb Nursery in Rockport. “Houseplants would rather be on the dry side.”

Milliken said most houseplants need watering only about once a month. Even though Maine homes are dry during the winter, because the cold winter air gets drier as it is heated, that does not mean plants need a lot of water.

Temperature is not a big problem for houseplants, he said, even though most thrifty Mainers keep their heat low at this time of year.

“Most of the tropicals will take it OK on the cool side, as long as you don’t get down below 50 or 55 degrees,” he said. “You should try for bright light, of course, although some things will take a lot of shade.”

Which brings us to Milliken’s next advice: Pick the right plant.

When asked what are the easiest houseplants to grow, the first two he mentioned were peperomia and hoyas, and they are quite different — although they both will stand it if you forget to water them and they don’t need bright light.

Peperomia is a member of the pepper family, grown for its foliage rather than for its flowers. There are many different peperomias, coming in different colors, leaf shapes and plant shapes. Many of them are variegated, and the leaves come in different textures. They need good drainage and don’t need much fertilizer.

The hoya is a vine, and Milliken recommends letting it climb up drapery rods or other items so it shows itself off to the best advantage.

“Hoya is pretty, both for its foliage and its flowers,” he said. “When it blooms the flowers are very fragrant.”

But there are other plants that are quite easy, as well.

He likes streptocarpus because they are easy to care for and will produce flowers all year long. With good care, streptocarpus bloom prolifically, usually in a blue purple sort of trumpet-shaped flower.

“Bromeliads are a nice plant, and you don’t see them too much,” Milliken said. “They flower and they don’t take much work. As soon as they bloom, the mother plant is going to die, so you just divide off the pups and replant them, producing three or more plants. The flowers last for a long time.”

In watering bromeliads, you keep water in the small cups formed by the blossoms, and he said you can use those blossoms as a vase for other small flowers. We’ve had bomeliads in our house for years and only had problems with a cat who was allergic to them.

Milliken also suggested another plant that we used to grow: pittosporum. We had the variegated version which bloomed each spring with sort of an orange blossom fragrance.

Those are just a few of the houseplants mentioned by Milliken and you can try any of those if you haven’t had success in the past. But if you have experience, or after you have succeeded with these, you can branch out.

Go to a nursery or garden shop that has a plant specialist on staff, find a plant you like and ask the expert if that plant will grow in the conditions you have at home. The expert will be glad to give you advice.

Milliken said that plants don’t need much fertilizer and he suggests a quarter-strength fertilizer solution every time you water, which as he said can be as little as once a month.

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:

[email protected]