1 - My houseplants have gotten too large to bring indoors. They will not fit where I kept them last winter. Is it OK to trim them back?

Yard and Garden September 12, 2009

Q.

My houseplants have gotten too large to bring indoors. They will not fit where I kept them last winter. Is it OK to trim them back?

- J.T.

Socorro

A.

Congratulations, it is a good thing that your plants grew well outdoors this summer. Your plants should now have built their strength up to deal with the stressful indoor environment. But, as you mentioned, they must "fit" in the space you have for them indoors. Some plants can be pruned back, but others may not respond well to pruning. The manner in which they respond depends to a large degree on the growth habit of the plant. Woody plants with branches that respond to pruning by producing new shoots can be pruned. The common Benjamin's Weeping fig is an example. However, the process of producing new shoots consumes the stored food that the plants have put away to sustain them through the winter. Past experience regarding how well the plants grew indoors and the specific environment inside your home determine which you can trim back. If the plants have grown and flourished indoors and if the wintering site has adequate light (many hours of bright light, not direct sunlight), then the plants will tolerate more pruning.

Another option is to propagate new, smaller plants. In much of New Mexico there is still time to take cuttings from oversized plants and produce replacement, smaller plants. If the plants are not protected by plant patent you can propagate the plant vegetatively by cuttings (a label in the pot when you bought the plant will indicate if it is currently under patent protection). To propagate the plants by cuttings you can take a young, healthy stem from the plant, dip its cut end into rooting hormone and place this cutting into a small pot of fresh pasteurized, potting soil. And then you can place the cutting and its pot into a plastic bag (clear or white) in a well lighted location while the roots form. After 2 weeks to a month the cutting should have new roots. Gradually open the bag to allow more and more fresh, drier, air in around the new plant. If the plant wilts, reclose the plastic bag, but if it tolerates this, remove the bag and your new plant is ready for its winter indoors. Since the purpose of starting new, smaller plants was to make room for the plants indoors, you will probably want to discard the original, overgrown plant or give it to a friend.

Some plants will not so easily produce roots from a cut stem, but may be induced to produce new roots by the process called layering. That usually takes longer, but can be done indoors during the winter. In the "layering" process, the stem is wounded by slicing through the bark slightly, but not cutting the stem from the parent plant. The wound is treated with rooting hormone and wrapped with damp sphagnum moss. The moss is then wrapped with plastic and sealed above and below the sphagnum moss to keep the moisture inside. Once roots have formed, the stem can be cut below the sphagnum containing the new roots and potted to create your new plant.

There are other useful propagation techniques that will allow you to create new, smaller, plants for the winter. Some plants will propagate easily now, others may need to be propagated next spring or summer. Propagating your own, new plants is an enjoyable part of gardening and helps you keep your houseplants sized properly for their location indoors.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

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