Gardeners Checklist: Here Is What to Do on the Week of Feb. 3

By Ron Kujawski

* Mix a solution of water-soluble fertilizer. The first week of each month from November to March is when I apply a water-soluble fertilizer to many of the plants I have growing indoors. Notice that I said “many” not “all”. Some houseplants, especially tropical plants, grow very slowly through the winter. I don’t bother to apply fertilizer to these until they show some growth in late winter or early spring. On the other hand, potted herbs and some house plants such as philodendron put forth new growth in winter. These do get fertilizer, that is, unless the potting soil contains some granular, slow-release fertilizer such as Osmocote.

* Keep in mind that pesticide applications to control insects and spider mites on houseplants must be repeated to get the best results. This is especially true when using organic pesticides such as insecticidal soap which work only on contact with the pest. Right now, I am battling an outbreak of aphids on potted thyme, rosemary, and a few tropical foliage plants. Hence, I am repeating insecticidal soap applications at seven-day intervals for three weeks. Though insecticidal soap and other organic pesticides are considered quite safe, do read and carefully follow label instructions on the product used.

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Other than a bit of Mother Nature’s mulch, a.k.a. snow, over our gardens, it’s difficult to complain about the weather this winter. Despite a few sub-zero mornings, it’s been rather mild at times. This has allowed me to move some house plants outdoors on days when temperatures rise above 40 degrees F. It’s a very brief stay, lasting only about twenty minutes or so, brief enough that not even tropical plants take offense. Why bother, you ask? There are two reasons. First, this allows me to drench the soil in each pot with repeated doses of water – tepid water that was warmed indoors. This thorough watering is done to leach out salts that have accumulated in the soil. These salts are residues from fertilizers and from the evaporation of water. By doing this outdoors I can be my usual sloppy self without fear of leaving puddles of water on the floor or muddy soil in the bathtub – my preferred indoor locale when doing this leaching process indoors. My wife concurs.

Another reason for moving some houseplants outdoors on mild winter days relates to the application of pesticides. I don’t like to apply pesticides indoors, even the most innocuous ones. As mentioned in the item above, insecticidal soap must come in direct contact with the pest. That means the insecticide must be applied to all surfaces of the plant, including the lower surfaces of leaves. Label directions on insecticidal soap say to apply the material until it drips from the plant. That can be messy when done indoors. So, messy plus my inherent sloppiness adds up to making these applications outdoors whenever possible. Again, my wife concurs.

Ron Kujawski began gardening at an early age on his family's onion farm in upstate New York. Although now retired, he spent most of his career teaching at the UMass Extension Service. He serves on Berkshire Botanical Garden’s Horticulture Advisory Committee. His book, Week-by-Week Vegetable Gardener’s Handbook, is available here.