Kinzler: Easy holiday cactus, tomato pollination and nutrients in snow

In today's "Fielding Questions" column, Don weighs in on how to grow hydroponic tomatoes indoors.

A reader's Christmas cactus began blooming after the recent snow. Special to The Forum

Q: With the recent snow, it not only looked like winter outside but the Christmas cactus also thought so. — Richard Witte.

A: Thanks for the great photo. Many of us are experiencing the same thing, with holiday cactuses blooming earlier than usual. I think our early spell of cool, wintry weather triggered the onset of buds.

Holiday cactuses, which include Thanksgiving, Christmas and Easter types, are triggered into flower bud formation by an interaction of cool nighttime temperatures and/or long, dark nights. Windows often have a slightly cooler microclimate than the room's interior, which helps to trigger bud formation. This year’s early stretch of cold, snowy weather across the region helped create cool zones inside many windows, helping cactuses to flower.

For anyone experiencing a holiday cactus that won’t bloom, try putting it close to a window that gets cool at night. If temperatures can’t be dropped low enough, down into the 60s within the window zone, cactuses can be coaxed to flower by putting in a window in an unused room that remains dark in the evening, without electric lights interrupting darkness. Cool temperatures are the easiest trigger to accommodate, but if that fails, long, uninterrupted night darkness is a secondary trigger.



Q: I’m growing hydroponic tomatoes indoors. Do I need to pollinate them with a brush? — Birgit P.

A: Outdoor tomatoes are pollinated more by wind than by insects. The air movement vibrates the flowers, which contain both male and female parts within the same flower. The movement causes male pollen to be shed and land on the female part.

For tomatoes grown indoors, the wind's movement can be duplicated by gently shaking the branches containing flowers. An artist's paintbrush could be used to gently sweep inside each flower. Commercial greenhouse tomato growers often use vibrating equipment. An electric toothbrush can even be used to vibrate each flower.

The University of Maryland conducted research on greenhouse-grown tomatoes in which a leaf blower was used on plants, dramatically increasing production. As shown, there are multiple ways to shake the flowers enough to distribute the pollen within each flower.

Q: Is the wet snow that fell recently and covered my blue spruce branches beneficial to the needles? My mature evergreens are heavy laden with snow. Do the needles absorb this moisture and is there nitrogen in snow to help the trees going into winter? Also, should I water them good before the ground freezes? — Dean L.

A: The question of whether snow has fertilizer benefits is addressed by Michigan State University: "Snow can also contribute to soil fertility. Snowflakes trap dissolved organic nitrogen, nitrate and ammonium in the atmosphere, delivering it free-of-charge to cold and quiet fields. Rain and snow together provide between two and 22 pounds of nitrogen per acre each year. But even the wildest winter storm isn’t a substitute for other forms of fertilizing."

The University of Minnesota, likewise, says snow contains nutrients, but not enough to support plant growth.

Every little bit helps, I suppose, so depending on the environment, research does show there is a small amount of nitrogen fertilizer in snow. Although leaves and needles can absorb nutrients through their foliage as well as roots during the growing season, it's debatable whether the needles can do this during the dormant season. When wet snow lays on evergreen branches, branch breakage is always a possibility, so the snow and its small nutrient load are better landing directly on the ground, rather than absorbed through needles.


Soaking the soil around evergreens before the ground freezes solid helps mitigate winter damage from the effects of sun and wind.

If you have a gardening or lawn care question, email Don Kinzler, NDSU Extension-Cass County, at Questions with broad appeal may be published, so please include your name, city and state for appropriate advice.

Don Kinzler column mug.jpg
Don Kinzler, "Growing Together" and "Fielding Questions" columnist.

Don Kinzler column mug.jpg
Don Kinzler, "Growing Together" and "Fielding Questions" columnist.

Don Kinzler, a lifelong gardener, is the horticulturist with North Dakota State University Extension for Cass County. Readers can reach him at
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