Miniature Violets Not Blooming in Windows

Question:  I grow all of my violets in windows.  My standards do well, but I can’t seem to get my miniatures to bloom.  Any explanation?

Answer:  Most of today’s miniature varieties bloom just as well, or better, than do the standards.  Miniatures do seem to prefer a bit more light than do standards, though most will bloom under the same conditions.  For example, our miniatures are grown 10-12″ below two florescent bulbs (used 13 hours a day), while the standards are 18″ below the bulbs.  When growing in windows, this means that plants should be arranged in a way so that miniatures receive more light than standards.

I believe the reason this is a common complaint among those growing both minis and standard varieties in windows is because minis often receive less light, rather than more.  Space is always limited in a window, especially for those of us who always grow more plants than we have room for.  Minis, because they are smaller, usually end up being placed between or beneath the larger plants around them.  Also, plants are usually arranged so that they can be viewed from the interior of the room, not viewed from outside through the window.  This means that small plants are placed in “front” closer to the room (and farther from the window), with the larger, taller, plants in the “rear”.  This is an attractive arrangement, but one that means the small plants in front are being shaded by the larger plants nearer the window.  Is it any wonder that minis don’t bloom as well as their larger neighbors?  They’re always placed in the worst possible light!  Remember, just because they’re small doesn’t mean they should be hidden or neglected–give them the same light and care as your bigger varieties and they’ll perform just as well.

Hours of Light

Question:  I grow some of my violets under artificial lights on a light stand very close to my kitchen window.  My miniature violets are about 10″ below the tubes.  How many hours should I keep the lights on?

Answer:  We also grow our minis about 10″ below the tubes, with our standard-size varieties about 18″ below. Our lights remain on about 13 hours each day.  These plants, however, receive no supplemental natural light.  We do have two growing areas that receive a great deal of natural light as well.

The first of these are standard violets that we grow under florescent lighting on the lower shelf of a large bench in the glasshouse.  During the summer, especially, these plants get a good deal of additional indirect sunlight.  Because of this, we give them only 10 hours of artificial light during these months.  We also grow many of our plants, including all of our showplants, in a room with many very large windows–the south and west walls are nearly all glass.  Because we need to equalize our electricity usage throughout the day, we keep many of the lights turned on at night.  As a result, the plants never really have a period of total darkness.  From experience, we’ve learned that most of these plants do well only if lights are kept on for 10 hours or less, sometimes as little as 8 hours, a day.

A precise answer can’t be given, since it depends upon that particular growing environment.  But it is safe to say that less artificial light needs to be provided in the presence of supplemental natural light.

Choice of Bulbs for a Light Stand

Question:  I’ve been growing my African violets under lights.  I’m expanding my growing space and am wondering if I can simply double the number of florescent lights if I double the width of my shelves–i.e. if I have one tube for 20″ wide shelf, can I use 2 for a wider shelf.

Answer:  Assuming you don’t change the type of bulb, yes.  Nowadays, though, not all bulbs are the same and it’s become more complicated.  Over time, we’ve replaced most of our T12 fixtures with those using more energy efficient T8 bulbs which, as a rule, are much brighter.  We’ve actually found that we can get away with using only one T8 bulb for many varieties (we simply unscrew one of the two bulbs in the fixture), we we had used two T12 bulbs.  Whatever the bulbs, try using fixtures with solid-state (not magnetic) ballasts.  This will save you on electricity use and will produce far less heat.  This can be significant if you have more than a few lights, especially in summer, when heat can be an issue.

Shopping for lights has gotten more complicated.  There are dozens of different sizes and types, and each will produce different amounts of light.  Look for the light output (lumesn) on the label–there can be significant differences between bulbs.  ‘Color temperature’ (i.e. 5000k, for example) will also be listed.  In our experience, this is of less importance (though higher is generally better).  Whatever you decide to use, let your plants decide what is best.  If your violets look healthy, have good color and bloom, then all is well.  If they bloom, but new growth is crowded and leaves are off-color, it may be too bright.  If the color is good, but leaves don’t lay flat and blooms are sparse or infrequent, you likely need more light.  Adjust bulbs, distance from bulbs, hours of light, and placement of your plants on shelf (center of shelf for more light, outside of shelf for less) until you get the best results

How Long to Keep Lights On?

Question:  I grow some of my violets in a window and they do well there, except for the winter when they don’t seem to bloom very much.  I’ve added florescent light above the plants and really like how they look with the extra light, especially at night or when the days are dark.  Would there be any problem in keeping the light on all the time?

Answer:  So long as the light isn’t too intense, probably not, at least during the winter when you don’t seem to be getting much in the way of natural light anyway.  Though prevailing wisdom says otherwise, our experience is that violets can be successfully grown even when not given periods of darkness.  We have to areas in our shop where many plants, including violets, are grown with 24 hours of light.  Both of these receive light from both natural and artificial sources.  We do this for much the same reason–it makes the shop windows more attractive at night to passersby.  Of course, if you are doing this for your own pleasure, there’s no need to keep plant illuminated while you’re asleep!

As for whether your violets benefit, leave this decision up to them.  If they bloom and the foliage is green and grows well, then the plant is happy and the light is fine.  If they are receiving too much light, as might be the case during times of the year when there is more sunlight, foliage may become pale and brittle, new growth may become crowded in the plant center, and leaves may “hug” the pot.  If this becomes the case, reduce the time and/or intensity of the artificial light you are providing.

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