Indoor gardening tips from a Becker County Master Gardener
Editor's note: This is the first article in a three-part series about growing plants indoors, from Becker County Master Gardener Nicholas Williams. Future articles will explain hydroponics and aeroponics. This one is about growing plants as they grow outdoors — in dirt.
There are many reasons for growing plants inside, but the only reason that is logical is simply to enjoy the sight or smell of them.
One cannot realistically save or make money by growing any plant — edible or not — inside. Indoor plants do not purify the air, nor affect the humidity in one’s home. Indoor plants do not affect the oxygen or carbon dioxide levels in the home, and there is no concrete evidence that plants can alter one's mood directly — unless one ingests a specific plant in some way.
Many people grow plants indoors and have reasonable success, having learned the ropes through trial and error or through observation of family and friends. Most people are quite successful and need no advice, so I intend to speak to the neophyte — one who does not grow stuff inside but wants to start. First of all, I would suggest buying plants as opposed to starting from seeds.
What kind? Consider Zamioculcas zamiifolia — the ZZ plant. This is a native of eastern Africa and is nearly impossible not to grow. Many say it is not pretty, but it is a plant. A related plant is pothos, or devil’s ivy, which is pretty and grows as trailing ivy. (This variety is mildly toxic, so households with children or cats may be advised to avoid). Chinese evergreen is easy to grow, as are asparagus fern, spider plants and English ivy. Aloe is also nearly indestructible. There are hundreds of other plant types that will grow well and easily in your home — ask the person at the store.
Where? All plants need sunlight in various amounts, and the best information about how much is on the tag that comes with the plant. Near windows is always best, and at this latitude (north of the 45th parallel), one might consider augmentation of sunlight with electric lights. LED lights have become inexpensive and are available in the specific wavelengths that plants use. If one uses artificial light, it is imperative to use a timer, since the amount of darkness is what sets a plant’s internal clock and if that changes randomly, the plant may get "confused." Timers should be set to prolong the afternoon light by 2 or 3 hours every day, starting in the middle of November, decreasing in March to zero extra light by the end of March.
How? Besides sunlight, all plants need water and nutrients, but not as much as one might think. Over watering is the most common cause of indoor plant death (over fertilizing runs a close second). Very few plants need water more than once a week, and many don’t need that much. Add water when the soil is dry, not necessarily when the plant looks droopy. If the soil can be compressed into a ball and it retains that shape, there is enough water in the soil. Too little water is better than too much (up to a point).
Most potting soils contain enough nutrients to last years, and have the acid content adjusted and buffered in such a way that these nutrients can be easily used by the plant. For indoor plants, it’s probably best to use commercially available soils, unless you’d care to have your soil analyzed for pH and nutrient content. These "potting mixes" drain well, hence rocks and debris at the bottom of the pot are unnecessary.
Dead leaves, stems and flowers should be removed when seen. Plants should be pruned to control size and shape in the fall. Terra Cotta pots are the best.
Temperature? If there is ice on the inside of the window closest to the plant, it is probably too cold. Don’t put plants between the curtains and the glass. A plant should not be in the path of air blown from a heater.
It is time to put your plant into a larger pot when the exposed dirt is hard to penetrate with your finger, or if water simply sits on top of the soil without soaking in, or if you can see roots coming out the drain holes at the bottom. If the plant stays healthy and grows well, repotting will be necessary every 12 to 18 months. Spring is the best time to re-pot.
Pests, problems? Fungus gnats (some people call these "fruit flies") are an indicator of over watering. Spider mites are almost inevitable, it seems — insecticidal soap applied weekly until they are gone is effective for these, as well as for aphids. This would be applied (after dilution as explained on the label) with a misting sprayer.
Houseplant diseases such as fungus leaf spots, powdery mildew and root rot can be treated, but sometimes it is best to simply discard the plant and replace it before the disease spreads to other plants.
Houseplants are an effective way to beautify one’s home; growing them is easy and gratifying, as well as inexpensive. I believe there should be at least one in every room.