Indoor Plant Culture: Six Factors

Indoor plants need the right balance of light,  temperature,  soil, moisture in the air, water, and food.  Luckily many indoor plants like the same conditions as humans and many are not that fussy.   

Some beginner plants would include:  Pothos (Devil’s Ivy), Heart leaf Philodendron, Peace Lily, Cast Iron Plant, Spider Plant, Snake Plant.  

The Boston Fern and Snake Plant in the photo are easy to grow. 

• ​LIGHT: most important factor, indirect or direct, low-medium-high light, placement of plant, duration of light (14 hours sufficient, as plants need a rest too), type of possible supplemented light (blue & red wavelengths, infra-red, incandescent, or special grow lights.
• TEMPERATURE: warm is good, mostly tropical plants, ideal daytime 70-80 degrees, nighttime 65-70
• POTTING MEDIA: lightweight, drain well & retain water and nutrients. Buy commercial mixes are soilless, containing peat moss, vermiculite, or perlite.  NOTE: Avoid purchasing "potting soil" or "garden soil." which are usually too dense If you do purchase, add vermiculite or perlite to loosen the soil and improve drainage. If using slow-release fertilizers which will meet a plant’s nutritional requirements for several months; once used by the plant, add a fertilizer to promote plant growth. 
• RELATIVE HUMIDITY (RH) is the amount of moisture in the air relative to temperature and it helps determine what the temperature "feels" like.  Most greenhouses have a RH of >50%. Water loss in plant material is directly related to the RH—drier air will wick moisture from the plant more quickly. The ideal RH in homes is 40-60%. Ways to increase relative humidity near plants: 1) Group plants together to create a microclimate, 2) Use a humidifier, 3) Mist or spray plants? Super impractical, as you would need to do this every few minutes, 4) Pebble trays? Research found they really don’t work or increase humidity much.  Houseplants can increase relative humidity: Relative humidity is especially important in dry climates because it makes life more comfortable. In homes and buildings, the relative humidity is generally <60% (and lower in most cases). When only 2% of the space is occupied by plants, they can increase RH by over 5%! Don’t worry⁠—it won’t get too humid indoors; plants regulate their water loss based on humidity levels.
• WATER is the second most important factor for your plants. It’s going to take some practice and getting to know your plants and the environment before you get it right. Watering should never be done on a schedule! Plants are killed equally from over- and under-watering. So, it's best to select the plant that works best for you.  Light needs don’t equal watering needs, but higher light levels will result in greater water needs.  Plant and container size will determine how much and how often to water.  Media type will influence watering needs.  
  There are plants susceptible to fluorine and chlorine, which are added to most municipal water sources, such as corn plants, spider plants, and plants with longer leaves. To help with water quality, allow water to sit out for several days—the chlorine and fluorine will dissipate.
  WATERING TIPS 1) Always water enough to let water drain from the container. 2)Do not leave plants sitting in standing water in their saucer—discard excess. 3) Water plants when it feels dry up to the first knuckle or when your plants are drooping! 4) If you aren’t sure, use a water meter.
• FERTILIZER: indoor plants need to be regularly fertilized during active growth periods (April to September). The size of the plant and the container will determine how much fertilizer is needed.  1)Applied only if the plant is showing signs of deficiency (i.e. purple or yellow leaves), 2)It’s better to apply small amounts of fertilizer as the plant grows—use a ¼ rate for bi-weekly or monthly applications, depending on the foliage color, 3)Find your favorite brand and follow the instructions on the label, 4)To help avoid a salt buildup in the soil, leach the pot every 4 - 6 months by pouring a large volume of plain water into the pot and allow it to drain through completely. You can use a saucer to complete this task, or do it in the sink or bathtub.

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Master Gardener Vicki Gee Treft writes about what she learned from a "HOUSEPLANTS" course presented by Katie Dunker from the Colorado State University Extension.  
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A future posts will provide how to deal with pests and diseases.