In this section of my website, you will find professional indoor plant care information not found elsewhere. It is based on 30 years of professional hands-on experience caring for indoor plants in office and residences. These are environments similar to your home and office. Other sources of indoor plant care information rely on experience in controlled environments such as greenhouses, nurseries and tropical rainforests.
What you read here may surprise you and conflict with what you have heard and read elsewhere. But I think you will find that it also answers many of your questions and will make sense to you.
Never repot a new plant and never repot any plant unless it is absolutely essential. Unnecessary repotting is the number one cause of plant failure. It is a common misconception that plant roots need lots of room in a pot. In fact, plants grow best when they are kept moderately potbound. As long as there is enough soil for the roots stay appropriately moist between waterings, then there is no need to repot. Repotting is not as simple as is commonly believed. Learn when and how to repot correctly by ordering a free copy of Indoor Plant Bulletin No.18.
Pruning is what keeps your plant looking young. It is the most neglected plant care technique. Why? Because plant owners fear they will do it wrong and kill the plant. In fact, pruning is quite easy once you overcome your anxiety about doing it. Pruning will alter the appearance of your plants, but it will not kill them. It is the only way to keep plants from becoming overgrown with long, bare stems touching the ceiling, bending over or crawling across the floor. I have written Indoor Plant Bulletin No. 24 to help you overcome your pruning fears and explain how to go about it.
Make sure your indoor plants get enough light. Most folks overestimate the available light in their homes. Even low light plants need to be within 6 to 8 feet of a sunny, uncovered window. Most other indoor plants must be within a couple of feet of a sunny window. The window must be uncovered throughout the daylight hours. Before you purchase a plant, evaluate the available light and select a plant based on that. If you have only low light, then you are limited to low light plant species (see Indoor Plant Bulletin No. 9 for a list of low light plants). If you have better light, then your plant options expand. Order a free copy of my Indoor Plant Bulletin No. 3 to help you assess light so you can make better plant choices.
When thinking about watering your plants, think instead about drying them out. Sounds crazy, but plants need oxygen around their roots as much as they need water. When you water, you fill the air pockets in the soil with water. If you don’t allow the soil to dry out properly, then you will deprive the roots of essential oxygen. The result is root rot. In general, most potted plants need the top 20-25% of the soil to feel dry to the touch before water is added. Moisture loving plants need water as soon as the soil surface is dry, while succulents need the soil to dry halfway down into the pot in between waterings. Know how much drying out your plant requires and focus on that when thinking about when to water them. Learn more about proper watering by ordering a free copy of Indoor Plant Bulletin No.4.
Everyone likes to fertilize. Presumably good health and vigorous growth are virtually guaranteed when you fertilize. Here is another surprise: fertilizer is vastly over-rated and guarantees neither health nor growth. The truth is that plants use nutrients in miniscule quantities. Good potting soils have an abundance of nutrients that will last for several years or more without any supplements. Light and proper watering are what will determine the health and growth rate of your plants. So if you want to skip the fertilizer, your plants will not notice. Finally, never use fertilizer as medicine to fix ailing plants. It is not medicine and will only aggravate the problem. Still not convinced? Learn all the specifics of plant nutrients, fertilizers and which brand you should choose by ordering a free copy of Indoor Plant Bulletin No.8.
Houseplants need high humidity, right? Wrong. Most common houseplants have proven to do quite well in very dry, indoor winter air even though these same plants are native to naturally humid environments. As long as you keep the roots well supplied with water, most indoor plants will do fine without added humidity. Daily misting to increase humidity is a waste of time. At best it raises humidity for 10 minutes out of a 24-hour day. If you want to increase humidity, buy a humidifier (your skin and furniture will also benefit) or set up humidity pebble trays under your plants.
Plants and Oxygen
There is a widespread notion that plants steal oxygen from the air at night and should not be used in bedrooms. Plants use carbon dioxide during the day to produce photosynthesis and oxygen that is emitted into the air. At night when there is no light for photosynthesis, the process is reversed and plants use a slight amount of oxygen. However, the oxygen debt at night is far less than the oxygen added during the day. So feel free to keep plants in your bedroom as long as there is enough light to keep them growing. The plants will not only add oxygen, but they help filter air pollutants.
Plants and Domancy
You may be surprised to learn that most indoor plants do NOT have a dormant period in the winter. Indoor plants are native to tropical regions where temperatures and light are fairy constant throughout the year. Although the hours of daylight available for plants indoors are shorter in winter, the reduction in light slows plant growth only a bit. Because they are non-seasonal, most indoor plants can be pruned and repotted at any time of year.
Here are the names of some common indoor flowering plants that DO have dormant or semi-dormant periods, usually in the fall: Amaryllis (dry), Anthurium (cool), Azalea (cool), Camellia (cool), Christmas Cactus (cold), Gardenia (cool), Gloxinia (dry), Hibiscus (cool and dry), Kalanchoe (short days), Oxalis (dry), and Poinsettia (short days).
Watering by weight
Some people decide when to water by the weight of the pot. I don’t recommend this technique for beginners. Growers use many different potting mixes and some are naturally heavier than others. The same plant potted in two different potting mixes with both at the same level of dryness will have different weights. If you have learned from experience just how heavy a particular plant is when it needs water, then this may be a good technique for you and that plant. Otherwise, use the more traditional method of probing the top of the soil with your finger to determine appropriate dryness before watering.