10 steps to better houseplants
In today's "Growing Together" column, Don Kinzler offers advice for anyone to find their green thumb and step up their indoor gardening game.
Have you ever wondered who first brought a plant indoors and declared it a houseplant? Cave people were probably busy with other pursuits, so it likely came later.
We know that by medieval times, indoor plants were grown in grand conservatories on royal estates. When did houseplants become a popular pastime for the rest of us?
We can thank the Victorians and the development of central heating in the late 1800s for creating a home environment with a temperature stable enough for houseplants, which are mostly tropical natives accustomed to consistent warmth.
Gardening remains America’s leading pastime, and tending houseplants tops the list with many homes and apartments having at least a houseplant or two.
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The following are steps to greater houseplant success.
- Deciding when to water is the most challenging part of houseplant care. As a guideline, whenever we water, enough should be applied to wet the soil thoroughly so a small amount seeps out the bottom drainage hole. Then let the soil dry considerably before the next watering, which pulls necessary oxygen inward. When a finger inserted up to the first joint feels dry or barely moist at the tip, the plant is ready to be watered again. If the soil feels quite moist at the fingertip, delay watering a day or two. Develop a cycle of thorough watering followed by considerable drying. Experience is the best teacher as we develop a feel for watering.
- I’m often asked how often to water houseplants, such as once or twice a week. Watering on a set scheduled can be difficult. Instead, we can schedule certain days to check our plants, but water only if needed. Frequency varies by size of pot, type of plant, amount of light, indoor humidity and season of the year. Overwatering is a common killer of houseplants, which means the soil is kept continually too soggy. It doesn’t mean applying too much at one time, because the excess will escape through the pot’s drain hole, and should be discarded immediately. Watering too frequently with small amounts contributes to overwatering.
- The best water for houseplants is rainwater, melted snow and reverse osmosis water. Water purified by city water systems using ozone is better than chlorinated water. Water run through a mechanical softener is high in salts and is best avoided.
- Top-quality potting mix is essential. Inexpensive bargain mixes are heavy and poorly aerated and contribute to overwatering problems. Instead use high-quality products like Miracle-Gro Potting Mix, or mixes recommended by your locally owned garden centers. Because these mixes are usually sold dry, add water to the bag and mix well the day before using to create a mellow, workable moisture content.
- When potting a houseplant, fill the pot to the rim with soil mix, which will settle when watered. If the “headspace” between the pot’s rim and the soil surface is greater than about a half inch, chances of overwatering and other problems increase. When I’ve observed failing houseplants, a too-deep headspace is often visible.
- There’s great leeway in how often to repot houseplants, and once every two to three years is average. Some plants grow beautifully in the same pot for decades. Most plants enjoy being slightly pot-bound, rather than wallowing in a too-large pot and soil volume.
- Drainage pebbles or stones aren’t needed inside the bottom of a pot. Although they were standard practice years ago, research has shown these materials cause a layer of change, which actually impedes the drainage they were intended to provide. Best drainage occurs when a pot is filled top to bottom with potting mix. High-quality mix rarely seeps out the bottom drain hole, so there’s no need for a coffee filter or diaper to be added.
- Reserve fertilizer for healthy plants. If plants are in a downward spiral, insufficient nutrition is rarely the cause, and fertilizer isn’t medicine to revive a sick specimen. Fertilize once a month March through September when daylight is long. Plants require less during the short days from October through February.
- Houseplant types vary by light requirement, so investigation is needed to determine whether a specific plant must be near a window or can be located in a room’s dimmer interior.
- Most of all, enjoy your plants, and they’ll respond like a well-cared-for pet.
Don Kinzler, a lifelong gardener, is the horticulturist with North Dakota State University Extension for Cass County. Readers can reach him at firstname.lastname@example.org or call 701-241-5707.