The no-fail recipe for houseplant success

Do you have a green thumb? Hopefully your thumb isn’t actually green, but the age-old term simply means you’re giving plants what they need to thrive.

Plants’ needs are pretty basic, including air, light, water and nutrition. Everyone can learn to provide what houseplants need, making green thumbs possible for everyone. With a can-do attitude and a few guidelines, anyone can enjoy success with plants.

Here’s a recipe that, if followed carefully, is guaranteed to help anyone grow houseplants.

• Begin with healthy, well-branched houseplants purchased from a garden center or florist, or well-grown plants gifted from friends or relatives. Spindly, weak plants are difficult to nurse back to health and can be discouraging. Begin your houseplant journey with good stock.
• Garden centers are filled with exciting new varieties of houseplants, and improvements on old standbys. Among the most successful types are heartleaf philodendron, cacti and succulents, dracaena, snake plant, pothos, spider plant, peperomia, peace lily and arrowhead plant.
• Plants that are purchased small might need repotting into a slightly larger container right away. As plants get larger, repotting once every two to three years is average. Most plants enjoy being slightly pot-bound, rather than wallowing in a too-large potful of soil.
• Plants will grow in pots made of clay, plastic, metal and ceramics, but traditional unglazed terra cotta clay pots are more tolerant of watering mistakes, because air and water can exchange through the pot’s sides.
• Top-quality potting mix is essential. Inexpensive bargain mixes are heavy, poorly aerated and contribute to overwatering problems. 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 material.
• Skip the pebbles, stones or other material in the bottom of the pot. Although they were standard practice years ago, research has shown these materials cause a layer of change that impedes the drainage they were intended to provide. Best drainage occurs when a pot is filled top to bottom with potting mix. There’s no need for a coffee filter or diaper lining the inside.
• When potting a houseplant, fill the pot to the rim with soil mix, which will settle when watered. If this “headspace” between the pot’s rim and the soil surface is greater than about one-half inch, chances of overwatering and other problems increase. When I’ve observed failing houseplants, I've often noticed a headspace that’s too deep.
• Study plant tags or search online for the light requirements of your plants, which can be divided into high, medium and low light. During winter, when days are short and sunshine is weak, most plants appreciate all the light they can get, including some direct sunshine. Summer’s intense sun usually requires filtering.
• When watering houseplants, apply enough to wet the entire soil ball 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 in doubt about whether to water, wait a day or two. More plants are killed by keeping them too wet, than too dry.

  

• I’m often asked how often houseplants should be watered. Watering on a set schedule is difficult. Instead, schedule certain days to check the 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.
• Rainwater, melted snow and reverse osmosis water are all good choices for houseplants. Water purified by city water systems using ozone is better than chlorinated water. Avoid using water that runs through a mechanical softener, because its high salt content can damage plants.
• Fertilizer is for healthy plants. If plants are in a downward spiral, poor nutrition is rarely the cause, and fertilizer isn’t medicine to revive sick plants. Fertilize houseplants once a month March through September when daylight is long. Plants require less during the short days of October through February.
• Above all, enjoy your plants, give them intentional care, and they’ll respond like a well-cared-for, happy pet.

Don Kinzler, a lifelong gardener, is the horticulturist with North Dakota State University Extension for Cass County. Readers can reach him at donald.kinzler@ndsu.edu.