Keep Your Houseplants Out of ICU with Routine Care and Frequent Well Visits

Southwest Yard & Garden

By Marisa Thompson

Plants at my house huddled around the largest south-facing window. Note: green tinted saguaro light doesn’t actually help the plants. It’s just there for coolness factor. Note #2: Think saguaros won’t grow in New Mexico? Better think again! Check out my Dec. 2019 column, “Here Today, Gone Saguaro,” for the full story. Photo credit M. Thompson.

 

Question: What are your favorite tips for keeping houseplants healthy during the winter?

                                           - A. Thomas, Farmington

Answer: While the right amount of water and really good drainage are probably the biggest hurdles for plant parents, once you get those figured out, optimal lighting and microclimate are the next major concerns. These seem simple, but they’re particularly tricky in the winter months when the sun sits lower in the sky, days are shorter, and heater vents emit dry warm air. A medium-light plant, like cyclamen, might flourish all summer near a south-facing window with bright light and no direct sun but suffer in the same spot during winter when the sun blasts through all day. Meanwhile, healthy, established plants like my split-leaf philodendron may be able to adapt to the sunnier situation just fine.

When I temporarily moved a different split-leaf philodendron outside to the patio this September, it did not respond well. Within a day, the outer leaves turned almost white from sunburn because the plant had enjoyed a protected, bright spot indoors (without direct sunlight) before the move. Luckily, over the next weeks and more frequent watering, green leaves started forming from the base.. just in time to rush back indoors before the first frost. 

As I was bringing my houseplants in from their summer vacation spot on the patio in early October, I remembered that some thrived last winter and others suffered. I’m keeping a closer watch this season to catch the unhappy ones early and try a different location—or adjust the watering amount and frequency. Moving to a brighter place may be the solution if your houseplant isn’t looking so hot in a spot that doesn’t get much natural light. It could also be that you’re watering too much for such low light exposure.

If any of my houseplants die this winter, it will be because of too much or too little water. Generally, plants need less water in winter when they’re not growing as rapidly. As Bernalillo County Extension Agriculture Agent and Program Director John Garlisch says, the best soil moisture sensor is your finger. If the soil an inch or two down still feels moist and cool to the touch, you can probably wait longer before watering. If it’s moist, but you’re hurrying to leave town and are afraid it will dry out while you’re away, it’s okay to water a little extra this one time, but don’t make it a habit. Sometimes I move plants further from the window before heading off on a trip so they can last a little longer between irrigations—I’m looking at you, cuetlaxochitl (aka poinsettia).   

No matter what time of year, drainage is essential for potted plants. The dreaded “wet feet” is a problem in soggy soil because healthy roots need oxygen. (Of course, some plants have mechanisms for living in wet soil, but this isn’t the case for most houseplants.) Be sure water can (and does) flow freely through the drainage holes. If water pools in the saucer under your pot, it’s essential that you dump it before standing in water too long. After going through the messy trouble of dumping saucers a few times, I usually learn to avoid this chore by applying less water. Emphasis on “usually.”

The mistake of overwatering is tough because it can be way too easy to do. I once recommended to a retail nursery customer that she acquire a tiny, doll-size watering can because she didn’t have the heart to stop her ailing mother from watering the houseplants multiple times each day.

Converting a shot glass to my preferred watering vessel early in the pandemic probably saved my plants’ lives when I was home a lot more, way more anxious, and wanting to water every few hours.

Another common problem is potting up into a bigger container too soon or skipping the next size up and going for a jumbo pot. It’s problematic because the soil in the container without roots (that is, the soil around the outer edges of the root ball) holds moisture longer, creating a soggy situation that stinks, literally. Generally, hold off on repotting until the roots take up most of the space in the container. That is, when you carefully pull the plant out of the container and see thick, white-ish-cream-colored circling roots and relatively little soil, potting up could be beneficial (even then, though, it may not be necessary). If your soil dries super quickly, this could be a hint that you’re at this point. If so, wait until spring or summer to transplant it when it’s growing more vigorously.

Okay, we’ve addressed water, drainage, light, and microclimates. The common thread here is checking in with your plants regularly to be sure they’re in a good place and tweaking the conditions through the year to meet their needs better. A huge benefit of these “well plant visits” is that you’re more likely to find symptoms of insect pest issues before they get out of control. Scroll down for links to past columns on common houseplant afflictions, such as mealybugs, spider mites, scale, fungus gnats, and photos of plants at my house and my sister’s.

I’ve said it before, and I’ll say it again: My houseplants are troopers. Through thick and thin, they greet each day with hope. Hope that Marisa will water them—or stop watering them.

As I scan my motley houseplant collection, each with its own story of how we met and the times I’ve accidentally dropped them, I realize they’re all from 2021 or older.

Do you know what THAT means?!

It means, “See you at the nursery!” I’ll be the one with a huge grin and a new houseplant BFF in my arms.

Links to common houseplant afflictions:

• Managing Mealybugs on Treasured Houseplants - November 05, 2020
• Winterizing Your Houseplants & Patio Plants - November 27, 2017 (mealybugs, spider mites, fungus gnats, etc.)
• Draining or Retaining? Fungus Gnats and Other Side Effects of Poor Drainage - July 12, 2018
• Weeping Fig with the Wintertime Blues - February 04, 2021

HOUSEPLANT PICS

From my sister's house, playing with my niece's dolls:

 

Marisa Y. Thompson, Ph.D., is the Extension Urban Horticulture Specialist and is based at the New Mexico State University Agricultural Science Center at Los Lunas.