Repotting Houseplants

Houseplants on the Windowsill

By Amy McDowell

Houseplant is such an ordinary name for something really wonderful. They are one of the delights that sustain my itch to garden in winter. My favorites are the philodendrons, and I have a collection of ten different kinds. There are hundreds of species of philodendrons, from tiny vines with thumbnail-size leaves to climbing monsters that can cover a home in a tropical environment.

There are two main reasons I dearly love philodendrons. I love the way the new leaves emerge and uncurl. That tender new growth reaching out reminds me of spring. And best of all, philodendrons are rarely targeted by insects. I have never had insects on my philodendrons, although some of my other houseplants get to be a mess with pests.

This is the time of year I work on repotting. With only mountains of catalogs, books, and magazines to keep me occupied, I enjoy working my hands into the potting soil.

Most houseplants are happiest when their roots are somewhat snug in their pots, but it is a good idea to slip the root ball out of the pot annually to take a look. I generally repot a plant once every three to five years.

The standard rule of thumb is to only go one pot size larger when repotting. If you transplant into a much larger pot, the plant sits in the center of all that new soil and struggles to overcome the transplant shock. The excess soil surrounding the roots holds too much moisture, and that can lead to root rot.

Many gift plants come in decorative sleeves that don’t drain. You’ve got to toss the sleeves right into the wastebasket and give your plant a pot with good drainage and a saucer underneath so you can dump out the excess water. The pot doesn’t have to be fancy—a healthy houseplant will become the focal point and a plain plastic pot will fade into the background.

Tending to houseplants is one of winter’s joys. With a little care, your windowsill garden can carry your spirit through until spring.

One born every minute

Suckering trees and shrubs

By Amy McDowell

In horticulture, there’s one born every minute. And there I was in the front yard in the chilly knee-deep February snow, pruning the suckers from around the base of my spring snow crabapple. I had read that if you prune suckers during the winter months they don’t grow back as quickly.

As the weather warmed in spring, tiny red buds emerged at the base of the trunk, and soon enough skinny suckers were growing up at the base of the tree again. Exasperated, I realized I’d been had—the only thing that had delayed the new shoots was winter.

Suckers are not all bad. Most of my favorite shrubs have a suckering habit that results in a broad mound of growth and a beautiful shape when mature. There are a great number of suckering shrubs, including lilacs (Syringa species), Hydrangeas, Spireas, pussy willow (Salix discolor), serviceberry (Amelanchier arborea) and bottlebrush buckeye (Aesculus parviflora). Many of these form dense thickets that create wonderful privacy when used as hedges. Frequently, you can dig the suckers from around the base of the original plant and use them to extend plantings around the garden.

Staghorn sumacs (Rhus typhena) ablaze in red and orange right now, and elderberry (Sambucus canadensis) sucker to form large, open colonies. Both are fairly aggressive for a small garden, but regular lawn mowing at the edge of the colony is all that’s needed to fight back their spread.

Suckers are a sign of a plant’s genetic vigor. A non-suckering shrub like purple-leaf sand cherry (Prunus cistena) can fall prey to collar rot in heavy clay soil, but if it had the ability to sucker, young new stems would keep the shrub alive as the older stems succumbed. If sand cherries suckered, it would vastly improve their durability and longevity in central Iowa landscapes.

Despite all of the great suckering plants out there, it’s still tough to come up with an advantage to the raggedy suckers at the bases of crabapple trees. Tender rabbit fodder, I guess, to slow their attacks on the tasty trunk bark.

You don't always have to plant in drifts

Rebel against the rules of gardening

By Amy McDowell

“Welcome to Plant Collectors Anonymous” announced the crinkled paper sign on the door. One edge was smudged with what looked like a dirty thumb print. A ring of beige metal folding chairs sat in the middle of the room, cold on my tush as I took a seat. Before long, the circle filled and latecomers had to dash to another room and clumsily drag in a few more chairs. The gardeners were a motley crew—young and old, tailored and frumpy. They sat and smiled awkwardly at one another, hands in their laps carefully twisted to hide the dirt that was, without exception, under their fingernails.

And the confessions began. One after another, each gardener rose and gave his or her first name, followed by that aching mantra, “and I’m a plant collector.” Oh! The shame! Would we ever conquer our collecting ways and plant properly, that is, in drifts? It was embarrassing, for sure. In our rambling plant passion we bought what we loved and we loved whatever little beauty caught our fancy on our many, many garden center junkets. Our gardens, packed with a hodgepodge of plants, wantonly violated the rules of good garden design.

It wasn’t until I heard Tony Avent speak at the Western Nursery and Landscape Association that I shook off my shame and proudly, defiantly, lifted my chin. Tony owns Plant Delights Nursery in Raleigh, NC, and confessed that he grows thousands of different plants at his home. And no two are the same. None. No plants in masses or odd-numbered drifts. Onesies everywhere. And he showed slides to prove it. Slides of a gorgeous garden.

“I admit it, I’m a plant collector,” he said. And then he said if we think plant collecting is bad, our whole value system is screwed up. “What gets people more excited than plants?” he asked. They grow bigger and more beautiful and you can divide them and share them with your friends. You can’t do that if you collect antiques, he says. Then he even trumped the old “you shouldn’t buy a plant unless you know where it’s gonna go” nag with a sharp, succinct, “What kinda crap is that?”

Aaah. Now that’s my kinda guy. Let loose the “should” and “shouldn’t” gardening rules and have fun again. Like when I was a girl of seven in my favorite Bugs Bunny jeans planting marigolds. (Before I learned that growing marigolds is taboo or amateurish or just not done.) Back to when I planted my first Clematis and delighted in every leafy tendril, every bud and, as they opened, every bloom.

Whoever made up the rules needs to learn to love gardening again. And the rest of us need to learn to follow our passion and forget the restrictive rules for gardening. I’m thrilled that I have the audacity to say this with pride: “My name is Amy, and I’m a plant collector.”

Oooh, that awful dry air in winter!

Houseplants and humidity

By Amy McDowell

When I was in charge of watering inside the dome at the Des Moines Botanical Center, I watered more than just the plants. I also soaked the concrete walls and pebbled paths. The plants, screaming for moisture, needed more than just a drink of water—they needed high humidity like the tropical rainforests of their origins.

During these cold winter months, the dry outside air is sucked into our furnaces, heated, and pumped through the heat vents throughout our homes. And just as we suffer with dehydration such as thirst, dry, itchy skin, tired, burning eyes and tender sinuses, our houseplants are suffering with dehydration that shows itself as curling leaves, dry brown leaf tips, yellow leaf margins, shriveling, wilting, bud drop and limp, weak growth.

The water that houseplants take up through their roots is used for growth, but much of the moisture is released, or transpired, through tiny holes in the stems and leaves called stomata. Winter air pumped through our furnaces is so dry that it rapidly taxes houseplants beyond their capacity. There are a number of things you can do to raise the humidity level and aid plants, and it doesn’t even require watering your walls and floors.

·        Humidifiers are the simplest and most effective method to raise humidity.

·        Group plants close together so they can benefit from each other’s transpired moisture.

·        Make pebble trays. Fill sturdy plant saucers with pebbles and water and place them around your houseplants. The pebbles create more surface area than just a dish of water so it will evaporate quickly.

·        Turn down the furnace. Plants will transpire less moisture if the furnace isn’t running as often. Also, keep plants away from heat vents and drafts.

·        If the kitchen or bathroom is bright enough, move plants there, where humidity is often higher than the rest of the house.

·        Misting plants is the least effective option. It is a short-term, temporary solution that must be repeated frequently throughout the day to even make a difference. In addition, water droplets on the leaves may lead to disease.