2019: HAPPY NEW YEAR!

Does your list of New Year’s Resolutions include paying more attention to your houseplants? Now that the busy holidays are over, we’re almost back to our routines. The plants look forward to returning to their normal locations. They missed those bright windows!

If you’re dissatisfied with your plants’ appearance, today might be a good day to give all the houseplants a thorough examination and a good cleanup.

Philodendron selloum adds a tropical element to the indoor environment.

What Is Wrong With My Houseplants?

Let’s begin with some easily recognized problems:

• the plant has collapsed into a sad-looking heap of wilted foliage
• leaf tips are brown
• leaves are turning yellow
• many of the leaves are dropping off
• the flowers are gone

But your houseplants have sentimental value, so they’re not going into the trash…or into the compost pile. And you know they probably will recover with a little attention. After all, the same thing happened last year.

A home without houseplants looks sterile—to me, anyway—so there will always be indoor plants wherever we live. They rid the air of benzene, formaldehyde, and other pollutants. In return, we get a small boost in the humidity and oxygen content of the air we breathe.

And we enjoy living with nature. Many studies point to the psychological benefits of living with plants at home, at the office, in school, and in the community.

With the renewed interest in growing houseplants, a huge number of species and varieties are available. Popular plants, such as Fiddle-leaf fig (Ficus lyrata), are in such high demand at garden centers that supply is often difficult to maintain.

Several dozen plants are protected here, and will be covered with plastic for the night.

There are hundreds of plants in my collection, from 1″ tall miniature Haworthias to a 6′ tall 40-year-old ponytail palm (Beaucarnea recurvata).

Many succulents and half-hardy perennials spend the winter in the cold frame outdoors, heated with a few strings of miniature incandescent Christmas lights and covered with 2 or 3 sheets of clear plastic (photo, right). There’s just not enough room inside for everyone!

We often have warm winter days in the Carolinas. This gives some houseplants the opportunity to spend a few afternoon hours on the enclosed deck, basking in the mild sunshine.

My Peace Lily Is Wilting

Peace lily, Spathiphyllum.

Wilt in peace lilies due to underwatering is a common problem. There are few plants that exemplify wilt more clearly than this one. A dry but still living peace lily, once watered thoroughly, will recover. But a few leaves might turn yellow, and they won’t green up again.

Peace lily (Spathiphyllum spp.) is commonly available and a good choice for beginning gardeners. You see them in malls and offices all over the country, where lush foliage lends a tropical flair to indoor spaces. Garden centers sell cultivars ranging from robust five-foot-tall specimens to table-top varieties less than 10″ tall.

They like soil that stays lightly moist all the time. But roots that stay wet all the time (from overwatering, overpotting, sitting in a wet saucer, or poorly-drained soil) are unable to “breathe”. Air and water are equally important to root health. Tiny root hairs that absorb moisture rot in wet soil, so the plant can’t get water to the leaves, causing the familiar wilt. A plant can wilt from either dry or constantly wet soil.

Keeping the Peace Lily Tidy

Bird of paradise.

When yellow leaves appear, remove the entire leaf—both the blade (the wide part) and the petiole (the narrow leaf stem). The petiole is connected to the crown, stem, or the main trunk of a plant by a thin layer of cells. That layer of cells, the abscission layer, helps the petiole separate from the main part of the plant if the leaf is no longer useful.

After cutting off most of the yellow leaf, peel off the last bit of the yellow or brown petiole. If it is difficult to remove, as in large cultivars, cut the base of the petiole longitudinally down the center, toward the stem or the crown. Now you can easily peel off each half of the remaining petiole.

This works on other species with strong leaf attachments, such as Bird of paradise (Strelitzia, photo, above), yucca, palm, and dracaena. Removing all those dead fragments greatly improves the plant’s appearance.

Easy to Grow

Peace lilies are not demanding when it comes to light. Provide bright indirect light or morning sun for continuous growth. Disregard the advice that they thrive in “low light”. Sure, they’ll survive for a while, but brighter light toughens the tissues. New growth emerges thicker and stronger.

Plants photosynthesize and grow faster and often bloom in those locations, sometimes emitting a trace of scent soon after the white spathe flowers open. During the shorter days of the year, peace lilies welcome a few hours of direct sun.

Peace lilies in bloom.

When the flower turns brown, snip off most of the stalk, wait a few days, and then pull out the remaining part of the shrinking brown stalk. You could remove it earlier, but sometimes a few green leaves are inadvertently removed at the same time. Once again, this keeps the plant tidy, with no lingering dead remnants.

How Often Should I Water My Peace Lily?

The Environmental Variables

Temperature, light, humidity, fullness of the plant (number of leaves), pot size and type (porous or non-porous), soil composition, and air circulation affect moisture in the soil. A furnace cycling on more often during cold weather necessitates frequent watering of thirsty plants. Knowing how these variables work in conjunction with each other, for each species, will determine how often your plant needs water.

A full and potbound (roots tightly filling the pot) peace lily, in morning sun at 72°F, and in potting soil that drains fast (has a lot of bark chips), for example, might need water every 2 or 3 days. On the other hand, one that was recently transplanted into soil with mostly peat moss and kept in a room at 65°, in indirect light, with 15 other plants nearby (higher humidity) might need water every 5 or 10 days. That’s why it’s so difficult to answer the question, “How often should I water it?”

Most varieties of peace lily are potted into 6″ to 10″ diameter pots. Stick your finger into the soil an inch or two down from the surface. If the surface of the soil feels dry, but there’s damp soil below that, the plant does not need water.

Waiting to water your plants until they begin to wilt is not a good idea. Delaying for only one day could cause another leaf to turn yellow. Or the plant will refuse to produce new foliage.

How Can I Tell When To Water?

A better course of action is to feel the moisture in the soil and the weight of the plant and pot. Eventually, you’ll learn to recognize that when it feels “this” dry or light in weight, it’s time to water. Some gardeners rely on inexpensive soil moisture meters, but I don’t consider them to be very accurate.

And water your peace lily thoroughly! Not just a little bit that moistens the top 2″ of soil. Instead, give it enough to moisten the entire root ball. Some water will drain into the saucer, and a dry pocket of soil might soak up that excess. Drain off any excess that remains in the saucer after 15 minutes.

Many of us conserve energy in winter by keeping the thermostat in the mid to high 60’s F during the daytime and in the low 60’s at night. If you’re growing plants from the tropics, they appreciate being given lukewarm water, about 85° or 90°. This includes ficus, philodendron, pothos, African violet, Alocasia, Aglaonema, and spathiphyllum. Dry soil absorbs lukewarm water more readily than it does cold water.

Upon Careful Examination

Place a fully wilted peace lily in a bucket filled with lightly warmed water up to the pot’s rim. You might have to weigh down the pot. Keep it there for an hour or two, then let it drain. If it doesn’t revive after a few hours, remove the plant from its pot and examine the roots.

Certain materials used at the wholesale nursery, once dry, can resist absorbing water. It’s possible that, even though the plant had been transplanted into better quality potting soil, the plant’s original root ball stayed dry and was unable to produce new roots. When transplanting any plant, tease out some of the roots on the surface of the root ball, especially one that is solidly filled with roots. This helps stimulate the formation of new roots that will quickly grow into fresh potting soil.

I’ve worked on plants that seemed to have moist soil, yet remained in a wilted state. One of these conditions was usually the cause:

• The plant was repotted too deeply, rotting the petioles and the crown of the plant. The crown should remain at soil level, where the green top growth meets the roots. Very few plants survive being planted lower in the soil. Rule of thumb: the original soil surface should be visible after repotting.
• Over time, the organic matter (peat moss, wood products) in soil breaks down and loses most of its volume. Consequently, the soil surface drops lower in the pot. If roots are visible under the crown and are exposed to the air, add fresh potting soil to cover the roots. You might have to remove the plant from the pot and add soil under the roots to raise the crown to the proper level. Either way, don’t bury the crown.
• The roots were not teased out from the root ball, and remained within the tight confines of the original root ball. The root ball dried out before new roots could grow into the moist new soil.
• New potting soil was loosely added around the root ball, and not firmed in next to the roots. Moderate pressure against the roots helps develop a healthy root system, and fills any voids in the pot that could dry out delicate root hairs. It also prevents water from rushing through the pot, following the path of least resistance, and not soaking in.
• The plant’s soil was wet for too long, and the rotted roots couldn’t regrow. Fungal and bacterial pathogens build up in wet soil and cause more problems.
• The temperature in the room or of the water was too low. 
• The plant was overfertilized, burning the roots. Many people think that fertilizing more often or using more than the recommended concentration makes plants grow faster. It doesn’t. Overfertilizing makes plants die faster. High salt concentrations draw water out of the roots, killing them.

Many of the problems we have with houseplants can be avoided if we keep them potbound in the winter. Cooler soil temperatures and shorter days do not favor root growth at this time of the year. It’s better to delay repotting houseplants into larger containers, if they need it, until spring to mid summer.

Headings:

Page 1: What Is Wrong With My Houseplants?, My Peace Lily Is Wilting, How Often Should I Water My Peace Lily? (The Environmental Variables, How Can I Tell When To Water?, Upon Careful Examination)

Page 2: How Often Should I Water Houseplants?, Should I Fertilize My Houseplants?, Brown Tips On Houseplants (Overwatering, Underwatering, Overfertilization, Disease, Guttation, Fluorine), Yellow Leaves, and My Houseplants Are Dropping Leaves

Page 3: Succulents (Porous Pots, Repotting and Refreshing), Ferns (Raise the Humidity), Pothos and Philodendron, Snake Plant (What is CAM?), English Ivy (Spider Mites), Will They Flower Some More?, and Before You Know It

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