TheMondayGarden.com

How much do plants raise your humidity? One African violet in a 3-inch pot isn’t going to make much of a difference as it only uses a few ounces of water a week. Five large plants in 12-inch pots that collectively need a gallon a week will make a noticeable difference. The more water your plants use, the more moisture they release into the air. You can get more moisture into the air via the house plants by increasing the number of plants, by choosing larger plants, and by pampering your plants with humidity raising techniques that pamper the home’s human residents as well. You can also choose water-loving plants. Without turning your house into a jungle, you can use plants to get your humidity levels up to around 30%.

Watering- the general rules: By now, you’ve probably figured out the connection between giving your plants more water and more water getting into the air. This, however, is not a license to drown the plants. Rot from over-watering is the number one killer of house plants.

Most plants need to get a bit dry between waterings so the roots can get enough air. Before you water, the soil should be dry to the touch down a 1/2 inch in small pots (1 to 5 inches in diameter) and up to a full inch in large ones. When you water, you should water until you see water coming out of the bottom of the pot. By making sure that you hydrate all of the soil, you encourage the roots to fill the whole pot – not just the top few inches.

Don’t let the plant stand in water after watering. Drain off the excess water. A turkey baster works well. Alternatively, put drainage material such as pebble in the plant’s saucer to keep the plant’s base above the water level. Most plants grow less in winter so want a little less water than they use in summer.

Pot size: You’ve probably also figured out the connection between bigger plant pots that hold more soil, and thus more water, and more water getting into the air. Again, don’t over do it. Moving a plant directly from a 3-inch pot into a 10 inch one will probably just kill the plant.

As a general rule, a plant should be in a pot that is small enough so that the soil dries out enough to require watering at least weekly. A larger pot encourages rot. If the plant requires watering more than twice a week, it probably is drying out too quickly and needs a bigger pot. When increasing pot size, it’s very risky to increase more than 1 to 2 inches in diameter at a time. (Use only a fresh, sterilized potting mix made specifically for house plants.)

Humidity raising techniques. There are a number of things you can do for your plants to raise their humidity and, thus, yours. The gardener’s favorite trick is to put a couple of inch of drainage material, like pebbles, under the plant so you can add extra water to evaporate during the week. Another favorite trick is to put an inch or so of moss on top of the plant’s soil and wet the moss (but not the soil) every day or so. This works much better than misting as it takes much longer for the water to fully evaporate. (Misting is a bit of help too if done regularly). Terra cotta (clay) pots let the soil breathe, so they dry out more quickly, releasing more moisture into the air than plastic pots. Grouping the plants also helps.

THE HUMIDIFIERS

General culture and sources: The following plants will all help you raise humidity in one fashion or another. Unless otherwise noted, these plants are all readily available from local plant outlets, generally pest-free, and will do well in the house in medium to low light (i.e. no direct sun required). Many of these plants, and most of your other house plants, for that matter, are chlorine sensitive so leave their water out overnight before using.

Moisture-loving plants: Some plants prefer that their soil be kept “evenly moist”, rather than drying out a bit between watering. These plants will use more water weekly than plants that need to get a bit dry between waterings.

Peace Lilly and Chinese Evergreen: The toughest, easiest to obtain “evenly moist” plants for the house are the peace lily (Spathiphyllum) and its kin the Chinese evergreen (Aglaonema). Both types of plants come from the arum family, and are the only plants on both my “low-light/easy” list and the best indoor flowering list. The plants need medium light and occasionally fertilizing to flower reliably. They will suffer if allowed to get too dry.

Ferns: Ferns are also tough, reliable house plant that prefer lower light and like their soil kept evenly moist. The Boston fern family (Nephrolepis) are the all-time easiest ferns for the housel . They do, however, like to be watered a bit less in the winter. Table ferns (Pteris) are often found in the foliage plant section at the local plant outlets but can be fussier. Many ferns are chlorine sensitive. Some ferns will not thrive in household humidity levels or prefer temperatures in the 60F range. Most ferns do not like direct sun. .

Prayer plants and other Marantas: The prayer plant family (Marantas) are lovely, readily-available foliage plants with multi-colored leaves that like “evenly moist” conditions. They are a bit tough to grow as they will slowly die if exposed to chlorine on a regularly bases and need to be kept on the dry side when in their dormant phase. They prefer warmer temperatures (70F or better), higher humidity, and strong light but no sun. Their colors will glow if you give them a weekly bath. When unhappy, Marantas are subject to spider mites, mealy bugs, and rot. Should this occur, toss the plant and choose another one more suitable for your growing conditions.

Coralberry: Coralberry (Ardisia) is a fantastic little tropical tree that grows happily indoors in low to medium light as long as it gets enough water. It has tiny white flowers in spring and eye-catching red berries most of the year. It does take coralberry a few years to get the flowering age but the tree will live a long time. If you want to keep your tree fairly small, cut it back hard every few years just as it starts to grow in spring. Small coralberries some times show up in local plant outlets on the foliage table. Look for a clump of tiny trees with dark greens shiny leaves, like a coffee plant. The coralberry, though, has a scalloped leaf edge. You can also buy coralberry plants on-line.

Hydro-culture: Many plants can be grown for years at a time directly in water. Use a wide-mouth vase to increase water surface area and thus weekly water evaporation. Change the water frequently to prevent bacteria build up. Among the plants best suited for water-culture are golden pothos (Scindapsus) and its philodendron kin, arrowhead vine (Syngonium), and wandering jew (Tradescantia). Ironically, if you are growing these plants in soil, they like to be watered only when dry.

“Lucky Bamboo” “(actually a Dracaena) is commonly sold by the stalk to grow in water. Like the ferns and marantas, lucky bamboo is especially chlorine-sensitive.

Bog plants: Bog plants grow with their feet, but not their root crowns, in water. Graceful, easy papyrus (cyperus alternifolius) is the all-time number one indoor humidifier plant. Papyrus is a member of the grass family, famous for having been used to make paper in ancient Egypt.

I have two papyrus plants in 10” plastic nursery pots sunk in water-proof pickle crocks sitting in my den on the under-window radiator. In the winter, the plants use at least one to two gallons of water a piece, while providing green-munchies and play toys for the cat, and acting as an attractive window screen. What more could you want from a plant?

Papyrus are bog plants so the bottom third of the pot should be underwater at all times. Do not cover the plant’s crown in water (it’s not a fish!) and don’t let the plant dry out completely. Papyrus are happy in low to medium light; they like sun but can burn with too much. Mist in winter to discourage spider mites.

A good place to buy a papyrus is your local tropical fish store where they’re sold for use in fish tanks. You can also buy them on-line. Local nurseries may also carry them from time-to-time. Generally, the available plants will be small (1- to 3-inch pot; leaf stalk about a foot high). You can turn this little plant into a good size one by giving the plant good light and by increasing the pot size an inch or tso every 2 to 3 months until the plant is a big as you’d like. Mine are about 3 feet tall but if you really work at it, you can get them to grow up to around 5 feet.

Picture: arrowhead vine

Note to Connecticut readers: A version of this article appeared in the first issue of Stamford Plus, in December 2005

Photo credits: Sue Sweeney

© Sue Sweeney 2005