When Houseplants Get Prickly

With things slowing down in the outdoor garden, those of us with the need to keep growing now turn our attention indoors. For indoor gardeners there are few limits if you’ve got that one important element—light, either natural or artificial. Rather than limiting yourself to the same old houseplants, how about some cacti?Too often, indoor gardeners shy away from cacti as houseplants because they think they need to create an indoor desert to grow them. Consider though that not all cacti grow in the desert and our home enviroments can often be perfect for these plants. Yes, cacti have flowers, many flowering in the dead of winter, and a few are quite exotic with intoxicating aromas. Oh, and did I mention how easy they can be to grow?

I doubt if the names chin, bunny ears, rat tail, Turk's cap, Joseph's coat, Irish mist, seven sisters, old man and sea urchin have been rolling off the tip of your tongue lately, but these names are just a few of the more than 1,300 different cacti species that you can grow indoors. Many of them will flower in a bright window in the dead of winter, some with heavenly scents that can only be described as erotically intoxicating (as in the night-blooming cereus).

There are so many myths and misconceptions enveloping cacti that many gardeners are either scared away or confused by them. For example, many people think that all succulents are cacti, and while it is true that all cacti are succulents, all succulents are not cacti. If you understand that, let's go on.

Succulent, as we know, means juicy. Succulent plants usually have fleshy leaves, stems or both. Cacti are just one part of the succulent group and are, almost without exception, plants without leaves. Their bodies are ribbed or flattened and are able to store quantities of water. They are easily recognizable because of their unmistakable stem shape, which can be round, columnar, jointed, fluted, angular or notched. And when they flower, their blooms are magnificent, distinctive and in some cases said to be effective aphrodisiacs.

This is an excellent time to buy cacti, from either a local nursery or garden center, from a mass marketer or by mail, but shy away from those that you may see offered in non-plant stores such as supermarkets and box stores, as the plants’ survival percentages seem to drop precipitously when these cheap (as opposed to inexpensive), small plants of unknown origin are purchased. Do, however, start out small by buying a few small “quality” plants, and don't be concerned if the plants seem much too large for their pots … they like it that way. When I had my greenhouse I had one night-blooming cereus that was 5 feet long with four separate branches" and it was only in a 3-inch clay pot that lay on its side—and it was very happy blooming in the darkness of wintry nights.

Select plants that are sturdy and not in the least shriveled, and that are uniformly colored, nicely balanced in shape and without scars, bangs or nicks. When you get them home, don't rush them to the hottest, sunniest part of the house. Allow them to become acclimated to their new environment by keeping them indirectly lighted for the first few days.

Another misconception is that cacti live and grow in pure sand, require no water and thrive in beastly hot sun. Well, some of them do, but most are really more like "regular" plants than most people realize. They definitely need food, water and light to grow and prefer something more substantial than pure sand (and NEVER beach sand) as a place to set down their roots. And while they can often thrive with soil on the dry side they’ll die quickly when consistently overwatered, especially in plastic pots that don’t let the water evaporate from the root zone.

Just as this is one of the best times to buy cacti, it's also the best time to repot them, especially if you bought one that came in a plastic pot or a pot without a good-sized drainage hole. Select an unglazed clay pot with a large drainage hole for best results, as plastic and glazed pots retain too much moisture, which often leads to wet soil and rotted roots.

Here's a rule of thumb for proper pot selection: For vertical cacti use a pot with a diameter half the height of the plant, one that is deeper than it is wide. For rounded cactus, use a pot that is 2 inches larger in diameter than the plant. For cactus it's important that you use either a brand-new pot or one that has been thoroughly scrubbed with hot, soapy water, then fully rinsed and dried.

Regular potting soil will be too "heavy" for cacti and sand will be to light. Use either a prepared cactus potting soil mixture or make your own, using equal parts of potting soil (Pro-Mix or a peat-lite mix is fine), sand and leaf mold with some small gravel mixed in for increased drainage. Water your cacti only twice a month, no more. It's almost impossible to kill them by withholding water, but very easy to do them in with too much. Always use water at room temperature, as cold showers easily shock and disturb these plants.

You will probably find that your plants may do fine without any feeding, but a diluted feeding during the plants’ growing season and nothing at other times of the year is a pretty safe schedule. Any balanced, liquid plant food should be fine if it’s diluted to half the suggested rate, or use an organic plant food.

Cacti require good light if they are to retain their color, grow and bloom, and part of the thrill of growing these plants is in getting them to bloom … and many are quite spectacular. Put them in the sunniest window you can find and you'll really enjoy these marvelous plants. Some will bloom in winter (those native to the Southern Hemisphere), while others will bloom in our summer or sporadically throughout the year … and yes, there are those that bloom only at night and these tend to have the most incredibly aromatic blooms … but each bloom lasts for only one night.

In the summer the plants can be moved outdoors, but remember they can get sunburn just like us and make sure to bring them back indoors before our first frost. Don’t put cacti outdoors where they’ll be subjected to the constant watering of an irrigation system and don’t leave saucers under the pots that could accumulate standing water.

There is also another world of cacti that are referred to as the epiphytic cacti. This group lives in jungles and absorbs moisture thorough long, tendril-like aerial roots with separate root-like structures that hold the plant in place much like orchids, but absorb very little moisture. This group includes the Christmas, Easter and Thanksgiving cacti which are beginning to bloom now.

Some cacti are obviously hardier than others, such as our local Opuntia compressa or prickly pear cactus, which was once common in the Hamptons but can now be hard to find in the wild. There are even those that survive the winters of South Dakota, so if you are up to the challenge of growing hardy cacti try these: Coryphantha vivapara, Echinocereus viridiflorus, Noebesseya missouriensis, Opuntia compressa, Polyacantha, Aurea, Fragilis, Rutila and Humifusa.

All cacti can be grown from seed, unless they are the grafted types, and many seed catalogs and specialty mail order growers offer seed. It's another one of the great horticultural challenges to get many of the species to germinate, but if you've got a few months to a few years to wait, give it a shot. Keep growing.

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