Intrepid Indoor Gardening

Handle Cactus With Care

Though our maritime Northwest winter are short, there are still many days when getting out into the garden is challenging if not dispiriting. When feeling garden deprived, it’s very easy to yield to the temptation to bring in pots of blooming whatever. Some, like hyacinths and hydrangeas, are very easy to cope with once their flowers have faded. Others, notably cactus, can present more of a challenge, especially as the seasons roll by.

I was recently asked how to repot an indoor cactus now over six feet high and falling out of its pot. Having repotted a huge cactus once myself (a memorable experience), I was able to explain that, although for the most part, one proceeds as when repotting any large plant, foam pipe insulation is the cactus grower’s best pal. Just as it protects prickly roses by insulating their stems in cold winters, thicker chunks of larger foam pipe insulation can protect YOU if fit snugly over a spiny cactus.

Proceed With Caution

If your cactus is really huge, get the biggest foam insulation you can find and cut it in half lengthwise. Tape as many sections as you need to reach around the big stems with duct tape. Now wrap it strategically around the stems with more duct tape. Don’t put duct tape on the cactus; keep it on the foam.

Place the most foam where you will be touching the plant. If the cactus has very long thorns, you might need two layers of foam in a few places so you can lift the rootball  without puncturing your hands. The foam doesn’t need to cover the whole thing, but do be generous. When a stray stem grazes your shoulder or face (as it invariably will) , you’ll be glad those brutal prickles are swathed in foam.

Reducing Collateral Damage

I used to be quite casual about such projects, but have learned that a little prep greatly reduces the aftermath. Before unpotting any large plant indoors, cover the floor with an old shower curtain. Have the new pot ready at hand, along with the fresh potting soil. If the new pot is really big (needing most or all of a big bag of potting mix to fill it), add some charcoal (the horticultural kind or the stuff used in fish tank filters) to the bottom half of the soil to keep it sweet.

If the plant is pot bound, set it on its side (on the drop cloth) while you gently loosen the winding roots. Place the freed roots in their new home, then gently but firmly pack in the fresh soil around them. You might need a friend to hold a large plant upright while you firm in the new soil. You may also want to stake your tall plant with slim bamboo rods and raffia to keep it upright until those roots take hold in the fresh soil mix. Water it well with luke warm water to reduce shock to newly teased-open roots. Don’t feed or fertilize for at least a month after repotting to give the broken roots time to heal.

Planting As The Seasons Swing

In general, repotting is best done before the middle of December or at the tail end of winter, since even houseplants respond to the slowing of the year. Unless your houseplants are living under lights and in heated conditions, they’ll prefer not to have roots disturbed in winter. I usually avoid repotting until about mid February, or whenever the first snowdrops arrive. However, when a plant falls out of its pot or otherwise requires immediate assistance, it’s better to repot than wait.

Winter repotting is most successful when we reduce as many stresses as possible. No indoor plant really enjoys the direct light of a south or west facing window, and a convalescent one least of all. Most flowering houseplants prefer indirect but bright light, such as that from an east or north facing window. Let your newly repotted plant become slightly dry before watering again. Gently poke a finger in the soil to check for moisture before watering. The top inch of soil should be fairly dry between waterings.

Helping Plants Heal

When you can see signs of active growth, you can resume feeding. As with any houseplants, feed transplants with commercial house plant food about once a month, all year round. Always dilute the fertilizer to half the strength suggested on the label, adding some liquid kelp (a tablespoon per gallon of water/fertilizer mix) from March through September. Always water plants before a feeding, letting each pot drain for at least 10 minutes. Empty the saucer of excess water, then apply the food; otherwise fertilizers can burn both leaves and roots badly. Good luck!

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