Gardening

Taking the Guesswork out of Watering Your Cacti

By Beverly Lehnhardt | Sedona.biz

Do you have a cactus that is just not looking perky? Have you inexplicably caused the long, slow demise of one or more of the prickly plants? Are you unsure about how much water they need, or how often to water them?

Many people have difficulty growing these plants in spite of the fact that they need less attention than other types and it’s surprising how many folks think they never have to water their cacti. All living things need water—some just need more, and more often, than others.

Since over-watering is the easiest way to kill a cactus, the general rule of thumb is to always allow the soil to dry out between waterings—cacti like a nice, deep drink followed by a drying period.  Remember: “Cactus hate wet feet!” Too much moisture in the soil will rot the roots and kill your plant.  To test if your cactus needs water, push a redwood stake into the soil. If it comes up with dirt particles on it, it doesn't need a drink.

Giving your cactus a little bit of water every day is like you standing in a bathtub containing ¼” of water for a month—eventually, your feet would rot!  And use lukewarm water when watering because cold water can shock their roots.

In the summer when daytime temperatures range between 90 and 100 degrees, water your cacti once a week. Watering in the early morning is best, before the sun heats up the ground. Give your cacti a bath, watering the entire plant from the top down and soaking the ground for a deep drink. If you wait until afternoon temperatures are high, the ground will heat up the water and burn the plant's roots, killing the plant.

In spring and fall when temperatures are in the 80s, water cacti once every two weeks; in the winter when daytime temperatures fall to 70 and below, you only need to water once every four to six weeks with less concern about the time of day or baking hot ground temperatures. They take even less water when the humidity is high—for example, during our monsoon season. Aloes and agaves (succulents) do require a bit more water, but don’t overdo it.

For ocotillos, follow the same watering schedule but only mist the branches, letting the water trickle down to moisten the soil. This plant is very drought resistant, requiring little water. Ocotillos are spiny and leafless most of the year, but in response to rain or watering the plants can sprout leaves within three days. The leaves will quickly wither when the soil dries out but the ocotillo can be depended upon to bloom even when there has been little water.

If you are still concerned about the amount and frequency of watering, you can invest $6 to $10 in a water meter and use it each and every time you water. The gauge will tell you how moist the soil is and will take the guesswork out of watering; however, do not leave the meter in the soil—the metal will rust and the meter will eventually quit working.

Cacti do not like highly fertilized soil but on occasion when watering you can use half-strength Miracle Gro or full strength Cactus Juice brand by Sudbury (1-7-6) to boost your plants' wellbeing. The Cactus Juice is formulated especially for cactus at a lower strength than most commercial plant fertilizers.  Also, cactus grow best in a porous alkaline soil.

For good spring flowering, cacti must have cool nights in the fall and winter (35 to 40 degrees). So if you have an indoor cactus and are wondering why it never flowers, place it outside or in a slightly heated garage during the winter months before bringing it back inside. Then watch it flower!

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