Geranium Cuttings Are Turning Black

When to Take Cuttings

• Late winter or early spring cuttings will provide you with plants for the season. Soft wood cuttings are taken from mature geraniums that have begun to sprout. The old geranium can be forced to grow by providing 16 to 18 hours of light and feeding weekly with a houseplant food or regular strength all-purpose plant fertilizer. The extra care forces new green shoots, which are the source of your cuttings. The green, soft terminal ends make the best cuttings. Older, woody growth will root but is prone to rotting.

Water Rooting

• Cuttings are best used fresh. You can take them from any area of the plant, as long as the tissue is green and pliable. Remove a cutting that is at least 3 inches long, using sharp shears that have been sterilized with alcohol or bleach. This will prevent introducing pathogens to the new plant. The cutting may be rooted in a glass of warm water in indirect light. You need to change the water at least daily to prevent the buildup of toxic organisms that could cause the cutting to turn black and die. Once the roots are 1 inch long, the plant can be potted.

Rooting in Pots

• Geranium cuttings have less chance of damping off, getting a disease or being overwatered in a soil-less medium. Sphagnum moss, perlite and sand are useful mediums for rooting the cuttings. Remove the bottom inch of leaves and set the cutting into the soil. Apply moderate water. The cuttings should be kept lightly moist or even on the dry side, but never soggy. Then the pot goes into indirect light where temperatures are ideally 70 to 75 degrees Fahrenheit. Cuttings will root in three to four weeks.

Problems

• The biggest issue with geranium cuttings is excess moisture in the soil and humidity. Either condition combined with the warm temperatures required to cause rooting, can encourage the formation of fungi and bacteria. Botrytis, bacterial blight and a host of other diseases can cause the roots or stem to rot. The rot generally presents as a discoloration or blackening of the plant tissue. Once it begins, there is nothing you can do to save the cutting. It is easy to prevent by minimizing water, enhancing air flow and practicing hygienic cultivation.