How to Care for Senita Cactus With Frost Damage

Inspect the cactus for damage after the frost and do not do anything to the plant until the threat of any further frosts ends for the season.

Cut away any blackened, dry and crisp portions that are apparent after two weeks only it they bother you. Leaving these areas on the plant do not harm it. With growth in time, the damage is less noticeable. Use a fine-toothed pruning saw or sharp, clean garden knife.

Prune back any limp, yellow and waterlogged-looking cactus portions, as these are dead tissues that cannot recover and will continue decaying. Cut back healthy, live tissue or take the entire stalk down to the crown, if necessary.

Cover the cactus with a cotton sheet on nights forecast for near freezing temperature. Additionally, add a lit 60-watt bulb under the sheet boosting ambient temperatures. Keeping the bulb from touching any portion of the plant prevents burns. Move any container-grown senitas indoors at night when frost is possible.

Prevent repeated frost damage by building a wall structure near the plant or placing the plant near a patio that radiates heat during the night.

Refrain from overwatering a frost-damaged senita cactus, as this compounds their troubles. Feel the soil 2 to 3 inches down before each watering. If the planting medium feels at all moist, do not add water. If the medium feels dry to the touch, then irrigate it. Follow the general guideline for watering the cactus with no greater frequency than every 10 to 14 days. If growing in clay, watering-holding soil, it may be less frequent; in very fast-draining sand, it may be slightly more frequent. Use touch to determine what is appropriate for your planting location.