Short answer
White, cottony fuzz on a Jade plant (Crassula ovata) is almost always caused by a mealybug infestation. The single most effective fix is to manually remove the pests with a cotton swab dipped in 70% isopropyl alcohol and follow up with an application of horticultural neem oil.
Seeing white, web-like fuzz in the crevices of your Jade plant's stems or leaf junctions is a common sign of mealybugs, which thrive in the low-humidity environments favored by succulents. While early detection makes them easy to manage, these pests multiply rapidly and can weaken your plant if left untreated, so intervention is best performed as soon as you spot the white fluff.
Mealybugs are sap-sucking insects that look like tiny white cotton balls, usually found in the axils of leaves or along the woody stems of Crassula ovata. They weaken the plant by draining its sap and leaving behind a sticky substance called honeydew that can attract secondary fungal issues.
Check: Check the leaf junctions and the undersides of leaves for tiny, white, fuzzy masses that smear when touched.
Fix: Dab each visible bug with a cotton swab soaked in 70% isopropyl alcohol and treat the entire plant with neem oil or insecticidal soap once a week until they are gone.
Because Jade plants are often watered from the top, mineral salts from your tap water can accumulate on the leaves or stems, leaving a white, crusty, or powdery residue. This is not a biological infection but rather a buildup of calcium or magnesium.
Check: The residue will feel hard or gritty rather than soft or fuzzy, and it generally does not move when poked.
Fix: Gently wipe the leaves with a damp cloth using filtered or distilled water, and consider using rain water or distilled water for future care to prevent further buildup.
While rare in dry indoor conditions, Jade plants can occasionally develop powdery mildew if air circulation is extremely poor and humidity levels remain inconsistent. This appears as a dusty, white-gray coating on the surface of the leaves.
Check: The growth looks like a dusting of flour rather than cottony, fuzzy tufts and can be wiped off with a finger.
Fix: Improve air circulation around the plant, move it to a spot with better light, and treat with a mild fungicide or a solution of water and a small amount of baking soda.
When to worry
You should take urgent action when you see the mealybugs spreading to new growth or when the leaves begin to yellow and drop, as this indicates a severe infestation that could kill the plant.
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Diagnose my Jade PlantYes, move the plant away from your other houseplants immediately. Mealybugs can easily crawl to neighboring plants and spread the infestation rapidly.
A mild solution of water and a few drops of unscented dish soap can work for light infestations. However, alcohol is more effective at killing the insects on contact in the tight crevices where they hide.
A white, crusty layer on the top of the soil is usually just mineral buildup from hard water and is generally harmless to the plant. Simply scrape the top layer of soil off and replace it with fresh, well-draining cactus mix.
Consistent with guidance from: University of California Agriculture and Natural Resources, Royal Horticultural Society.