White Balls in Soil: What They Are and What to Do About Them

Discovering small white balls in the soil of your houseplants or garden can be an unexpected and puzzling event. For many plant owners, this sight raises immediate questions about the health of their plant and its soil environment. These tiny spheres can originate from several sources, ranging from beneficial additives to signs of unwelcome pests. Understanding what they are is the first step toward taking the correct action, or correctly taking no action at all.

Identifying the White Balls

The identity of these white specks often lies in their texture, shape, and distribution within the soil. One of the most common sources is perlite, a type of volcanic glass that is heated until it puffs up, creating a lightweight, porous material. Visually, perlite pieces resemble tiny, irregular fragments of white styrofoam and are mixed into potting soil to improve aeration and drainage.

Another frequent discovery is slow-release fertilizer pellets. These are uniform, perfectly spherical beads that may be white, cream, yellow, or even blue. Designed by soil producers to provide a steady supply of nutrients over several months, these prills are scattered throughout the potting mix.

A less uniform finding is mycelium, which is the vegetative network of a fungus. While it can appear as a web-like or fuzzy white substance on the soil, it can also form into small, fuzzy balls. This growth is a natural part of decomposition in organic-rich soil and is often a sign of a healthy, active soil ecosystem.

Finally, the white balls could be pest eggs. Slugs and snails lay clusters of translucent, off-white, or jelly-like spheres that are about 3mm in diameter. Another possibility is the eggs of root mealybugs, which are often hidden within a cottony, waxy mass near the plant’s root ball.

Differentiating Harmless Additives from Harmful Pests

A hands-on examination can distinguish between benign soil amendments and a potential pest problem. The “crush test” is an effective diagnostic: pick one of the white balls from the soil and press it between your fingers. Perlite, being a brittle mineral, will crumble easily into a chalky white powder. A slow-release fertilizer pellet will feel much harder and will crack under firm pressure, sometimes releasing a small amount of liquid or powdered fertilizer.

Fungal mycelium, being soft and web-like, will not crumble or crack; it will simply smear or flatten. Pest eggs, in contrast, will have a distinctly different feel. They will be soft, and crushing them will cause them to “pop” and release a watery or mushy substance.

The location and distribution of the balls also provide important clues. Perlite and fertilizer are incorporated into potting mix during production, so they will be found distributed evenly throughout the entire pot. Conversely, pest eggs from slugs, snails, or root mealybugs are almost always laid in concentrated clusters just under the soil surface, against the side of the pot, or nestled in the plant’s root ball.

Observing the overall health of your plant can offer additional context. If your plant is green, growing well, and shows no signs of distress, the white particles are very likely harmless perlite or fertilizer. If the plant is yellowing, wilting, or its growth is stunted, investigate more closely for pests, as these symptoms can indicate an underlying infestation.

What to Do About White Balls in Soil

If your investigation reveals the particles are perlite or slow-release fertilizer, no action is necessary. These are beneficial components of your potting mix and should be left undisturbed.

If you determine the substance is mycelium, it is harmless and can be left alone. Its presence indicates the soil is rich in organic material and has a healthy microbiome. However, extensive fungal growth can suggest that the soil is staying consistently too wet, which could create conditions for root rot. Consider assessing your watering routine to ensure the top inch or two of soil is drying out between waterings.

If you confirm the presence of pest eggs, prompt action is needed to protect your plant. The first step is to physically remove any visible egg clusters you can find. For a more thorough treatment, a hydrogen peroxide drench can be effective at killing remaining eggs and larvae in the soil.

A safe mixture is one part 3% hydrogen peroxide to four parts water. Water the plant thoroughly with this solution when the soil is dry.

For a severe infestation, the most reliable solution is to repot the plant entirely. Gently remove the plant from its pot and wash the old, infested soil from the roots. After cleaning the pot with soap and water, repot the plant using fresh, sterile potting mix to provide a clean environment.