Are Grubs Bad For Potted Plants? (Gardeners Thoughts)

It’s disgusting.

You look at those white, wriggly insects in your potted plant. It’s grubs, but you’re not sure if they are good or bad for the plant.

Grubs are bad for potted plants because they feed on the plant roots and damage them. The grubs grow into beetles that eat plant leaves and stems causing more damage. You can hand pick grubs from the soil and put them in soapy water.

But why are white grubs in pots so bad, and how can you solve the problem? Let’s look at how to keep your potted plants safe from grubs.

How do grubs harm potted plants?

White grubs in pots damage plants by eating their roots. Damage to a plant’s root system can cause dire consequences no matter what the plant’s location. Without adequate roots, a plant will usually die of malnutrition fairly quickly.

Grubs are especially dangerous though, as plants that survive the original onslaught will then often face beetles that can cause even more damage to the plant’s leaves and stems. This one-two punch can be incredibly difficult to survive for any plant no matter how tough it is.

In a garden, this problem might take a while to become apparent, since we usually find grubs only underground and tend to take effect fairly slowly. This is the same as it is in an indoor environment, except that it’s even more important that you catch an indoor grub infestation quickly than it is to catch an outdoor one.

Grubs are the larvae of different species of beetles that feed on the organic matter in the soil, plant roots and foliage. Thus, causing the plant to wilt and decay. Moreover, grubs can especially be a problem during the winters since they can hide away at the base of the plant and come out during the spring. Hence, it’s advisable to keep turning and aerating the soil of pots after every season. – Karan Mahajan, Co-Founder, All That Grows

Not only will the plant in the pot likely be the only thing that the grubs are eating, but once the grubs grow up into beetles, they become serious pests that can cause a lot of damage to your home.

Depending on the beetle the grubs grow into, they might even cause structural damage to important parts of your home. Wood-boring beetles and powder-post beetles can both cause damage to everything from furniture to your home’s support beams.

This all makes it very important to spot a grub infestation before it becomes a more serious problem.

How to get rid of grubs from potted plants?

Your first instinct might be to use chemical insecticides to deal with the pests, but for several reasons, this will probably backfire on you.

The first reason is that insecticides can cause damage to the plants that they’re meant to protect, and the second and more important problem is that despite the name insecticides are dangerous to pretty much all animal life including people.

Fortunately, there are several non-poison-based products you can purchase and apply that should be able to help ease the grub problem.

Grubs usually feed on plant roots and can cause severe and irreversible damage to the vegetation. If there are a lot of them, then yes, they are damaging the plants. Unlike the earthworms that fertilise the soil, grubs end up ruining the plants by munching on the roots. – Vinayak Garg, Founder, Lazy Gardener

The first biological insecticide that you’ll want to look at is helpful nematodes, certain kinds of which will eat grubs and not damage your plant at all.

Milky Spore is another biological agent which should be able to wipe out your grub population, as it is a bacterial pathogen that specifically targets beetles and grubs and is almost always deadly.

If you’re not afraid of damaging the plant, you can also simply get rid of the grubby dirt (carefully, as grubs are just as bad for lawns as they are for potted plants and gardens) and replace it with new soil that has been pasteurized. As long as you cleanse the pot, this should be a foolproof way to get rid of all the grubs in it.

How to prevent grubs in potted plants?

The best way to prevent a grub infestation in a potted plant is to be very careful about the soil that you put into the pot.

Since you have pretty much complete control over what soil you use, as long as you make sure that whatever products you use in the soil have been treated for pests it should be pretty rare for you to end up with unwanted creatures in your potted plant’s soil.

You can also treat your outdoor spaces with grub prevention products, which should provide an extra layer of defense against grubs in pot plants.

How to find out about a grub infestation?

The easiest way to figure out that you have a grub infestation is to monitor your potting soil. This is easier said than done though, as unless you’re frequently digging around in your plant’s pot, you’re really unlikely to find where the grubs are living.

Fortunately, there are other signs of a grub infestation that might be a little easier to spot if you’re looking for them. You can also tell a grub infestation by its effects (namely dying plants and an increasing number of beetles in your home).

But by the time you’re experiencing these symptoms, the problem has usually progressed beyond the point where solving the problem will be simple.

Grubs are voracious pests that attack your plants by feeding on the roots. Grubs quickly turn into adult beetles that can eat your other prized plants’ leaves. If you notice that moles, skunks, and birds are enthusiastically digging through your garden pots, you’re probably dealing with grubs. There’s no time to lose – get rid of them before they or their hungry predators damage your precious plants. – Gena Lorainne, Fantastic Services

If the plant is outdoors, grubs will attract an increased number of scavenging animals like raccoons or crows. These can smell grubs in soil and will dig through most soil to get to them, which makes them a clear sign of an infestation. Unfortunately, they can cause their own additional damage to your plants, making it even more important to solve the grub problem quickly.

Unless you have a pet raccoon, however, this is unlikely to help you if your potted plant is indoors, as most potted plants are. In this case, the best way to check for grubs is to test for them.

One fairly reliable test you can do is to put a strip of cardboard over the top of half of the soil and to water only the other half.

If there are grubs in the pot, the ones in the dry part of the soil will come to the surface to find water and be convinced by the cardboard covering that they are still underground.

This test is worth reforming if you suspect you might have a grub problem for any reason.