Spider Mites: The Creepy Crawlies in Your Garden That Cause Damage
There is a fear that every gardener has. It is always in the back of our minds, like a horror film you can’t forget because it seems so possibly real. Halloween only comes once a year, but in a garden, the creepy crawlies are a constant source of anxiety. Protecting your plants from pests, and trying to get rid of them if they do show up is a stressor that every gardener knows.
Today, we’re going to talk about one of the most insidious little monsters that can really take over your plants and spread like a plague. Little arachnoid creeps with a thing for web construction and sucking the life out of your plant: spider mites.
Spider mites colonize and build webs on plants.
What are Spider Mites and how can you recognize them?
Spider mites are so called not just for their proclivities for web spinning. They are in fact arachnids, just like spiders, though they are of the family Tetranychidae. They feed on the leaves of plants (any green plant will do, though some species are more prone to certain plant groups), and if not checked, can quickly multiply to an infestation.
Available in a variety of colors from bright red to brown, yellow or green, spider mites live in colonies, usually on the underside of leaves. They are small enough to look just like tiny dots to the naked eye, but any simple magnifier will reveal their oval bodies and eight legs. Most species have dark spots near the head, and several have spot patterns on the body as well. Not every species of spider mite spins, but most do, and this makes them easily distinguishable. Spider mite eggs appear as clear little drops on leaves that turn an amber color when about to hatch.
Spider mites are very small, seeming just the tiniest of spots on your leaves, so it’s always a good idea to have a magnifier on hand. A jeweler’s loupe is well favored among growers for thorough inspection of plants and for spotting and identifying pests.
Two-spotted spider mites and their eggs.
Plants that are being ravaged by spider mites will first show evidence of injury from these pests in little discolored (usually whiteish) splotches where the spider mites have been feeding on the leaves. As their numbers increase and they continue to suck the sap and nutrients from the leaves, you will notice brown, curled edges as the nutrients in the leaf are depleted. As numbers increase, most spider mite species will start spinning webs around the plants. If left unchecked, they can ruin whole crops.
Early stage spider mite damage in leaf.
Significant spider mite damage.
How do you keep Spider Mites out of your garden?
The first three rules of any pest control are:
If pests don’t have the opportunity to enter your garden, they can’t infest your plants.
Spider mites especially are very good at attaching to clothing, so a good practice is to have a layer of clothing you only wear in your garden. Even shoes should be left at the door after visiting your garden. It is worth bearing in mind that trips to the garden supply store can also bring these pests home with you, so be sure to change your clothes before getting near your plants. One thing that is a little more delicate, and something we don’t really like to think about, is our friends who are gardeners. If you have grower friends who come over to your house or you go to theirs, be very aware of what is touched, make sure you change your clothes after, and make sure your friends are not entering your garden in clothes they wore around their own garden.
Your equipment can carry the mites and eggs of mites, too. Be sure you are cleaning your scissors, gloves, shears, stakes, and any other piece of equipment you take into the garden. Anything that comes into contact with the plants should be cleaned and scrutinized.
A very good practice for gardeners is quarantining. When you have new starts or plants coming into your garden, keep them away from your main growing area until you have made a very close inspection and given them a clean bill of health. New plants and new genetics are exciting, but the last thing you want is to bring in some outside influence that will bring down all your plants because you didn’t take that extra precaution.
Mixing Neem seed oil or Neem cake in your soil medium is a great way to preempt any soil-born pests such as fungus gnats, but spider mites lay their eggs on the leaves of the plant, so while Neem is a good idea in general, its effectiveness against these particular buggers is limited.
Mites in general, including spider mites, thrive in dry, dusty environments, so keeping your plants watered and clean is important as well. You don’t want to overwater your plants, of course, but maintaining a consistent moisture will drastically reduce the presence of spider mites. Cleaning your grow space and plants is important as well. If growing in a greenhouse or outdoors, spray down walkways and surrounding soil with water to reduce the possibility of kicking up dust. An occasional light spray on leaves with water will also reduce dust. Be sure to get the underside of the leaves, where the spider mites live.
Spider mites on underside of leaf.
Spray your plants clean every few weeks.
What if you have Spider Mites in your garden?
If you find evidence of spider mites in your garden, the time has come to buckle down and take action. For leaf-borne pests such as these, we recommend starting a spray regimen.
We have found that Lost Coast Plant Therapy is a great natural product for attacking spider mites and fungus gnats in your garden. Our gardeners have had great success with the product and we love their simple, natural ingredients. Spray your plants every day for about a week to get rid of the little terrors. Again, pay special attention to the underside of leaves where the colonies gather.
Spider mites and other pests thrive in warmer environments. When treating for these pests, bring the temperature of your garden down to 70 degrees Fahrenheit (21 degrees Celsius) or less to slow down the activity and reproduction of the pests.
Introducing natural predators is always a good idea as well. There’s a certain kind of ladybug with a black carapace that specializes in hunting down and eating spider mites called the spider mite destroyer. Predator mites can also be very effective if you are growing indoors or in a fairly humid environment. Check with your supplier before you buy predators, to be sure your environment will support them.
It is important to note that while spraying is effective in combating living mites, Their eggs can take 3-5 days to hatch, so continuing the regimen of spraying even after you see the creepers dying off is important.
Stethorus punctillum, the spider mite destroyer.
When Spider Mites get out of control, what should you do?
Spider mites are very small and easy to miss. Some of them are bright red or brown, but they can also be yellow or green, which makes them hard to spot. So it’s not uncommon for a pretty good number of them to spring up before they are noticed in a garden.
If you have a heavier infestation, we suggest getting into a diversified spray regimen, spraying with one pesticide one day, and another the next day, switching back on a daily rotation for a couple weeks. Don’t mix two different compounds in one spray; use the different sprays on different days to prevent the pests from possibly developing resistances to a single compound.
Spider mite infestation.
Sticking with natural pesticides is an important practice as well. Chemical pesticides have a tendency to kill off the natural predators of spider mites. Here’s a list of good products our grow gurus have compiled:
The Spider Mites are Gone…? Or are They?
Spider mites can remain dormant in leaf litter and debris for months. In temperate climates in nature, the life cycle of the spider mite accounts for colder months with an ability of the females, who are larger and more hardy than the males, to go into stasis, clinging to the leaf litter. When spring comes around, the warmth brings the spider mites back to consciousness, and they climb back up and lay their eggs on the leaves again.
If you have a loose composting layer on top of your soil, you may want to remove that layer entirely. Stay vigilant after you have taken action against the spider mites. Use whatever magnifier you have to make a close inspection of the ground below the affected plants. Because they can remain dormant for months on end, lowering the temperatures in your garden will only slow their feeding and propagation; it will not kill them off.
Constant vigilance is the key once you have eliminated any sign of the spider mites that were in your garden. Double down on cleanliness of yourself, your garden, and your tools. keep a close eye on the ground, the stalks, and undersides of leaves. If you keep up your game, you will keep the mites at bay.
Live a Spider Mite free life!
Now that you have gained knowledge and skills to overcome these pests, you can officially count yourself among the ranks of the mitey avengers! You are a true savior of plants everywhere.
Whatever you are growing in a closet, tent, greenhouse or outdoor garden, controlling pests is a serious issue that every gardener deals with. Don’t be discouraged by pests: it doesn’t make you a bad gardener. Everyone is scared of them. That is why careful adherence to rules of cleanliness in your garden is a great practice to get into.
When you do find spider mites, quarantine the affected plants and get on that regimen of eradication. More than anything, you don’t want them spreading throughout your entire garden. If you keep on top of things, you should be able to contain and control the problem. If you are faced with an infestation that is simply out of hand, it may be best to simply wrap a bag around the plant, cut it down, and get it out of there. Knowing when to cut your losses is a big part of growing.
I hope that this blog has given you some good information to take to your garden practices. If you have any questions, our team is here to help. Diligence is your greatest ally, however. Keep to smart practices, keep a level head when problems arise, and you will survive this horror movie!