Pests and plant disease are always the bane of any gardener’s existence. Trying to control pests and disease in an indoor garden can be particularly challenging, given that it is also your home and the environment you and your family directly live in. Normal chemicals and sprays won’t work for fear of poisoning the air your breath and the usual beneficial bugs that are recommended (bees, ladybugs, spiders, etc.) would not be practical in a home environment. (at least not yet…) Companion planting and some homeopathic remedies can also be ineffective in an indoor or potted environment. So what’s an indoor gardener to do?
After years of managing a large indoor garden I’ve found a combination of solutions that are effective and safe. First off, think small! While we can’t invite bees or ladybugs into our home, we can easily employ some microscopic beneficial bugs to keep most pests at bay. A lot of these appear naturally in the great outdoors, but inside we’ve created a more sterile environment so it can be useful to re-introduce some of the smaller beneficials back into our soil. Second, the use of certain types of carnivorous plants can be an easy and fun solution to fruit flies and fungus gnats. (A lot more fun than hanging those sticky traps) Finally, a judicious application of neem oil or a vinegar/water mixture can help take care of the majority of other problems that are left.
Neem Oil and Vinegar/Water Mixtures
Lets start with the sprays first! Neem oil is a vegetable oil pressed from the fruits and seeds of the neem (Azadirachta indica), an evergreen tree found in the tropics. It has been used in farming and agriculture for hundreds of years to help control things like mealy bug, aphids, cabbage worm, thrips, whiteflies, mites, fungus gnats, beetles, moth larvae, leafminers, caterpillars, locust, nematodes, and Japanese beetles. It can also help control black spot, powdery mildew, anthracnose, and rust fungi. In the U.S. I’ve found Neem oil commonly sold in either a spray form or a concentrate form. The concentrate can be diluted with water and turned into a spray or a liquid that can be poured directly on the soil to kill anything within the top 1-2″. The spray form is good for spraying on leaves, flowers, fruits, etc. Neem oil is a safe and natural multi-purpose fungicide, miticide, and insecticide. Several applications a week apart is usually recommended, especially for heavier infestations. But, you might be thinking, what about XYZ pesticide?! It kills everything! Yes, I’ve gotten and used a few of those… they have resulted in fruit drop on my citrus trees, killed my blooms, and stained my wall! Stick to multiple applications of something less deadly… it’ll pay off in the long run.
For mold (usually from too much watering) on the soil or the side of a Terracotta pot or calcium deposits I like to spray on a mixture of 1 part water to 1 part regular white vinegar. I find this an easy and quick solution to mold problems. Avoid spraying on leaves, flowers or fruits because it can burn the foliage. A lot of people recommend this to “kill” weeds in the yard. It doesn’t actually kill the root structure of the weed, it just burns the top of the weed that is above ground.
Erase from your mind images of Venus Fly Traps or Pitcher Plants! While those are lovely plants, and what most people think of when they think carnivorous, they are not what I have in mind here. I have tried and failed a variety of times to keep both of these types alive. I’m not sure if it’s bad stock or if it’s my care. (probably my care) Either way, the point is both of these require a certain type of care and they generally require larger food sources than your average infestation of gnats or fruit flies. I’m speaking generally here, I do have a baby flytrap that I’ve managed to keep alive on a diet of gnats but that’s about it.
Did you know that there are over several hundred known species of carnivorous plants on our planet? The two that I would like to bring to your attention today are the Sundew (Drosera) and the Butterworts (Pinguicula). My absolute favorite is the Butterwort, but both of these work similarly. Tiny insects, in our case gnats, fruit flies and white flies, are attracted to their leaves and land on them. They are then immediately stuck like they would be on a sticky paper trap. The insect is then slowly dissolved and absorbed into the leaves of the plants. Both of these are found through out the world so their climate and care can have some variance. I’ve been lucky to live in a town that has a great carnivorous plant club, which is how I stumbled upon this alternative to fly paper and acquired my collection of small plants. Seriously, I have one intermixed in every group of plants I have, including by my hydroponic systems. I keep them in a little water tray and whenever they start getting dry I fill the tray with distilled water. (It MUST be distilled, tap/well water has too many minerals) I have them in a variety of lighting conditions and rotate them around depending on how many bugs they’re catching. This has done absolute wonders for our fly problems and is a lot cooler and definitely more effective than hanging up traps. Search around for a local source near you or check out some of these online retailers here, here, or here.
Want to learn more? Check out The Savage Garden by Peter D’Amato.
You can also check out the International Carnivorous Plant Society.
First, shout out to Ray over at the VoodooGarden for turning me on to Stratiolaelaps scimitus Womersley or Hypoaspis! During a horrible spider mite infestation, I took a chance and ordered some. I haven’t looked back since! Hypoaspis is a wonderful predatory mite that goes after the eggs and larvae of fungus gnats, fruit flies, and any other bad thing crawling around in your soil. I order mine from Evergreen Growers, which ships anywhere to in the U.S., if you are outside the U.S. search around for a local supplier. Predatory mites and other microscopic beneficials are widely used in greenhouses the world over to control for all sorts of damaging insects that feed off your plants and can transmit disease. Why not fight fire with fire? These are NOT creepy crawly, you can’t even see them, and they remain in your soil or directly on your plant; so no traveling around your house. They arrive in a little tube or shaker jar and I just go around and give anywhere from 1-8 tsp. (depending on pot size) of growing medium (in which the microscopic bugs are residing) to my plants. It’s super easy and incredibly effective. I have recently discovered it even works on my hydroponic system. I got a horrible infestation of red mites and ordered some Galendromus occidentalis. I sprinkled it on and around my hydro system and within a week all red mites were gone. My S.O. refers to it as me sprinkling my “fairy dust” around the house. This is a fantastic way to control for common pests in an indoor setting without having to use chemicals and as you’ll notice below, one type of bug can get rid of multiple problems. It’s simple, safe, and relatively cheap compared to losing your hard earned garden!
Listed below are some commons pets and some recommended beneficials to combat them:
- Nematodes: Beneficial Nematodes like Steinernema feltiae, Steinernema carpocapsae, Heterorhabiditis bacteriophora, Steinernema kraussei, Steinernema carpocapsae
- Mealybugs: Cryptolaemus montrouzieri
- Fungus gnats/fruit flies: Carnivorous plants and Hypoaspis, both referred to above.
- Aphids: Aphidoletes aphidimyza, A. matricariae, A. colemani, A. ervi
- Spider Mites: Amblyseius fallacis, Phytoseiulus persimilis, Stethorus punctillum
- Thrips: Hypoaspis miles, Amblyseius cucumeris, Steinernema feltiae, Atheta coriaria, Orius insidiosus
- Whitefly: Encarsia Formosa, Delphastus catalinae, Eretmocerus eremicus
A simple Google search will always turn up hundreds, if not thousands of articles and recommendations on how to combat pests and disease in a garden. Like I said, a lot of these are not practical for an indoor setting. By no means are the solutions listed above an exhaustive list of what will work, if you have found something that works, please use it! (And leave a comment below) Combinations of these three things have worked well for me and I am happy to share them, but I know that there are a lot of other things that work well to. Find what works for you and good luck!