Indoor plants do attract bugs, but those bugs are rarely harmful to humans, and relatively unintrusive to plants. Whether you’re growing seedlings indoors, on a windowsill, or under heat lamps, they will always be a space where bugs congregate.
Those bugs can be aphids, thrips, whitefly, spider mites, spiders, slugs, or anything else. If it can get in, it will find your plants. In this article, we’re going to share some tips for reducing bugs on indoor plants, and potentially stop them altogether.
Do indoor plants attract bugs?
Indoor plants attract bugs. There’s no gentle way to phrase it. Any insect, pest, bug, whatever you might call it, sitting in wait in your home is effectively starving, waiting for any food source it can find. So, as soon as you introduce plants to your home, it stops being an arid, lifeless space and makes it possible for insects to survive.
However, indoor plants in good condition are rarely overcome by pests, and will sometimes completely avoid them altogether, but this is usually down to luck rather than planning.
Can you prevent bugs on indoor plants?
Thankfully, you can actively discourage, and reduce bugs on your indoor plants, so you can breathe that sigh of relief now.
With organic sprays, clever companion planting, netting, and a few DIY hacks, those bugs will be a thing of the past.
The most common indoor plant pests
Indoor pests are much the same as outdoor pests, but the smaller ones are much easier to spot inside and up close. So those frustrating spider mites that often go unnoticed on mature garden plants can be a big problem, particularly for young tomato and pepper seedlings, which are tough enough to grow at the best of times.
Aphids
Aphids are small enough to get in anywhere. Adult females can fly in through a window, and larvae can live in your compost through winter, and hatch when the soil warms up. For seedlings in propagators, that’s often all it takes for a new infestation, so keep a constant eye out for young pupating insects crawling out of the soil onto tiny seedlings.
Whitefly
Whitefly are even smaller than aphids and are attracted to brassicas in particular. If you’ve grown young brassica seedlings indoors over winter, it’s a good idea to take them outside as early as possible in spring. Most brassicas are frost-hardy, so will prefer to be outdoors anyway.
Once whitefly are in the house, they can be very hard to get rid of without using insecticides.
Thrips
Thrips are more common on mature plants, so can be a problem for houseplants. I’ve heard stories of gardeners having thrip infestations on indoor seedlings, but have never found it to be a problem myself. If you do notice the small green insects, or the black adults on seedlings, try to rinse them off every few days to reduce the problem. Using insecticide or rubbing alcohol is too potent for vegetable seedlings, so should be avoided until your plants are at least 3-4” tall.
Mealybug & Scale
Mealybug and scale are a side effect of having houseplants. They won’t choose vegetable seedlings over other types of indoor plants, but can sometimes end up there by mistake. If you’ve got a strong stomach, the best way to get rid of mealybug and scale is to squish them, one by one.
Fungus Gnats
Fungus gnats are tiny black insects, less than 1/8”. They move quickly and cause the most damage while eating roots, particularly of young seedlings. Their eggs live in soil and compost through winter, so cleaning seed compost is essential, as well as disinfecting any pots or seed trays before planting.
Spider mites and Spiders
Spider mites are tiny arachnids, but have slightly different lifestyles and life cycles than their larger cousins. However, both will spin webs and make homes on humid trays filled with seedlings. Spider mites benefit from the young plants, packed with nutrition chlorophyll, while spiders thrive in this warm indoor corner, knowing that aphids, whitefly and gnats are about, proving all the food they need.
Their presence can increase humidity, and stunt plant growth, so remove them however you see fit.
Slugs
The idea of slugs in the house isn’t overly appealing, so it’s important to be careful when growing seedlings. Slugs can carry disease, bacteria, and even poison into your home depending on where they have been. Keep windows and doors shut and close off any gaps where they could get in.
If you notice slime trails check the base of pots, and under the rim, where slugs can hide during the day.
Organic pest prevention for indoor plants
Indoor plant pests are not part of a wider food chain. Once they enter the home and settle on your plants they have no natural predators, so the common advice of using prevention rather than cure is less appropriate. If you’re not squeamish about dead bugs, killing them is the only way to completely eradicate an indoor infestation.
However, if you prefer to use less hands-on methods, there are some effective deterrents. Sprays, insecticides, and chemical treatments should be used with extreme caution as seedlings are not yet strong enough to handle these methods.
Sprays
For more mature seedlings that are almost ready to be planted outside, there are some excellent organic pest control measures that work just as well for seedlings as they do for houseplants:
- Neem oil
- Horticultural soap
- Castile soap
- Lemon
- Eggshells
Neem Oil, Horticultural soap, and Castile soap all work in the same way. They suffocate and dehydrate insects using naturally occurring chemicals. Young seedlings won’t be able to cope with the mild toxicity, but older plants with reasonably well-developed roots can be treated regularly with these sprays.
Eggshells are a useful way to both prevent pests and help seedlings as they develop. Make sure you clean them thoroughly, as dirty egg shells will attract pests, not prevent them! Gently crush the eggshells, so they are in large pieces, and sprinkle the whole lot over the surface of your seed trays after germination. The calcium can help to support the development of tomato and pepper seedlings while keeping slugs at bay.
If you have any leftover lemons from cooking or cocktails, leave the empty hull near your plants. Citrus puts off most flies, and actively deters others. Fresh lemons work better than used ones, but if you’ve used the zest, or juiced it already, it will still work.
Pest repelling plants
The three best general pest repellents are mint, lavender, and chrysanthemum. Any member of the mint family will work, but lemon balm is the most effective as it also contains citronella.
Obviously, planting herbaceous perennials and woody shrubs in the house is more likely to promote bugs than prevent them, so using dried stalks is a sensible alternative.
At the end of summer, harvest a large bunch of mint, and any lavender cuttings you’ve pruned after your plants have finished flowering. Hang them up somewhere bright, dry, and ventilated, then seal the dried herbs in an air-tight bag. In spring, they’ll be ready to hang up around your seedlings, with the added bonus of their rich herbal perfume.
Chrysanthemums should be treated just like lavender, but are usually finished with flowering in early winter, so should be cut back after that. The leaves and flowers are equally useful when dried.
Releasing ladybugs
It might sound extreme, but releasing ladybugs into your home will quickly eradicate houseplant pests. You’ll have ladybugs around for a week, but they will quickly find the door when they’ve eaten what they can.
Are organic pest controls safe for pets?
Most organic sprays are safe for pets, and those that aren’t, usually smell so bad that pets won’t go near them until they dry anyway. We’ve got four cats and two rabbits, and they all reliably hate neem, Castile, and horticultural soap so much that they won’t even go in the room.
Some though, like citrus sprays, concentrated menthol essential oils, or chrysanthemums can be dangerous for pets. While most pets are predisposed to dislike citrus smells, some will take a liking to it (two of my cats hate citrus, but the others can’t get enough of it).
A word on yellow sticky traps
If you’re hoping yellow sticky traps will help solve your fungus gnats problem, you’re partially right. Fungus gnats are attracted to the yellow color and as they land on the sticky surface, they get stuck and eventually die.
Sticky traps attract all kinds of soft bodied insects, including aphids and whitefly. The problem is, your yellow sticky traps will only catch adult fungus gnats, which will still have time to reproduce and lay eggs. If you’re not addressing the problem in your soil, you won’t be able to get rid of them completely.
It’s best to use sticky traps in conjunction with applying fungicides/pesticides to your houseplants’ soil, bottom watering and making sure the growing medium is well draining.
Conclusion
There are many ways to get rid of pests on your indoor seedlings, and a few tried and tested methods of preventing them altogether. As with most gardening problems, indoor pests are part of the ride, so don’t beat yourself up if you find bugs on your houseplants or spring seedlings. Recoup, prepare, and do what you can to fix it.
Personally, I prefer dried herbs and eggshells. They don’t work against every possible pest, but they do the job of getting my indoor plants through spring, largely bug-free until they’re ready for the garden. Then it’s just a case of dealing with three more seasons of outdoor pests! Hurrah.
