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Do Your Plants Have Bugs?

A common question and concern from our customers! The answer is YES, absolutely, 100%! Not only do we have bugs, we actually spend thousands of dollars every year to buy them!


We all know that “nature happens” and insects are part of nature. All greenhouses and gardens will get insects every year, without question, because they mostly fly. That means when we are venting in greenhouses, or just have an open yard, insects have easy access and a super ability to find a food source.

Up until recent years the only control method for large greenhouses was chemicals. Today, we have a few companies specializing in biological control.

It has been well reported that pesticides containing Neonicotinoids are linked to collapsing bee colonies.  As a grower, I can say that the most effective chemicals contain  Neonicotinoids (of course they do, right?). So it makes sense that they are so commonly used.

At The Root Seller we try to avoid using chemical pesticides. As we proudly grow over 90% of our plants from seeds and cuttings, almost everything we sell are subject to our biological controls from the beginning.

What do you call a pest that isn’t a pest? A beneficial!

Every week, starting in February and ending in June, we buy insects and release them into the greenhouse. As crazy as this may sound, we specifically choose insects that either eat, or are a parasite to, common greenhouse bugs.

Aphids, whitefly, thrips and spider mites all eat or suck from plant leaves, causing damage, stunted growth, and ultimately a sub-par plant in looks and performance.

Shore flies and fungus gnats live in the soil surface and are often referred to as “fruit flies”. They all live off the algae on the surface of the soil, or any decaying matter (which is why they appear in offices if you leave food in your garbage). We also buy insects to keep these pests at bay!


Bug Juice

To control our aphids the first thing we need to do... is buy some aphids! Yes, that's right, we buy aphids.

As soon as the greenhouse opens up we buy some wheat grass covered in aphids. From this point, we seed more wheat grass and multiply the aphids. We want lots of aphids, but in a controlled way. So, we farm a type of aphid that very typically is only attracted to grasses. This narrows the scope for it spreading crop wide.

Once the aphid farm is big enough, we buy an insect called Aphidius colemani and release it into the farm. The aphidius is a flying parasite to aphids and has a very keen ability to find them! When it finds the aphid the Aphidius deploys an egg into the abdomen. From here the egg grows, killing the aphid, and then hatches a new Aphidius to find more aphids and start the process again.

Our aphid farm becomes an Aphidius farm within a couple of weeks. Now we have a greenhouse full of aphid predators. The whole cycle takes between 2 and 3 weeks, which means if you see an aphid on a plant, it is probably already parasitized, which makes it a “beneficial”, not a pest!


If you own a Virginia Creeper or Hop Vine then you know exactly what whitefly infestations are! We buy an insect called Encarsia formosa which is a parasitic wasp to the whitefly. These come on cards, which we hang on the side of pots, and are released slowly as they hatch over a couple of weeks. We release these before we see whitefly just to stay on top of things. You may buy one of our plants with a card hanging off the side, and this is likely (or was) Encarsia formosa.


Spider Mites

To control our spider mites we buy an insect called Phytoseiulus persimilis. These are predatory mites that specifically target the two spotted spider mite, which is the most common in greenhouses. Typically spider mites are not too much of a problem in the yard as they hate wind, which there is not much of in a greenhouse. They love hot and dry.

Thrips and Shore Flies

p4 bugs

In my opinion this is one of the worst pests to have and control. They are everywhere, and my college entomologist told me the reason they are called “Thrips” and not “Thrip”, is because there is never only one of them. They are very small and love flowers but are very happy to suck leaves too. If you have grown cucumbers and they turn out curled, it is because of thrips. Its baby stage is spent in the soil then it moves to the plant for its adult life. For this we buy in a nematode called Steinernema feltiae. This gets mixed with water, then we barrel pump it into the growing medium of the plants. The Nematode moves through water so keeping the soil damp for a week is important.  Steinernema feltiae is a parasite to the baby stages, which is larvae and pupae stages of insects that live in the soil or growing medium. This means we are killing them before they become the leaf- and flower-destroying insect known as thrips.

Fungus Gnats

To control these we use a mite called Hypoaspis. They live in the top 1/2” layer of the soil and are a predator to fungus gnats primarily. These beneficials arrive living in a bucket filled with bran to give them a food source on their travels, and also as they are spread across the crop! Fungus gnats are a pest because they feed off decay and soil algae. This makes them an efficient transporter of root rot diseases and mold in general.

Biological control is a fantastic way of keeping pests at bay. Everyone wants plants with no bugs or pests on them. The ironic thing is, without those bugs or pests, our entire control method would be a waste of money! The predators we purchase need to have a food source or rebirth method around them otherwise they go somewhere else to find it. We basically add these predators on a weekly basis to keep their numbers up during “drought” times.

Fungus Gnats

The absolute honest truth is that it's easier and substantially cheaper to spray chemicals.

Biological control requires a lot of work and upkeep, monitoring and deployment. Plus the time it takes to order on a weekly basis.

You can apply chemicals once and have results for upto 4 weeks. I understand the use of chemicals but we as a family and as a business do not believe it should be our first option in pest control.

Great time and money is spent on using the biological control method. This does mean that plants may have the occasional bug on them as a result. That bug may already be parasitized and ready to be a beneficial in your very own yard! Sometimes it may just be a bug alive on a plant. This is nature and we are trying to control it with nature! So I suppose the best question is.... Do you want bugs on your plants? The other alternative is chemicals!


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The Root Seller
16735 Zaychuk Rd.
Edmonton, AB

Mon - Fri: 9am - 5pm
Holidays: 9am - 5pm