How to Control Aphids Organically in Vancouver Gardens

Aphids are a common garden pest in Vancouver and across BC during the spring and summer growing season. These tiny insects can cause significant damage by sucking sap from plants, leading to weakened growth and distorted leaves. For gardeners in Vancouver, finding effective and organic methods to manage aphids is vital to maintaining a healthy garden. In this blog post, we share our go-to strategies for organic aphid control in Vancouver.

Identifying Aphids and Understanding Their Impact

Aphids are small, soft-bodied insects that feed on a wide variety of plants, including vegetables, fruits, and ornamental plants. They are particularly notorious for producing a sticky honeydew (a fanciful euphemism for their excrement), which causes its own set of problems.

Often, the first sign you have aphids isn’t the small insects themselves. Instead, you may notice a steady line of ants marching up the stems of the host plant. Ants “farm” aphids, protecting them from predators in exchange for their honeydew, which ants enjoy as a food source. Another sign that you might have an aphid problem is that a plant’s leaves are unusually shiny and sticky (there’s that aphid “honeydew” again). And yet another symptom of aphid infestation is the appearance of black patches on plant leaves: a fungus called sooty mold, which thrives while growing on the surface of honeydew-covered leaves.

Aphids do have favourite plants they seem to be continually drawn to (nasturtiums, dahlias, and Sambucus spp. come to mind), but they’re also attracted to the new growth on a variety of plants, as well as struggling and already-weakened plants.

Managing Aphids Naturally

Despite how annoying they can be, aphids are relatively easy to control and live with. At Figaro’s Garden, we recommend a multi-pronged approach:

1. Prevent aphid populations from getting out of hand

Preventing aphid infestations begins with maintaining a healthy garden:

• Build your soil: Healthy plants are less susceptible to aphid attacks, and more resilient when they are visited by the pests. Give your plants the best chance at success by growing them in soil that’s rich in both organic matter and nutrients. Depleted soil=depleted plants.
• Utilize companion planting: Certain plants, like garlic, chives, and marigolds can repel aphids. On the flip side, plants such as dill, fennel, cilantro, and sweet alyssum attract ladybugs: the aphid’s fiercest predator. Consider strategically incorporating these into your garden layout.
• Regular inspection: Check your plants, especially the undersides of leaves, for early signs of aphid infestation. They’re easier to control while populations are small.

2. Work with nature to control aphids

When prevention isn’t enough, these organic methods can help control aphid populations:

• Attract beneficial insects: Encourage natural predators like ladybugs, lacewings, and parasitic wasps by:
  • planting their favourite nectar sources
  • providing a water source
  • ensuring a succession of blooms from late winter through fall.

• • Wait and watch: Sometimes, the best attractant for predators are the aphids themselves. Familiarize yourself with what ladybug larvae and ladybug eggs look like; the latter can often be found on the undersides of leaves. Ladybug larvae are the most accomplished aphid eaters. If ladybugs are already present, don’t do anything except sit back and watch them take care of the problem for you.

• Treat the plant, not just the pests: Bolster your plant’s ability to defend itself by fertilizing lightly with a kelp-based liquid fertilizer. This tonic will improve overall health without encouraging abundant new leafy growth. Take care to avoid fertilizer with a high ratio of nitrogen: aphids love to attack the new growth caused by nitrogen

3. Use organic aphid control methods

Given Vancouver’s temperate climate, it’s important to tailor aphid control strategies to local conditions:

• Water spray: A strong jet of water can physically remove aphids from plants. This method is particularly effective during Vancouver’s wetter seasons, when insecticidal soaps are less impactful. Aphids knocked to the ground are unlikely to find their way back to the plant.
• Insecticidal soap: This is a low-toxicity option that works by disrupting the structure and permeability of the insects’ cell membranes, quickly killing them. To be effective, they must be sprayed directly on the aphids themselves; spraying the plant alone won’t work. While there are many recipes for homemade soap sprays available online, we have also seen accidental damage to plants from these home remedies. We recommend and sell Safer’s Insecticidal Soap for its specific formulation.

Why we don’t sell ladybugs at Figaro’s Garden

Gardeners are often told that purchasing ladybugs is a natural and effective way to reduce aphids in their yards, however, the practice is rife with problems:

• Ladybugs sold commercially are “wild harvested”: collected during hibernation from natural congregation points, typically in California. Some entomologists believe that “field-gathering the dormant insects by the millions shrinks the population available to farmers, prompting heavier pesticide use” (Boston Globe).
• It’s unclear whether commercially sold ladybugs are actually efficient for aphid control. A Cornell University report says, “Commercial insectaries distribute beetles that have been “harvested” from natural winter aggregation sites. If lady beetles are collected in this dormant state and transported for field release, even among aphid infestations, they usually migrate before feeding and laying eggs. This migratory behavior before feeding is obligatory. Releases of such ‘harvested’ convergent lady beetles could be a waste of time, money, and beetles.”
• They may “introduce disease-carrying pathogens to their wild [native] counterparts” (Boston Globe).

Instead of purchasing ladybugs as a method of organic aphid control, we encourage you to use some of the natural methods of attracting these beneficial predators while using some of the other aphid management practices listed above.

Visit us at Figaro’s Garden for more advice on organic aphid control in Vancouver!