The Clever Way Smart Gardeners Eliminate Aphids

Have you ever had fresh plantings smothered in those sticky, crawling aphids? It’s not nice is it! But spraying chemicals on the plants you’re going to eat is rarely a smart move – so what should you do about it?

There are seven clever techniques smart gardeners use to tackle aphids naturally. Follow these and you’ll avoid the despair of failure!

Know Your Enemy

There are literally hundreds of different species of aphids: black bean aphids (also known as blackfly), greenfly, woolly aphids, cabbage aphids, peach aphids… the list goes on. They come in black, green, white, grey – even pink – and while most species are generalists, there are plenty that target specific plants as well. The good news is that no matter how many species there are, the way to deal with them is essentially the same across the board. So once you’ve cracked it with one, you’ve cracked it with most of them.

Aphids are soft-bodied and tiny, at around a tenth of an inch (less than 3mm) long. They cluster on new growth, in leaf crevices, along stems and on the undersides of leaves, where they pierce plant tissue and suck out the sap. This is what causes leaves to curl, pucker and distort. Left unchecked, aphids weaken plants, stunt growth and – perhaps most worryingly - spread disease from plant to plant as they move around the garden.

They also produce a sticky, sugary waste called ‘honeydew’, which coats leaves and encourages sooty moulds to take hold. And if you ever notice ants streaming purposefully up and down your plants, take it as a clear warning sign because ants actually farm aphids for their honeydew, protecting them from predators in the process. Think about that for a moment: aphids are basically livestock for ants. That’s quite incredible really, if also a bit annoying of course!

1. Spot Aphids Early

So what’s to do about it? Well, the single most effective thing you can do is to get into the habit of checking plants regularly. Make it part of your watering routine, taking a quick look under leaves, around shoot tips and along stems as you pass through with the hose or watering can - aphids love to hide! Catching a small colony before it explodes into a full-on infestation is so much easier than trying to deal with the aftermath.

Look for curling or puckering leaves, a sure sign that aphids are about and feeding. Search for clusters of tiny insects on new growth and buds. Inspect foliage lower down and on the soil beneath your plants, because aphids moult, shedding their old, papery exoskeletons which can accumulate there as colonies grow – they can look a bit like whitefly to the untrained eye. And after watering, watch for a milky, slightly cloudy runoff, which can indicate honeydew washing off an infested plant above. And, of course, follow the ants!

2. Act Fast

The moment you spot aphids it’s time to act, because aphids can reproduce at extraordinary speed. A single aphid can produce up to 80 offspring a week and – get this – in warm weather they don’t even need to mate to do so. That’s right, aphids can give birth without any hanky-panky involved, giving rise to all-female generations that are basically clones. Clearly, spotting them early and acting fast really matters! But thankfully, at this early stage, you’ve got some brilliantly simple options.

If it’s just a small cluster of aphids on a shoot tip, simply pinch it off between your finger and thumb and squash it. It may seem brutal but you’re nipping the problem in the bud, quite literally. For broader infestations on individual leaves or stems, cut those off entirely. All the growth can be safely composted, but just bury it down into the compost heap a bit so those pesky pests are safely tucked away.

One especially useful trick for broad beans is to pinch out the soft growing tips at the top of each plant once the first pods have started to set. This is exactly where black bean aphids love to congregate, so removing those tips does away with their favourite hangouts. Don’t throw away those pinched-out tips because they make surprisingly good eating, lightly steamed or stir-fried. Delicious and doubly satisfying!

3. Blast Off!

For larger infestations, one of the most effective and most underused tools in the gardener’s arsenal is the humble garden hose. Set it to a strong jet – that flat or cone setting you’ve probably never used before – and just blast the aphids off.

Aphids are soft-bodied and pretty feeble so, once they are knocked to the ground, most of them won’t make it back up into the plant. Do this every few days during a bad spell and you can keep populations low enough to save the plant without involving any nasty chemicals.

4. Call in the Cavalry

Now we’re getting into the really clever stuff, because the most powerful aphid control doesn’t come in a bottle or even a hose – it’s already out there in your garden, if you give it a reason to show up.

Ladybirds, lacewings, hoverflies, parasitic wasps, ground beetles… these are all your allies, and they are extraordinary aphid predators. Did you know, for example, that a single ladybird can devour up to 50 aphids a day, while their larvae are even more voracious. Over a lifetime they can eat over 5,000 aphids – not so much the feeding of the 5,000 as the 5,000 being fed on!

Parasitic wasps lay their eggs inside aphids, which are then consumed from the inside out. Nature is deliciously grim like that sometimes! And hoverfly larvae are essentially tiny aphid-eating machines. The key is to attract these beneficial bugs to your garden and keep them there, and that means flowers.

Simple, single-flowered plants are best because their nectar and pollen are easily accessible. My absolute go-to companions for the vegetable garden are poached egg plant, calendula, sweet alyssum and marigolds. Dot these flowers in and around your beds and they will draw in these aphid antagonists like a big, flowery magnet.

These are just a few of the fantastic companion flowers recommended in our Garden Planner, by the way. Once you’ve decided which you’d like to grow it’s easy to just select them and drop them into your plan. You can try out the Garden Planner with our 7 day free trial – you won’t have to share any payment details, and it’s a great way to check out all its features such as companion planting suggestions and its in-built growing calendar, which is based on data from your nearest weather station.

Blooming herbs are also extremely powerful insect attractants, so let your dill, fennel, parsley, thyme and mint go to flower to ensure a constant stream of visitors like hoverflies and parasitic wasps. The bonus, of course, is that you can still harvest the herbs themselves, and they look beautiful too.

Just a word of caution though: resist the temptation to buy in beneficial bugs and then release them, because without an established habitat, they’ll simply fly away. Build the habitat first and these predators will naturally find you – and stay.

And if you do see natural aphid predators about, you can usually trust them to do their thing. I once was just about to squish a fairly sizeable infestation of aphids on my pepper plants in my greenhouse, but spotted a ladybird hanging around so decided to leave them well alone to give the ladybird a chance to feed. Well, would you believe it – within days I had no aphids whatsoever! So if you do see a pest predator nearby, just let them get on with things - it might just save you from some grisly work!

5. Protect Vulnerable Plants

Sometimes the smartest move is to stop aphids reaching your plants in the first place. Fine insect mesh or fleece laid over susceptible crops like brassicas will create a physical barrier that aphids, including the winged forms that spread plant diseases, simply can’t get through.

This is especially worth doing from early to midsummer when winged aphids are on the move and the risk of diseases like Cucumber Mosaic Virus is at its highest. Cucumbers, spinach and celery are especially vulnerable, so prioritise these if you’re choosing where to lay covers. Just remember to remove the covers when plants are flowering if they need pollinating, and regularly check underneath just to make sure aphids haven’t somehow become trapped in there!

6. Grow Healthy Plants

A healthy, well-nourished plant in good soil, watered consistently and growing in the right conditions, is far less susceptible to falling victim to an aphid attack. Think of it like our own immune systems – if we look after the fundamentals, we are much better placed to fight off infection.

Build good soil using plenty of garden-made compost, don’t over-apply nitrogen-rich fertilisers, which produces the lush, soft growth that aphids love, water consistently, and choose your planting spots carefully, matching crops to the conditions they love. Get the growing conditions right, and aphid pressures noticeably drop.

7. Last Resort: Organic Sprays

For a powerful punch against aphids, dissolve a teaspoon of pure castile soap into about a pint (0.5 litre) of water in a spray bottle. Give it a good shake to mix. This soapy spray coats aphids and literally suffocates them on contact. It’s a cheap, effective solution, and it shouldn’t harm your plants.

An even stronger solution for genuinely severe infestations when literally nothing else is doing the trick is neem oil. It’s probably the most lethal option of all. It works by disrupting the aphid’s lifecycle by stopping them from maturing and laying eggs, while the oil itself smothers them. And if that wasn’t enough, it also stops aphids from feeding, causing them to starve. Mix it according to the packet instructions, then apply as a targeted spray.

But please, both of these sprays should only be considered as a last resort, because even ‘natural’ and supposedly ecologically friendly sprays can sometimes harm the beneficial insects that we need to help prevent bad infestations in the first place!

If you choose to use castile soap or neem oil, always try to spray in the evening, when bees and other beneficial insects have settled down for the night, and avoid spraying near flowers. Pick a still night so the spray doesn’t drift about. Be as targeted as you possibly can, focussing only on the infested areas rather than dousing entire plants.

I rarely reach for sprays myself. The combination of sharp eyes, fast action, and a garden full of beneficial bugs sees me through the season most years. And I reckon it’s worth tolerating small amounts of damage if it’s not immediately life-threatening to the plant – the presence of this natural prey will help to draw in those all-important aphid predators, after all.

If you’ve got a tried-and-tested method to beat aphids, I’d love to hear it, so do drop us a comment below.