What to do about aphids?

21:49, Nov 18 2012

Aphids literally suck the life out of your plants. They're sneaky, sometimes tiny, and though a small infestation doesn't do too much damage at first, they breed like crazy and can quickly wreak havoc. They can also spread disease. I get them on my herbs in particular - especially those I grow on my windowsill. My indoor chilli plant also gets knocked about by them, and last summer I tried many techniques that temporarily got rid of them, but not permanently. 

How do you know you have aphids? Aphids look a little bit like green, yellow, red or black dirt on a plant's stem or leaves. They tend to hang out in clusters, and don't move much. Groups can be made up of winged aphids, which are much larger, and little green ones which look almost like specks of dust. There are several different varieties, imaginatively named things like "carrot aphid" and "strawberry aphid". 

So now you know what to look for, what do you do about them? There are several approaches you can take. But beware - you need to be vigilant and keep on top aphids once you've spotted them. They will return. 

1. If the infestation is small, you can pinch them off. I do this often with the aphids on my windowsill herbs before they can get a foothold.

2. If you plant is fairly sturdy, a strong jet of water from the hose can effectively drown aphids and wash them off plants.

3. My friend* Hugh Fearnley-Whittingstall recommends growing nasturtiums as a companion plant - aphids don't like them and will stay away from anything planted nearby. 


4. There are sprays you can try. Pyrethrum works - I used to make my own but it's far less time consuming to use a ready made one these days. Just make sure you spray after dusk so you don't kill any bees that may come along to visit.

5. Another spray is made from a teaspoon of dishwashing liquid in an litre of water. You can then wash the spray off with water.

6. Ladybirds are not only pretty, they love to chow down on aphids. I've read they like coriander, dill, fennel, cosmos and geraniums. 

7. Another commercial spray is neem oil, which is suitable for organic gardeners, made from the neem tree. It has a compound that stops the aphid mating and eating, and thus it dies. 

8. Be vigilant and determined. Aphids can be hard to spot in crowded gardens, regular inspections of plants mean infestations don't get too out of hand and are less hassle to control.

* Not actually my friend

Have you had issues with aphids? What do you use? 

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