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How To Quickly Deal With Blackfly On Nasturtiums!

If you are growing nasturtiums in your garden, you are probably wondering what pests you are likely to deal with – or possibly already dealing with those pests. It is highly frustrating when you spend time, energy, and money on growing something and an insect in your garden decides to mob it and destroy it.

Most people don’t mind sharing the odd leaf with invading insects, but when you get masses of one insect all over one of your beloved plants, it can be very frustrating and even upsetting.

Blackfly on nasturtiums are a major nuisance, and most gardeners have come to hate them, because they will infest a plant and completely swamp it, and they can be tricky to get rid of once you have got a bad infestation going.

Nasturtiums are grown for both their beautiful flowers and their leaves, both of which are edible and can be used in salads – they have a slightly peppery flavor and a robust texture.

If you are growing your nasturtiums to eat, you are even less likely to want to share them with these pesky insects, which will cause major havoc.

It can be really hard to deal with a bad infestation of blackfly on your nasturtiums, but there are a few solutions you can try – which we will cover in this article.

Remember that if you leave a bad infestation of blackfly around, they may spread to your other plants and harm those too.

What Are These Black Flies On My Nasturtiums?

The black flies on your nasturtiums are usually a tiny black breed of aphids, and they are so small that they can look like soil or dirt has got spread over the plant, rather than it being covered in insects.

These flies prefer more temperate climates, so you won’t see them in very hot countries, but they can be a nuisance anywhere cool enough for them to survive, and they can gather on nasturtiums in such numbers that they almost completely conceal the leaves.

Some years seem to be worse than others for these insects, which may also be referred to as black bean aphids, and which can infest all kinds of plants, including your nasturtiums.

If your nasturtiums seem to be getting them badly, you should step in as early as possible, because the insects will quickly multiply and get harder to address.

The black flies on your nasturtiums will drink the plant’s sap and gradually wear the plant down, especially if they are numerous. Keeping them in check can be tricky, but it could save your plants.

Can Blackfly Kill Your Nasturtiums?

If they are present in large enough numbers, blackfly could kill your nasturtiums, yes. They pierce the leaves and stems with their mouths to drink the sap, which causes stress to the plant and robs it of the vital resources that it needs in order to keep growing.

A stressed nasturtium will struggle to grow well, even if it isn’t having its energy stolen by a host, so if this continues, the plant will often die, no matter how strong it was when the invasion started.

You need to make sure that you give the plants a chance by removing the blackfly from them. The longer you leave these insects to feast on your plants, the greater their numbers will become, the more they will stress your plants out, and the more likely it becomes that your plants will die.

You therefore need to make sure that your nasturtiums are free from blackfly as soon as you can, rather than leaving the problem to get progressively worse.

Keep checking your plants regularly throughout the season, and if you see these little insects appearing, take action as soon as you can.

Do You Have To Remove Blackfly From Your Nasturtiums?

You should remove blackfly from your nasturtiums, yes – because these insects will damage your plants.

If you just want to enjoy the flowers, they will prevent you from doing this because they are unsightly and will ruin the display of color, as well as causing blemishes on the leaves.

Your nasturtiums will probably fail to produce many flowers, because they will be too stressed by the insects.

If you want to eat the nasturtiums, it’s even more important that you remove the blackfly so that your plant can focus its energy on producing leaves, rather than dealing with pests.

This will give you a larger crop and ensure that you get to enjoy the results of your hard work in growing the plants. If you leave your nasturtiums infested, you will probably find that they only have enough energy to produce a few leaves.

You therefore do need to remove blackfly from your nasturtiums as soon as you realize that the plants have been infested.

Failing to do so will often kill the plants, meaning that all your efforts in growing them will be wasted. Even a serious infestation can be got rid of, but the sooner you take action, the more likely your plants are to thrive.

What Will Eat The Blackfly On My Nasturtiums?

The best thing for eating the blackfly on your nasturtiums is the humble ladybug: this is a surprisingly voracious predator that will attack any insects like aphids and blackfly.

Many people are surprised to learn that ladybugs can be ferocious, but they are one of your best friends when it comes to dealing with garden pests, and they will take care of many different kinds of insect infestations.

Ladybugs are an ideal option for a whole number of reasons, and you can either find them locally and put them on your plants, or purchase ladybugs online specifically for this purpose.

One of the best reasons for using ladybugs in your garden is that they are a completely natural form of pest control; they won’t harm your plants or other wildlife nearby, or upset the ecosystem, because they are already a part of it.

They can therefore be specifically targeted to deal with the insects you are having trouble with, and they are perfect for getting rid of things like blackfly.

Ladybugs are also a fascinating form of pest control, and much more beneficial for the planet – and you may enjoy the benefits in more than one place, if the ladybugs choose to relocate to another part of your garden and munch on other pests when they have finished on your nasturtiums.

Even if they don’t stay, increasing the number of insect predators may be beneficial overall.

How To Get Rid Of Blackfly On Nasturtiums

Ladybugs are one of the effective ways of getting rid of blackfly, but there are other options too – such as removing them by hand.

This works well if your nasturtiums are still delicate and you don’t want to spray any chemicals on them, because all you need to do is put on some gloves and work your way along the leaves, brushing the insects off and squashing them as you go.

Because blackfly are so dark, they are easy to see against the green leaves, and this can cut down on an infestation very quickly – although some are likely to remain.

If your nasturtiums are large and robust, you can also use a strong spray from a garden hose to remove them from the plant; this will knock the insects off and often drowns them, although it isn’t guaranteed to do so.

They may climb back onto the plants or fly to another part of your garden if you are unlucky.

Some people remove the most badly affected plants and compost them, and you may wish to do this if you have a lot of plants and only a few have been infested, as it’s a simple method for cutting down the numbers quickly.

However, it won’t work well if you only have a few plants, or if the blackfly are widely dispersed across them. In these cases, opt for the other removal methods if possible.

Is Soapy Water Good For Removing Blackfly From Nasturtiums?

Many people use soapy water to deal with garden pests, and this can be an effective option if you are struggling to get rid of the blackfly.

Insects breathe through their skins, and the soap clogs up their pores and suffocates them, so it can devastate the insect population in minutes (although you will almost always get a few survivors, no matter how much care you take).

Soapy water is therefore effective for removing blackfly from nasturtiums, yes, and if you put some dish soap and water in a spray bottle, it is very quick and easy to walk around a patch of nasturtiums, squirting every plant with a thorough dose to get rid of the invaders.

It will not harm the plants, although you should make an effort to thoroughly wash any leaves you later eat, so you aren’t ingesting any remaining soap.

It may take a few applications to get rid of the blackfly completely, as they tend to hide under leaves and in crevices, and some will survive the soap and start breeding again.

Overall, this is an effective method, but you should be aware that it will also kill beneficial insects, like ladybugs, reducing the number of predators that you have to naturally control the pests.

For this reason, soapy water isn’t the best option for getting rid of blackfly, although you can certainly use it if you are unable to get rid of them using other means.

How Do I Keep Blackfly Away From My Nasturtiums?

Keeping black flies away from your nasturtiums, or any other plants for that matter, is extremely difficult and isn’t really worth doing.

They are too small to net your plants against them, and they won’t be easily deterred, so it’s generally easier to remove them when they are there, rather than trying to prevent them from appearing in the first place.

However, some sources claim that spraying your plant with peppermint oil will put them off, as many insects dislike the strength of minty substances and will therefore avoid them.

Few people have any success when they try to keep blackfly off their nasturtiums, because the peppermint oil will not stay effective for long, if it works at all.

It will quickly be washed off by rain and blown away by wind, so unless you can constantly keep reapplying it, it isn’t likely to be very effective in protecting your plants.

Some people attempt to protect their plants by providing a sacrificial crop that will lure the insects to another part of the garden – but this has debatable success, because of how fast blackfly can breed. If you try this, be aware that the blackfly may decide they prefer your nasturtiums anyway.

Why Do Blackfly Like Nasturtiums So Much?

It isn’t clear why blackfly like nasturtiums so much. They will attack a whole range of plants, but they do seem to have a particular love for nasturtiums, which surprises some people, given the peppery flavor of these plants.

It is possible that nasturtiums are popular because their leaves are so wide and provide the blackfly with large areas that they can shelter and hide under.

The insects may be more exposed on other plants, and more vulnerable to predator attacks and inclement weather.

Overall, however, we can only speculate about why blackfly are so keen to eat nasturtiums. The popularity means that nasturtiums are often planted as a sacrificial crop themselves, which is unfortunate if you want to grow them for a salad or display!


Blackfly on nasturtiums are very frustrating, and they can be tricky to control once they have reached significant numbers, because they are fast breeders and pretty resilient. However, there are some effective pest control methods, and ladybugs are a particularly eco-friendly and low maintenance way of getting rid of the insects, so give this a try if your nasturtiums are suffering. You can also pick the blackfly off by hand, spray them with a hose, or try diluted dish soap on them.