Do Foliar Sprays Work on House Plants?

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I have to admit, I’ve ignored foliar sprays for the, uh, two years I’ve been into plants.

I assumed they were a bit of a gimmick, like misting, or Pink Congos.

My bad.

It turns out that they can be a pretty easy way to get some extra nutrients into your plants, and let’s face it, spraying stuff is kinda fun.

I’m not going to recommend any DIY foliar spray recipes, simply because I don’t know any (I have a shop-bought one) and the recipes I’ve seen contain products like coconut oil that seems a bit…stomata clogging.

Also there’s a very popular one that involves spraying your plants with milk, but I’m just not sure old milk smell is the ambience I’m after in my home.

That being said, if anyone has a recipe that they swear by, feel free to link it in the comments.

What is a foliar spray?

Foliar spray is simply a spray that goes on foliage.

Technically, bug spray is a foliar spray, but usually, products marked as foliar sprays contain fertiliser or other plant boosting ingredients.

Just stay away from any foliar spray that just boast ‘leaf shine’ properties. Shiny leaves aren’t something that’s going to help your plants, and sometimes leaf shine products can do more harm than good as they can block the leave’s stomata and inhibit respiratory function.

You can buy premade foliar sprays, or make your own. I have a store-bought one, just because it’s convenient.

The homemade route is absolutely fine, but be aware that if you’re using food items you may be setting yourself up for a gnat invasion.

The orchid spray that I got from my local garden centre was only £4.99, so it’s worth trying out.

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Is foliar spray effective?

Yes – if you get a good one.

I mean, we’ve all seen big industrial sprayers out in the fields spraying crops with fertilisers and pesticides. Foliar sprays are the same thing, albeit on a grander scale.

Granted, a lot of the spray will fall on the ground and be absorbed by the roots, but the same thing can happen with foliar sprays on plants in our homes.

Like with the human body, some vitamins are best absorbed through the skin than by the stomach. Vitamin B12 tablets, for example, are much more effective if you buy chewable ones and hold them under your tongue.

It’s kind of the same with plants if we think of the roots as being the stomach and the leaves as being the skin.

(That’s on the shortlist for the ‘Weirdest Sentence I’ve Ever Written’ award)

But also like medications, some plant nutrients can cause damage to the skin, so don’t wantonly spray your plants with whatever fertiliser you have lying around, or it will die.

With regards to vegetable/fruit plants, it’s considered good practice to use a foliar spray as well as regular soil fertilising. Seaweed fertiliser is a great candidate for a foliar spray because it’s pretty gentle.

That being said, I didn’t spray my tomato plants with a foliar spray, and I’m currently inundated with tomatoes.

But then I didn’t prune them properly (the guy that came to service my boiler was HORRIFIED) and I only fertilised them twice. I’m assuming beginner’s luck!

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How long does foliar feeding take to work?

If you fertilise your plants with a foliar spray, the nutrients will get into your plant faster than if they’re put in the soil, simply because they’re being directly applied to the plant.

How long it will take for you to notice a difference will depend on a few factors, such as how nutritionally deficient your plant was in the first place, how fast your plant is growing, how good other aspects of your plant care are etc.

BUT

Foliar sprays aren’t intended to be a replacement for fertilising the soil.

For one thing, consider the amount of fertiliser going into the soil when you water it in – even if it’s very diluted, it’ll be a damn sight more than if you’re just spraying a few drops on the leaves.

Also, depending on your soil, fertiliser will be held in the soil, so it has more longevity than foliar sprays, which will just run off or evaporate in a couple of minutes/hours.

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What’s the best foliar fertiliser?

The one I’m using is similar to this one, and…it’s fine. I’ve not noticed any dramatic differences, but it’s cheap, smells ok and it’s fun to do.

If you have a seaweed fertiliser, put a drop in a spray bottle and top up with water and use that. Just be aware that it will probably smell quite grim. If you prefer to use fish emulsion, it will probs smell awful, so maybe…don’t do that.

Or take all your plants outside and spray them there, leave for an hour or so for it to absorb and then hose them off.

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What’s the best time to use foliar spray?

Plant stomata tend to be closed 9-5.

This is intriguing to me. It suggests they’re at work, no?

I spray mine around 8am, just because, er, that’s when I remember to do it.

I wouldn’t worry too much about the timing of your spraying – just remembering to do it at all is enough for most people BUT I would advise not spraying your leaves when the sun is at its highest, just because chemicals + sun usually = burnt leaves, and we don’t want that.

With regards to how much to spray, I just…spray them. Fairly liberally, but you just want to make sure you’ve covered most of your plant.

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How often should I use foliar spray on house plants?

I would follow the same rule of thumb as I do with diluting fertiliser – half of whatever the manufacturer suggests.

There will probably be instructions on the back of the bottle. Mine says to spray 2-3 times a week, so I just spray once a week.

Controversially, I’m going to continue to spray mine all throughout winter, even my plants that aren’t growing for two reasons:

  1. What if it’s life-changing for my plants and I unlock the secret of unlimited, super fast plant growth??? That would be useful information for you!
  2. It’ll knock some of the dust off and hopefully make cleaning the plant leaves easier.
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Can I use orchid foliar spray on other house plants?

Eeeeeeerm, I do.

I’m hardly going to buy a separate foliar spray for each of my plant species (though by all means, you go ahead).

Unfortunately, the spray I have is very mysterious and secretive about it’s ingredients. The only clue it gives is that it doesn’t contain urea, and it does contain humic acid and fulvic acid. It could contain literally anything else.

But orchids aren’t particularly special when it comes to nutrient needs (are they???), and they’re, you know, plants. How niche could this spray be (worried face emoji).

I’ve been using an orchid foliar spray on most of my plants, and none of them have died a death. IT’S FINE.

(Obv’s I’ll update if something awful happens, or if all my plants start magically turning into orchids.

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