Making Nettle Feed: A Free Homemade Liquid Fertiliser

What is nettle feed and why does it work?

Nettle feed is a liquid fertiliser you make by soaking chopped nettles in water and letting the mixture ferment for a couple of weeks. As the plant material breaks down, it releases nitrogen, potassium and a range of minerals that were otherwise locked inside the leaves. What you end up with is a dark, strong-smelling liquid that acts as a mild, nitrogen-heavy all-purpose feed.

Gardeners often call nettles a dynamic accumulator, meaning their deep root system pulls unusually large amounts of nutrients up from the soil and stores them in the leaves. Alongside nitrogen, nettles carry useful amounts of calcium, magnesium and iron, which is also why nettle has a long history as livestock fodder and even soup greens before the leaves toughen up later in the season.

The nitrogen is exactly why nettle feed shines on leafy crops. Nitrogen drives leaf and stem growth, which makes it a good match early in the season while plants are still building themselves up. It's also why you should ease off once a plant starts flowering or setting fruit — too much nitrogen at that stage pushes lush foliage at the expense of the harvest.

Compared with a bottled liquid feed, nettle feed is weaker and far less precisely dosed. You never know exactly how much nitrogen a given batch contains, since that depends on how many nettles went in, how young they were, and how long the mixture fermented. It's a blunter, entirely free and low-impact tool rather than a substitute for a fertiliser with a declared nutrient analysis on the label.

When and how should you harvest nettles?

Pick nettles before they flower, generally sometime between April and June depending on your climate and how far north you garden. Young growth before flowering carries the most nutrients and, just as importantly, hasn't set seed yet, so nothing sprouts unexpectedly wherever you later water. If your patch has already started flowering, you can still use it — just snip off the flower heads before they go in the bucket.

No nettles of your own?

Most gardeners don't need to grow nettles on purpose. They turn up wherever soil is rich and a little neglected: behind a compost heap, along a fence line, in a ditch, or on waste ground. Ask around an allotment site if you don't have a patch — most nettle-owners are happy to see someone haul a bucketful away. Avoid harvesting next to busy roads or anywhere that may have been sprayed, since nettles take up whatever is in the soil around them, including things you don't want in your feed.

Stinging nettle (Urtica dioica) has opposite, heart-shaped, deeply toothed leaves covered in fine stinging hairs on both the stem and leaf surface. Don't confuse it with dead-nettle (Lamium), a look-alike with similar leaf shape but no sting at all — it also contains noticeably less nitrogen and doesn't ferment into nearly as strong a feed.

Wear gloves with real substance to them — thin disposable nitrile or latex gloves won't stop the formic acid in the stinging hairs. Ordinary heavy-duty gardening gloves or rubber dish gloves are enough. Cut plants back to about 10–15 cm (4–6 in) above the ground with secateurs or shears so the roots stay intact and push up fresh growth, which often gives you a second harvest in July.

Good to know. Never strip every nettle from one patch. Nettles are a host plant for several butterfly caterpillars, including red admirals and peacocks, so leave some standing if you want butterflies in the garden.

If you get stung

The stinging hairs contain formic acid and histamine, which is what causes the sting and the small raised welts that can last an hour or two. Rinse with cold water and try not to scratch, which only spreads the irritation. Crushed dock leaves, which often grow in the same patches as nettles, are a folk remedy plenty of gardeners swear by, but sturdy gloves and long sleeves from the start are the real fix.

How to make nettle feed step by step

1. Roughly chop the nettles. Smaller pieces ferment faster. Secateurs or a spade against the side of a bin both work fine.
2. Fill a bucket or barrel about halfway with chopped nettles. A 10-litre (2.5-gallon) bucket takes roughly one large bagful of nettles before they compress down.
3. Cover completely with water. Rainwater is ideal. Leave 5–10 cm (2–4 in) of headspace, since the mixture bubbles and rises as it ferments.
4. Stir, then weigh the nettles down with a stone or brick so they stay submerged. Don't seal the container airtight — the gas produced needs somewhere to escape.
5. Set the container outside, ideally somewhere shaded. Direct sun doesn't speed things up much, but it does help the smell carry further if the bucket sits near a patio or door.
6. Stir every two to three days during the first week. This adds oxygen and keeps the fermentation even.
7. Wait 10–14 days. Expect heavy bubbling for the first several days, tapering off after that. Once bubbling stops completely, the feed is ready.
8. Strain out the plant material through a fine net, an old pair of tights, or a thin fabric bag. Transfer the liquid to a covered container and store it somewhere cool and dark.

Common mistake. Heavily chlorinated tap water can slow fermentation, since chlorine kills off some of the microorganisms that need to break the nettles down. Let tap water sit out for a day before adding it to the bucket so most of the chlorine has a chance to dissipate.

White foam or mould on the surface — is that a problem?

A thin layer of pale foam on top is a normal part of fermentation. Stir it back in. A thick, fuzzy, blue-green or black mould, on the other hand, means something's gone wrong, usually because the nettles weren't fully submerged. If that happens, tip the batch onto the compost heap and start again with more water covering the plant material.

A faster, less smelly method using microorganisms

If the smell is a dealbreaker, add a splash of EM (effective microorganisms) along with a little molasses or sugar to the nettles before covering with water. The added microbes steer the fermentation in a more controlled direction, giving a sourer, less ammonia-heavy result than an uncontrolled brew. It takes a bit more planning but is worth it if the bucket has to sit close to the house.

How much should you dilute nettle feed?

Finished nettle feed is too strong to use undiluted — applied neat, it can scorch roots much the way over-strength synthetic fertiliser does. Always dilute before watering, and vary the ratio depending on how you're using it.

If you'd rather eyeball it than measure, dilute until the colour resembles weak tea. Darker than that, add more water. When in doubt, dilute more rather than less — an extra weak feeding never causes harm, while an overly strong batch can damage the root system of a sensitive plant.

A regular watering can is the simplest way to apply it. Dilute straight in the can, or mix a stronger stock solution in a smaller bucket and cut it with water by hand. If you're feeding a lot of ground and use a hose-end feeder, flush it thoroughly afterward — the fine sediment in nettle feed clogs the nozzle more than a typical bottled fertiliser would.

How and when should you apply it?

Water it in at the base of the plant, never over the foliage in bright sun — wet, feed-coated leaves in direct light can scorch and also raise the risk of fungal disease. Morning or evening works best, the same rule that applies to ordinary watering.

Start feeding once plants are properly established, roughly two to three weeks after transplanting, and continue weekly through the leafy growth phase. Taper off or stop entirely once a plant starts flowering heavily or setting fruit if you're growing tomatoes, cucumbers, squash or similar crops — excess nitrogen at that stage costs you harvest, not growth.

For a steady supply all season, start a new batch every couple of weeks from April to July. That way you're never left without feed when one batch runs out, and there's always a fresh one ready whenever the nettles need cutting back anyway. Marking the start date directly on the bucket with a marker or a piece of tape is a small habit that saves confusion — it's surprisingly easy to lose track once you have more than one batch going at different stages, and a forgotten bucket loses potency without any obvious sign until it simply stops working as well.

Which plants benefit from nettle feed?

Nettle feed's nitrogen-heavy profile suits plants that are currently building leaves and stems, and suits far less anything already deep into flowering or fruiting.

Once a plant is flowering and fruiting, a composted poultry manure or a ready-made, potassium-heavy organic fertiliser is usually a better fit. The basics of what each nutrient actually does for a plant are covered in the guide to NPK fertiliser.

Nettle feed vs comfrey feed

Comfrey ferments in exactly the same way as nettles and works as nettle feed's natural complement rather than its rival. Comfrey's deep taproot pulls up unusually large amounts of potassium, which makes comfrey feed better suited to flowering and fruit set — precisely the stage where nettle feed's nitrogen does more harm than good.

Gardeners with room for both often run two separate buckets through the season: nettle feed for young plants putting on leafy growth, comfrey feed for tomatoes, cucumbers and squash from the first flower truss onward. If you only have space for one and mostly grow fruiting vegetables, comfrey tips the balance. If you mostly grow leafy crops and lawn, nettle is the better first choice.

Other ways to use the nettles

The strained plant material left over after brewing doesn't need to go in the bin. Add it to the compost heap, where it's already partway broken down and works well as a nitrogen-rich addition alongside drier material like leaves and cardboard. The basics of balancing wet and dry material in a compost heap are covered in the guide to composting for beginners.

Fresh, unchopped nettles also work as a mulch spread straight around the base of a plant or fruit bush. Lay down a thin layer, just a few centimetres deep, around the plant's base. It breaks down over a few weeks, feeds the roots directly beneath it, and helps hold moisture in the soil — a handy option on the weeks you don't have time for a full batch of liquid feed.

Does nettle feed keep aphids away?

It's often claimed that nettle feed keeps aphids off nearby plants, and some gardeners spray a weak mixture on vulnerable crops as a preventive measure. There's no solid evidence that it actually works as a pest deterrent, and it shouldn't be relied on as your only defence against an infestation. Think of it instead as a general tonic — a healthy, well-fed plant resists pests and disease better than a weak one, regardless of the cause.

If aphids are already a problem, dealing with them directly is far more effective. The guide to getting rid of aphids covers soap sprays, beneficial insects and other methods that are actually documented to work.

Is it worth the effort compared to bought fertiliser?

Financially, nettle feed is hard to beat — the raw material is free and all it costs is a bucket you already own. A bottle of liquid organic fertiliser typically runs to a fair amount of money and lasts an average vegetable patch a season, so the savings matter most if you're growing at scale or simply enjoy making things yourself.

The downside, smell aside, is that you never know exactly what you're feeding your plants. A bought fertiliser comes with a declared nutrient analysis you can rely on, while nettle feed varies batch to batch depending on how many nettles went in, how young they were, and how long fermentation ran. For anyone growing for the kitchen rather than competing for the biggest pumpkin, that variation rarely matters. Environmentally, you also skip the transport and plastic packaging, and you're putting a plant that would otherwise just get pulled and binned to good use. Many gardeners land on a middle ground: nettle feed as the main source of nutrition during the fastest, most wasteful stretch of early-summer growth, with a bought, precisely dosed feed reserved for demanding container plants or the more delicate flowering and fruiting stage.

Common mistakes

• Applying undiluted feed straight to the roots. The concentrate is strong enough to scorch sensitive roots. Always dilute according to the table above, even when you're in a hurry.
• Sealing the bucket airtight. Fermentation produces gas that needs to escape. A tightly sealed lid can crack the container or blow off unexpectedly.
• Continuing to feed heavily flowering plants. Nitrogen late in the season means more leaves but fewer, later fruit on tomatoes, cucumbers and similar crops.
• Harvesting nettles that have already set seed. The seeds survive fermentation and can sprout wherever you later water, giving you new nettles in unexpected places.
• Placing the bucket right next to the patio. The smell travels a long way on a warm day. Pick a spot well away from where people sit, ideally behind a shed or garage.
• Keeping the concentrate too long. After about six months the nutrients lose strength. It's better to brew a fresh batch than rely on one that's a year old.
• Relying on one type of feed all season. Nettle feed alone doesn't cover every stage. Switch to comfrey feed or a potassium-rich fertiliser once plants move into flowering, or you'll end up with lush leaves and a thin harvest.

Frequently asked questions

How long does finished nettle feed keep?
Strained concentrate keeps for around six months if stored cool, dark, and with a lid that isn't completely airtight. After that the nutrients lose potency, even though the liquid itself doesn't become unsafe to use. It's better to brew a fresh batch for the next season than rely on an old one.

Why does nettle feed smell so bad?
The smell comes from fermentation, where bacteria break down the plant material and produce sulphur compounds and ammonia along the way. It's completely normal and not a sign anything went wrong. To cut the smell, try the EM-and-molasses method described above, or simply site the bucket well away from any seating area.

Can you use dried nettles instead of fresh?
Yes, dried nettles work but produce a weaker, slower ferment since some nutrients are lost during drying. Plan to use roughly double the amount of dried material you would have used fresh, and allow a few extra days of fermentation time.

Is nettle feed dangerous for kids or pets?
Diluted nettle feed poured onto soil isn't toxic, but it smells and tastes unpleasant enough that most children and animals avoid it anyway. Keep the concentrate out of reach, since it's strong enough to irritate skin and eyes on direct contact, the same as any concentrated fertiliser.

Can you speed up fermentation?
Warmer temperatures, finely chopped material, and adding EM with molasses or a splash of liquid from a previous batch as a starter culture all speed things up somewhat. Even so, plan on at least 7–10 days under the best conditions — forcing it any faster leaves you with a noticeably weaker feed.

Can nettle feed be mixed with other fertilisers?
Yes, plenty of gardeners alternate nettle feed with comfrey feed, which is more potassium-heavy and suits flowering and fruiting plants better. Brew them separately rather than fermenting nettles and comfrey together, then switch between the two batches depending on what your plants need at the time.

Can you use nettle feed on indoor houseplants?
You can, but the smell makes it impractical indoors. Dilute extra weak, at least 1:15, and water outside or on a balcony where the odour can air out. Most gardeners reach for an odourless bottled liquid feed for houseplants for exactly that reason.

Do you need to test the pH of nettle feed before using it?
No, that's not necessary for ordinary home use. Nettle feed is mildly acidic after fermenting, but at the recommended dilution it rarely affects soil pH in any meaningful way. If you grow acid-loving plants, the basics of testing and adjusting soil pH are worth a look for your whole garden, not just for the nettle feed question.

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