Helen Babbs explains how to make your own liquid feeds.

Whether you’re growing a large polytunnel full of tomatoes, or fruit trees in pots in a urban smallholding, there are times when your plants need a little extra nourishment in the form of a liquid feed. Most garden centres and catalogues offer a wide range of ready-to-dilute feeds for this, from the ubiquitous “Tomorite” to organic seaweed extract. But liquid feeds are just as easy to make at home, not to mention being much more wholesome for your plants, and completely free!

Home brew

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The basic method for making liquid feeds at home is to soak nutrient-rich material such as fresh manure in water, usually for 2-4 weeks. For this you’ll need a large water-tight container, any size from a plastic bucket to a water butt depending on how much feed you need to make. A wide top is easiest for filling, while a lid is essential to stop rain diluting the mix or any wildlife falling in and drowning. You can simply mix the solid material with the water, or put it into a hessian sack or onion net for ease of handling. The mixture can be rather strong smelling, so it’s best to set it all up well away from your house or outdoor sitting areas.

During the soaking time, the nutrients gradually dissolve into the water, ready for plant roots to take up. The feed liquid is then drained off and the solid residues emptied out and put on the compost heap. From a small bucketful, it’s easiest just to scoop the liquid out with a pot, but with larger containers fitting a tap at the bottom, like on a water butt, makes draining it out a bit easier. Once the liquid is collected, it will need straining to remove any solid lumps. I find either a coarse mesh kitchen sieve or a piece of fine chicken wire folded into a cone work well for this.

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Depending on how strong the liquid feed is, it may be used neat, or diluted like a proprietary liquid feed. If possible, it’s a good idea to keep a separate watering can for applying the feed, so no residues are watered onto plants which don’t need it. If you have any home-made liquid feed left over, it will always do the compost heap good too.

Liquid manure

One of the best “multi-purpose” home made feeds is “liquid manure,” made from fresh animal manure without too much straw.

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You need about 5 litres of manure added to 55 litres of water. Although measuring manure in litres sounds a little odd, I find it works quite well by just collecting the fresh manure into a 5 litre bucket, such as the ones sold as “calf buckets”. This ratio means the liquid feed can be used neat, or you can soak the manure in less water and dilute it before use. The mixture is left to soak for two weeks, then strained off and used straight away. Any type of animal manure can be used, although sheep manure gives the richest feed with a typical nutrient content of 0.8% nitrogen, 0.5% phosphorus and 0.4% potassium, along with a full range of trace elements. This is suitable for most plants, particularly in the leafy growing stage.

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A higher nitrogen animal-based liquid feed can be made from soaking the “daggings” or dirty offcuts of fleece from sheep or fibre goats. As these come mostly from the rump of the sheep, they have soaked up plenty of urine, which gives a good supply of nitrogen to the feed, along with a little potassium from the wool grease. I tend to use this liquid feed as a one-off drench for plants after putting down a straw mulch, to counteract any nitrogen robbery from the straw.

Compost tea

If you don’t have a suitable supply of fresh manure, a similar liquid feed can be made using well-rotted compost.

You’ll need the same proportions of 5 litres of compost in 55 litres of water, again soaked for about two weeks. This will typically be lower in nitrogen and a bit more variable than liquid manure, due to the varied material making up the compost. However, “compost tea” also contains the many beneficial micro-organisms from the compost, which will help make your soil healthier. Like liquid manure, the finished feed can be applied neat, or you can dilute it with an equal quantity of water to apply to young plants and seedlings.

Another compost based liquid feed can be made by collecting the thick brown leachate which drains from a worm compost bin or compost tumbler. This is similar in composition but much more concentrated than soaked “compost tea,” so needs to be diluted at a ratio of 1:10 with water before use.

Nettle soup

However troublesome a weed they may be around the smallholding, nettles make an excellent general purpose liquid feed, rich in magnesium, sulphur and iron.

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Young, spring-time nettles have the highest nutrient levels. They are supposed to sting less if cut and left to wilt for a couple of days, but I tend to simply use rubber gloves to collect them. The nettles should be soaked for two weeks, with about 1kg of leaves for each 10 litres of water. The resulting liquid is then diluted in 10-15 parts of water before using.

Comfrey extract

With their exceptionally high nutrient content, comfrey leaves make a potassium-rich liquid feed suitable for fruiting plants such as tomatoes.

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Comfrey extract can be made in a similar way to the nettle feed, with 3kg of leaves soaked in 45 litres of water. As each comfrey plant gives about one kilogram of leaves per cut, I tend not to measure but simply cut three plant tops. The leaves should be soaked for four weeks, and the liquid can then be used neat, ideally within a few days.

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Alternatively, comfrey extract can also be made “dry,” by packing freshly cut comfrey leaves into a bucket or other container, and weighting them down with a brick. If you tie a string round the brick, it’s easier to remove afterwards. After 3-4 weeks, the comfrey breaks down into a thick, black liquid, which can be drained off and stored in an open bottle for several months. It’s important not to seal the container, or the comfrey extract will ferment and may explode! As this extract is very rich, it needs to be diluted with 10-20 parts of water before use. For tomatoes, I add 0.5 litres to a 10 litre can of water and feed three times a week once the fruits start to develop.

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This article was first published in Smallholder magazine. For your copy subscribe here or buy from your local newsagent.