Plant Feed Preparations

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The Haws watering can in action, designed to simulate natural rainfall. 

In this chapter we get down to the actual detail of preparing feeds by the traditional steeping method introduced in Chapter One. A number of techniques will also be introduced such as extraction methods for comfrey and the steps you need to take to prepare kelp meal. We will be applying some important resources that are world renowned for their fertility enhancing qualities. We will also be incorporating some plants that have fallen out of the attention of the mainstream but have a history of usage, such as yarrow. Some of the plants you may have come across are seen as weeds, but have surprising and useful roles for the home brewer.

As discussed in Chapter Two, plants uptake substantial amounts of nitrogen (N), potassium (K) and phosphorus (P) so it is understandable that they form a large proportion of both conventional fertilisers and organic feeds. Secondary calcium (Ca), sulphur (S) and magnesium (Mg) trace elements are also important as previously outlined, but are only needed in smaller volumes. Many of the plants described in this chapter have multiple benefits for the organic grower such as refuges and food stores for beneficial insects, which will be noted as we go along.

An important point is that a resource may not hold all the necessary nutrients to give your hungry tomato or pumpkin a boost, so with this in mind some preparations use combinations of plants and composts.

If you follow good organic practice for a basic level of soil fertility, many of the concerns with nutrients and their availability have been addressed in a holistic way that bypasses the necessity of tinkering with the finer details. In Chapter Two we introduced how to assess what may be lacking in your soil and in Chapter Three we looked at the cycles of some of the most important nutrients. In this chapter we hope to replenish many of the nutrients removed by harvesting and other causes with various preparations to furnish your plants with what they need, but before we proceed, we need to consider some issues with chlorine.

Chlorine issues

This only applies to people using tap water; if you are using rainwater, which is recommended, you can discount this section entirely.

Chlorine is used in domestic water supplies to kill pathogens within pipes. The amount of chlorine in drinking water varies and for public health must be between 0.5 ppm and 2 ppm.1 Laboratory studies indicate that even at these levels it can disrupt or kill some beneficials. For instance it was found that rotifers (beneficial) were stunned at 2 ppm of chlorine.2 A small amount of chlorine in your feeds will not be disastrous and it is an essential element to most organisms in trace amounts, but why have damaging amounts there when it can be easily removed?

The simplest solution is to pour out your water, leave it open overnight and agitate it in sunlight as the UV rays will help the chlorine to disperse. The ‘aquarium method’ of adding various potions to your water to disperse the chlorine is not recommended because it introduces chemicals to your brew with uncertain effects and is something of an overkill.

A more challenging problem related to chlorine is chloramine. This substance does not disperse when exposed to air like chlorine. There are two methods, one costly and one free, but not quite so effective. The costly answer is to pass your water through a carbon filter. The process is as simple as buying the product and pouring it through your filter. Some may consider the use of carbon filters as overly elaborate and unnecessary because the chloramines work by attaching themselves to organic matter,3 so if chloramines come into contact with vermicasts or compost this substance will be removed by a small sacrifice of living organic matter. Hence the more cost effective method would be to mix in some organic matter then strain the solution. For the purist this is not acceptable; they want the best possible environment for their microherds to thrive in, but realistically no one should lose sleep over their preparation being contaminated by chloramines.

Comfrey tea

An important variety is Russian comfrey or Bocking 14, which unlike the wild plant does not set seed. Comfrey (Symphytum officinale) is a perennial and grows up to 1.5m. It is rich in phosphorus and potassium so it is very good for fruiting plants such as tomatoes, cucumbers and peppers. Comfrey is also a useful source of manganese, calcium, iron and cobalt.4

Comfrey (Symphytum officinale) in flower. 

It is one of the most popular support plants for organic gardeners and with good reason. Comfrey makes an excellent forage for bees and can be used as a top dressing and as a compost activator. It also makes an excellent barrier against encroaching weeds and its size offers possibilities as a wind shield. Comfrey is known as a dynamic accumulator because it can draw nutrients from deep within the soil.


Steep 1kg of comfrey leaves in a sack with 10 litres of water. Cover but do not seal, stirring every couple of days. Leave for 10 days. Dilute 7 parts water to 1 part feed for foliar applications. For root feeds it can be used undiluted using a container sunk into the ground.

Concentrated comfrey extract

As an alternative to the steeping method an extract can also be prepared which does not require any water. It can be stored for up to six months and does not smell as pungently as the steeped comfrey. You simply need a container with a small hole in the base and a collecting vessel as shown in the diagram above. It is important to cover the vessel to protect it from UV light or it will compromise the breakdown process. It has been known to use an old bath with a carpet thrown over for this method.

Diagram of set-up apparatus for comfrey extract 

To get things started, stuff comfrey leaves into the hole and then add more leaves and press them down well. Place a collecting vessel below the hole. Within a few days the dark comfrey extract will start to drip into the vessel.

Leave to drip into the collecting vessel for 14 days when it can be sealed. For foliar application dilute 10 parts water to 1 part feed. For root feeds it can be used 2 parts water to 1 part feed.

More from Compost Teas for the Organic Grower:

Cover courtesy of Permanent Publications

Excerpted with permission from Compost Teas for the Organic Growerby Eric Fisher, published by Permanent Publications and distributed in the USA by Chelsea Green Publishing, 2019.

Mother Earth Gardener
Mother Earth Gardener
Expert advice on all aspects of growing.