How to make comfrey tea – organic plant feed for free

Comfrey is an incredible plant as it tolerates nearly all soil conditions and will live in both full sun and shade. Meaning you can grow Comfrey pretty much anywhere no matter what garden soil you have. Comfrey has long been used to help activate compost heaps, brew liquid plant food and help improve vegetable beds as a soil improver. It really is a wonder plant for any garden!

Comfrey can be used to make a liquid plant food or tea. Enabling you to feed your garden fruit, vegetables and plants without spending a penny after buying the perennial plant (meaning it comes back year after year) Comfrey.

Let’s take a closer look at why Comfrey is such a fantastic garden plant and fertilizer.

What is Comfrey?

Comfrey is a plant from the Symphytum genus of flowering plants in the borage family know as Boraginaceae. It’s a native herb here in the UK and has a variety of medicinal and nutritional uses. Particularly in animal feed. It can live for up to 20 years and is a herbaceous perennial. Ie it dies back each winter and regrows each spring.

It’s not overly vigorous but you want to leave at least 60-90cm between each plant to give them space to grow. I have 5 Comfrey plants here for my acre and a half of a garden. However, most small gardens only need one plant in my experience to make enough plant food for each year.

Comfrey Bocking 14 growing next to my compost heap – planted just over a year ago

Comfrey used for fertiliser tea is sterile, meaning it’s been bred for certain characteristics with the exclusion of setting seed. You need to propagate Comfrey by division or by purchasing small plants that have already been grown.


Is Comfrey safe to eat?

There is also some caution about liver damage after a study in rats that were given large amounts of Comfreys alkaloids that caused the rats to suffer liver damage. However, a number of holistic groups claim that eating small amounts of comfrey to be harmless, it’s even been used as an additive or supplement in the past!

It’s never been replicated or further studies in humans. So it goes to say take care whenever eating herbs with unknown side effects. This guide is for use in plant feed which is harmless to humans/animals and has been used for centuries.

How strong is Comfrey Tea compared to other plant feeds?

Comfrey is known for its ability to store up huge amounts of nitrogen, phosphorous and potassium (also known as N:P:K). These are the 3 macronutrients that plants rely on for healthy growth, fruiting/flowering and disease resistance. It also produced high yields with very few care requirements. Ie its a super unfussy plant!

Comfrey Bocking 14 basically taps into nutrients locked away in the depths of your soil allowing you to then use them. When you compare to well-rotted manure and compost you can see below the insane levels of Potassium (K) in Comfrey tea as a comparison.

Material Water
(N) %
(P) %
(K) %
Carbon: Nitrogen Ratio
Farm Yard Manure 76.0 0.64 0.23 0.32 14 -1
Wilted Russian Comfrey 75.0 0.74 0.24 1.19 9.8 – 1
Indore Compost 76.0 0.50 0.27 0.81 10 – 1

The above were the findings in trials from L D Hills Book ‘Comfrey: Past, Present & Future table extract from Just check out the K or potassium/potash column to see how much richer it is!

What is Comfrey ‘Bocking 14’?

Comfrey ‘Bocking 14’ is a variety that was cultivated by L D Hills founder of the HDRA (Henry Doubleday Research Association) a horticulturist and writer. He wanted to breed a form of sterile Comfrey (meaning it doesn’t waste effort setting seeds where valuable nutrients would be expelled) that could be used to extract high levels of plant nutrients from the soil. You can read a fascinating set of facts on this website all about the background of Comfrey.

It’s a customised version of Comfrey taking the very best bits of different breeding examples to create a ‘variety’ for specific traits. In this case nutrition and macronutrient extraction from the soil using the Comfreys deep taproots.


Equipment needed for Comfrey Tea

You’re going to need the following to make Comfrey tea:

  1. Comfrey Bocking 14 growing in your garden or a friends

2. A airtight container to hold the leaves and liquid


3. Sharp secateurs to cut the Comfrey with


4. Gloves to protect your hands from their rough leaves


5. A pen to label the container


How to make Comfrey Tea

Comfrey tea couldn’t be easier to make. Though it does take a bit of patience and also compromise given how bad it can smell when it’s brewed!

However, no other fertilizer in trials comes close to providing the same amounts of macro nutrients so it is worth the wait and the smell! There are less smelly methods but I find this the easiest without spilling it or needing to make careful dosage rates for dilution. I think this is a great method for beginner gardeners to create comfrey tea and avoid overfeeding their plants with the wrong dilution rates!

Step 1 – Cut your Comfrey

Cut back one of your Comfrey plants leaving 1/4-1/3 at the base so it can regenerate


Step 2 – Strip the leaves

Wearing gloves stip off the leaves of the cuttings and place the stems to one side, we will reuse those later

Place the leaves into the container one on top of the other fitting as many tightly in as possible. Leave a small gap before the lid so it doesn’t spill over and is easier to decant.


Step 3 – Fill the container with water

Fill up with water to cover the leaves depending on the size of the container.


Step 5 – Seal and label

Place the air tight lid onto the mix and make sure you label it. So you and others know what lurks inside!


Step 6 – Wait 3 to 6 weeks for comfrey tea to brew

Wait 3-6 weeks until the liquid turns brown and smelly. The leaves should have turned into a thick goop by now. If not, return the lid and leave for another few weeks.


Step 7 -Sieve off the comfrey tea

When your Comfrey tea is ready sieve off the liquid into another container, removing all the goop and debris. This goop can be put on the compost bin or into flower beds.

Then dilute at a ratio of 1:10. Your tea is then ready to be applied to your plants and flower beds. Water onto the base of any plants you want to feed!

How to dilute comfrey tea?

With this method, you want to dilute the brown liquid 1 part comfrey tea to 10 parts water. This should provide you with the perfect mix. Try to avoid overfeeding any plants, it’s not good for them and be wasteful. Better to make a weaker fertilizer than one that’s too strong it does more harm than good.

Look to feed hungry plants like Roses and Tomatoes once a week when in full growth or fruiting. This is also a great feed for hungry hanging baskets and containers with annual plants (ie those bedding plants and similar that just live for one growing season).

What else can I use Comfrey for?

Remember we talked about saving those stalks when we cut back the Comfrey? Well, they can be used in your compost bins as an activator or chopped up and added directly to veg beds as a top dressing mulch. As they break down all the other good bits from them will be absorbed by the soil and ready for your plants to benefit from!

There are a few other handy uses when you’re growing Comfrey Bocking 14:

  • Use cut, damaged or bruised comfrey leaves in your compost heap/bin. The decomposition of the Comfrey cuttings will encourage bacterial and cause the heap to heat up and speed up the composting process known as acitvation.
  • Use as a mulch in the garden. Chop up comfrey leaves roughly as use as a surface mulch around plants. A shredder can be helpful for this. This will slowly break down to provide nutrient. Mulches are great to keep in moisture, feed plants and help control the emergence of weeds.


Comfrey is an absolutely fantastic plant if you want to make your own plant food for free or you simply want to stop relying on mass-produced fertilizers which can be bad for the environment. Even the smallest garden space could make way for 1 comfrey plant somewhere near a compost bin or shed that should make enough comfrey tea to last all season.

So why not give Comfrey tea a go and let me know on my Social Media channels how it’s gone for you?


Happy Gardening!

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