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Dublin: 4°C Sunday 17 January 2021

GIY Comfrey: Grown for it's healing powers, comfrey is a great garden fertiliser

Comfrey sends its roots deep into the soil and brings up nutrients, most notably potassium, writes Michael Kelly.

Michael Kelly Grower

AS I KEEP my eye on the lush growth of the tomato plants, my thoughts turn to feeding these hungry plants. This is something that I will be doing every two weeks or so as soon as the plants start to produce fruit. Rather than buying liquid feeds, for some years now I have been making my own organic version by soaking the leaves of the comfrey plant.

Comfrey is a perennial herb with big, broad hairy leaves that produce small purple flowers. It has long been used as a feed by organic gardeners, particularly the variety “Bocking 14”, named after the town of Bocking in Essex which was the original home of the organic gardening research association, Garden Organic.

Nature’s fertiliser

Comfrey is a remarkably fast-growing plant and is one of nature’s great “miners” – that is, it sends its roots deep into the soil and brings up nutrients, most notably potassium, from deep in the subsoil.

It is this nutrient in particular which will be of benefit to the tomato plants, and in fact all fruiting vegetables in the garden (eg pumpkins, courgettes, squash). The basic idea of making a comfrey tea is to harvest leaves and soak them in water for about a month.

This potassium-rich “tea” is then applied as a feed to fruiting plants. I use a shears and literally cut the plant down to about 2 inches from the surface of the soil. Use a pair of gloves, as the leaves are a little prickly. You can harvest mature comfrey plants 3-4 times each year. It grows back quickly and can be cut again about a month later.


You should be able to source the plants from a good garden centre and then plant them out about 2ft apart. They will tolerate a shady, even damp spot in the garden. Mine are thriving in a corner of the garden behind the tunnel.

Keep the bed well watered until the plants get established and don’t harvest leaves from it in the first year. Strangely, comfrey doesn’t seem to be able to mine the nitrogen very well that it needs for itself, being a fast-growing leafy plant (similar to a brassica).

I generally mulch the plants when they die back in the autumn with lawn clippings. In addition to making a comfrey tea (see below) you can also add comfrey leaves to the compost heap where they will accelerate the de-composition of your heap and add potassium.

You can also use the leaves as a mulch, putting a layer of leaves around a plant where they will break down and release their nutrients more slowly. I’ve heard of people putting comfrey leaves in a trench when planting potatoes and also planting comfrey underneath fruit trees as a companion plant.

The Basics – Comfrey tea

There are two ways to make a comfrey tea. You can either make a concentrated tea that will have to be diluted, or a ready-to- use version.

1. Concentrate

Harvest comfrey leaves and shove them in a bucket with a lid. Weigh the leaves down with a brick or something else heavy. Drill a hole in the base of the bucket and place a container underneath.

As the leaves rot down a black liquid will start to drip down from the bucket into the container. This is your comfrey feed. Dilute one part comfrey liquid to 15 parts water.

2. Ready to Use

Harvest your leaves and put them in a bucket. Fill the bucket with water until the leaves are covered. Cover with a lid and leave for 3-4 weeks. This type of tea is ready to use without diluting.

Recipe of the Week – Spanish Tortilla

shutterstock_459517750 Source: Shutterstock/carpaumar

This week saw our first new potatoes from a January-sown crop in the polytunnel. It’s one of my favourite harvesting moments of the entire year. You don’t want to do anything fancy with the first harvest of new potatoes – a sprig of mint in the sauce pan when boiling them and then lots of good Irish butter and Bob’s your uncle.

It’s a tradition in our house that I eat so many on the first sitting that I get a pain.

For the second, third and subsequent harvests it’s time to get creative and keep the delicious spuds centre stage. This classic tortilla recipe from The Natural Cook (Tom Hunt) does exactly that. Serve as a generous lunch or light dinner with a salad of peppery green leaves. Serves 4.


  • 350g new potatoes, washed
  • A splash of olive oil
  • A pinch of sweet paprika
  • Salt and black pepper
  • 2 onions, sliced
  • 2 garlic cloves, roughly chopped
  • 4 eggs, lightly beaten


Cut any large potatoes in half so all the pieces are roughly the same size. Bring to the boil in a saucepan of salted water, then reduce the heat and simmer for 8-10 minutes, until just soft.

Drain and cool, then dry, cut into cubes and fry in a good glug of the oil over a medium-high heat for 10 minutes. Keep turning to ensure a good all-round, golden, crisp skin.

When ready, sprinkle with paprika and salt and set aside. Slowly saute the onions for 15-20 minutes in light olive oil until they are very soft. Add the garlic and fry for another 2 minutes.

Add the onions to the potatoes and allow the whole lot to cool. Now add the eggs and mix, crushing the potatoes a little as you do so. Season with salt and pepper.

Heat a deep 15-20cm frying pan with a good splash of the oil. When it begins to smoke, pour in the egg mixture. Reduce the heat to its lowest and cook for 4-5 minutes, shaking the pan from side to side to prevent it from sticking.

When it is cooked halfway through, it is ready to turn. Flip the tortilla onto a large plate. Return the pan to the heat and slide the tortilla back into the pan, raw-side down. Shake from side to side again to make sure it isn’t stuck. Using a wooden spoon, tuck the rough edges underneath to make them rounded, then cook for a further 5 minutes.

Slide onto a plate and allow to cool.

Michael Kelly is founder of GIY and GROW HQ. 

Click here for more GIY tips and recipes.


About the author:

Michael Kelly  / Grower

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