Comfrey is one of my favourite plants and I believe every single gardener should grow Comfrey. It’s a herb which has been grown by gardeners for decades and sometimes known as Knitbone. This name originated from the fact that this plant was used as a remedy to heal bones if they were broken.
In this article we will explain why you should grow Comfrey and also how to grow it.
Why You Should Grow Comfrey
The main reason is that Comfrey can help you to provide your garden with important nutrients. Comfrey is a deep-rooted plant. Its deep root system is very extensive in general.
And because of this, Comfrey is capable of gaining its required nutrients from deep down the soil. The nutrients collected by the comfrey roots are stored in its leaves. When their leaves fall or are cut, the nutrients become easily available to other plants too.
This herb is appreciated for the fact that it does not lock in nitrogen. It is also a good source of potassium and phosphorus.
While you can’t eat Comfrey, as it can be harmful, you can use it to feed other plants in your vegetable garden. And this means you can increase your yield without having to buy commercial fertilisers.
If you grow Comfrey in your garden, you will also give pollinators and beneficial insects a reason to come into your garden. Pollinators will ensure that vegetable plants that need pollinating to produce fruit will get pollinated.
Beneficial insects, such as hoverflies or ladybirds, will keep pests in your garden to a minimum. They will eat pests such as aphids and whitefly.
You can use comfrey in a variety of ways to benefit the plants in your garden:
- Make your own liquid fertiliser
- Make ‘Comfrey tea’
- Use as mulch
- Use as compost activator
- Use as feed for chickens and other livestock
- Provide food for wildlife
As you can see there are a lot of uses for this plant, which makes it worthwhile to grow Comfrey in your vegetable garden.
Which Comfrey Variety Should I Grow?
If you want to grow Comfrey in your vegetable garden, you have to make sure that you choose the right variety.
Common Comfrey or wild Comfrey is self-seeded and will, once established, spread quickly. It can take over your garden, as it is very difficult to control once securely in the ground.
The most commonly grown variety of Comfrey is called Bocking 14. It is a sterile variety, which is much easier to control. A sterile plant can’t produce fertile seeds, so there is no risk of the plant spreading uncontrollably.
It is planted by taking off sets from the parent plant and planting root cuttings that way. If you want to plant Comfrey, it is important that the plant you have chosen to get the offsets from is very strong and mature. Using a spade, the crown should be removed and split into more pieces.
The plant from which this crown is taken will recover soon too. These off sets can be sown and grown into new plants.
You can get Comfrey root cuttings from garden centres or online. If you want to grow Comfrey from seed, you have to be aware, that you can only grow common Comfrey that way. Because the sterile variety does not produce viable seeds.
Any Comfrey seeds you can buy will therefore be wild or common Comfrey.
How To Grow Comfrey
Now that we have talked about why every gardener should grow comfrey and which variety to grow, let’s look at how to grow this wonder plant.
First you have to choose the location for your comfrey patch. This plant can grow for 20 years and once it’s established it is difficult to move it, because of its deep roots. So make sure you are happy with the spot you pick.
In terms of the best location, comfrey thrives in full sunlight, but will do equally well in partial shade.
Comfrey is not difficult when it comes to soil, as it will grow in any soil type, as long as it is deep enough for the root system. However, Comfrey plants will thrive in rich soil.
To prepare your comfrey patch, mix in organic matter, such as well-rotted manure, to improve the condition of your soil. The best time to do this is autumn.
Plant your comfrey cutting mid to late spring and space them between 60 – 90cm (24-35in) to give each plant the space it needs. Give them a good soak after you have planted them.
Caring For Your Comfrey Plants
Comfrey is a very low maintenance plant, that is also very hardy. Because of its extensive and deep root system, it can get water and nutrients from places that other plants can’t reach.
Therefore, there is not much you need to do. However, it will increase your crop, if you feed mature plants occasionally. Putting grass clippings on the soil will work very well. Manure and compost will also work, but I like using grass clippings as they are free.
To improve your yield, remove the flowering stems in the first year. This will encourage the plant to focus on the leaves in the next year.
The comfrey leaf is what most gardeners are after, as it can be used in multiple ways to help other plants in the garden. Be careful when harvesting, the comfrey leaf is hairy and can irritate the skin. Wear gloves to protect your skin.
Comfrey plants that have been planted in spring should produce their first crop of comfrey leaves towards the end of summer/beginning of autumn.
After the first year, you can harvest the leaves in early summer and again in autumn.
Cut the leaves from the base of established plants, about 50cm (2in) above soil level.
As already mentioned, there are several uses for comfrey leaves. Here we describe some of them.
Using Comfrey Leaves In The Vegetable Garden
Gardeners grow Comfrey because it’s a plant that contains many nutrients such as nitrogen and potassium. These nutrients can be extracted to benefit your vegetable plants.
Liquid Comfrey Feed
Any liquid feed made from Comfrey will be high in potassium. This makes it ideal for feeding potatoes, tomatoes, cucumbers and many more plants. Thereby increasing your yield without having to buy expensive fertilisers.
And making your own liquid comfrey feed is very easy. All you need is a bucket with a lid, water comfrey leaves and some old bottles.
These are the steps to take:
- First harvest your comfrey leaves and remove the flowers and stems.
- Chop them up roughly and put them in your bucket and put a stone on top of them.
- Then add water to the bucket: for every 1kg of leaves, add 15 litres of water.
- Then put the lid on.
- As the leaves break down, they will release their nutrients. Check on the progress every couple of weeks. You will notice the water becoming brown and smelly.
- After 4-6 weeks, your liquid Comfrey feed will be ready.
- Empty the bucket on your compost heap.
To use your homemade Comfrey fertiliser, just put the liquid in a watering can and water as normal. You don’t need to dilute it, as you have already put water in at the beginning.
Use this liquid fertiliser for vegetable and fruit plants that have started to set fruit. You can use it on a variety of plants, such as potatoes, tomatoes, cucumbers, etc. This use makes it a good idea to grow Comfrey.
Concentrated Liquid Comfrey Fertiliser
You can also make a liquid concentrate, that you can store in your shed. It’s just as easy as the liquid feed. You will need a stone, a bucket with a lid, comfrey leaves and old bottles.
Here is what you need to do:
- Harvest the comfrey leaves as described above.
- Put them in the bucket and add a bit of water, not much though.
- Then put the stone on the leaves to weigh them down.
- Close the lid and wait.
- Check every few weeks as the leaves will release a brown and smelly liquid.
- Strain this liquid into the bottles and store in a cool, dry place, such as a shed.
- Keep topping up with fresh leaves until you have enough liquid concentrated Comfrey fertiliser for your needs.
- When you want to use it, dilute it with water. Depending on how dark the liquid is you need to dilute it more or less. If the liquid is fairly light, dilute it at a ratio of 1:10 (one part Comfrey fertiliser and 10 parts water). If the liquid is very dark, use a ratio of 1:20 instead.
- Use the diluted fertiliser as you would a commercial liquid feed for veggies that have started to flower.
Comfrey leaves work extremely well as mulch. Just chop them up roughly and cover the soil and cover with grass clippings. As the leaves decompose, they will release all their nutrients into the soil.
Growing Tip: I like to chop up the leaves more finely and add a layer to pots after I have planted young plants. This gives them the nutrients they need to grow strong and healthy.
Activate Compost Heap
If your compost heap is a bit slow, you can use Comfrey leaves to speed up the process.
Because the leaves are so rich in nutrients, it does the same as manure would do. Just put a layer of Comfrey leaves on the compost heap and cover with grass clippings. This will activate your compost in no time.
You can also add the leaves to a leafmould pile to add more nutrients.
If you grow Comfrey in your garden, it can also benefit your houseplants. And it’s so simple to make.
Just keep some Comfrey leaves back when you harvest them in autumn and dry them. You can hang them up in the shed, for example.
Once they are dried, crumble them into a jar with an airtight lid. Then you use them like tea.
Put about a handful of dried crumbled comfrey leaves in a jar and add about a litre of water. Shake well and let infuse overnight. Then strain out the leaves and water your houseplants with it.
This will give them the nutrients they need, especially over winter when a lack of light and heated air can be a challenge for them.
Finally, bees, especially some bumblebees, and other insects, love Comfrey. So, if you grow Comfrey, you will attract these useful insects to your garden.
And as you provide them with food, they will in turn pollinate your plants. Everybody is happy!
Slugs also love cut up Comfrey leaves, not the plant though, for some reason. So you can coax them away from your seedlings by putting heaps of chopped up Comfrey leaves around your garden.
This way, the slugs get a tasty meal and leave your veggies alone.
Now that we have shown you how useful it is to grow Comfrey in your garden, you will surely be keen to create your own Comfrey patch. Happy Growing!