How to Make Homemade Comfrey Fertilizer in 8 Steps

Comfrey has long been known as a multifaceted plant in the garden, with some even dubbing it a “miracle” plant. This borage-family herb has a deep root system that pulls up nutrients from far down in the soil profile, accumulating the minerals and fertility in its roots and leaves. When used as mulch, compost, or homemade fertilizer, all of the nutrition inside comfrey becomes available to your garden crops.

If making fertilizer sounds daunting to you, rest assured that the process is as simple as making tea. Follow these quick steps to turn comfrey leaves into a homemade liquid fertilizer to boost plant growth and enhance soil health. 

What is Comfrey Fertilizer?

Comfrey fertilizer is a liquid “tea” or extract of Symphytum officinale leaves that is steeped in water and applied to garden soil or potted plants to boost fertility and minerals.

As a proven dynamic accumulator plant, this species naturally collects and retains bioavailable plant nutrients from the soil using its deep taproot. Namely, the leaves are high in potassium, calcium, and phosphorus. You can also add comfrey leaves to your compost pile to speed up decomposition and improve nutrient levels in the final amendment.

Benefits of Comfrey

The key garden benefits of Symphytum officinale are not limited to fertility. This amazing plant can:

8 Steps to Make Homemade Comfrey Fertilizer

Making your own plant food can be as simple as cutting back the leaves of this herb and tossing them in a bucket of water, then pouring it on your crops a few days or weeks later. But if you want to enhance the nutrient composition and availability of the liquid plant food, follow these steps to properly ferment a comfrey tea and dilute it as the perfect all-purpose plant liquid.

Plant Comfrey

If you aren’t already growing this herbaceous perennial plant, you will need to get some started in your garden. It is very fast-growing and low-maintenance, so don’t be afraid to toss seeds or crown divisions in an unused sunny or partially shaded corner. 

You can plant Symphytum officinale any time during the frost-free season, but it’s best to establish your patch in the spring. As long as there is ample moisture, the hardy perennial can adapt to almost any soil type or climate. In the northern areas of North America where the plant is invasive, grow it in a container.

Cut Leaves Above Soil Surface

Once plants are sufficiently established with several large leaves, you can begin harvesting the above-ground parts to make fertilizer. Be sure to wear gloves! This species has many stiff irritating hairs. 

Harvest a big bundle of leaves that will fill your bucket about three-quarters full. You don’t need to be super precise about the measurements.

Cut foliage freely; this hardy perennial doesn’t mind regular cutting back, as it regenerates quickly. Just be sure to leave 2-3 inches of growth above the soil surface where new foliage can develop. In container plantings, be more cautious about harvesting too much from young plants.

Bruise Leaves and Place in Bucket

Cracking and bruising the foliage helps it break down into liquid fertilizer more easily. You can bend and crumble them as you place them into any size bucket. I like to use a five-gallon bucket with a handle and lid that is easy to cover and move. You can add extra bruised leaves into your compost pile as a decomposition accelerator.

Press and Cover With Water

Push the foliage down into the bucket and fill with enough water to fully cover them. Cover the container with a lid and leave in your garden shed, garage, or shady spot in the garden. 

The fermenting fertilizer can put off a pretty strong smell, so don’t keep the bucket anywhere it might bother you. Keeping the lid cracked will allow for some oxygenation. Some growers prefer to insert a submersible fish-tank pump to keep the liquid aerated like a compost tea.

Wait Two to Six Weeks

The amount of time you leave your bucket to ferment depends on temperature, humidity, and the potency you desire for the final product. Shorter time frames will yield a less potent but less stinky liquid. A longer fermentation period will create a stronger liquid comfrey fertilizer with a smelly aroma, but it will add more nutrients to your plants.

Strain

Use a strainer or bucket lid to separate the steeped leaves from the brown fertilizer liquid. Pour the final product into another container or a watering can that makes it easy to distribute. The remaining leaves can be tossed in the compost to decompose.

Pour On Garden Soil

Your completed homemade comfrey fertilizer is far more valuable than the smelly brown liquid it appears to be. You can add it to a spray bottle to use as foliar feed for small plants, but I find it much easier to dump the liquid by the cup-full around your crops. Pouring it near the root zone ensures that your desired crops take up the nutrients; avoid pouring the liquid in the center of bare soil where weeds can snatch the fertilizer to boost their own growth. 

Some gardeners dilute the liquid with more water before applying to young plants or seedlings. This step is optional but may be desirable for potted and indoor plants that you don’t want to stink up the house. 

Add Remainder to Compost Pile

Any remaining sludge or residue at the bottom of the bucket can be added to your compost pile and rinsed from the bucket. Make homemade comfrey fertilizer as often as you’d like and see if your plants begin growing faster and healthier after the nutrient-rich additions.