I get about three batches a season out of a single comfrey plant, and I’ve never bought a bottle of liquid tomato feed since I put one in the ground. Comfrey’s a deep-rooted perennial that pulls potassium and other nutrients up from way below where your veggies can reach, and steeping the leaves in water turns that into a feed you can pour straight on. Here’s how I make mine.
What You Need
- A bucket or drum with a lid, 10 to 20 litres. Put it somewhere out of the way. The smell is not subtle.
- Comfrey leaves, packed down tight. About a kilo fills a 10 litre bucket.
- A brick or heavy stone to weigh the leaves down.
- Water. Rainwater’s better than chlorinated tap if you’ve got it, but tap water’s fine.
- Something to strain it through. An old stocking or a chux cloth works.
I cut leaves with secateurs rather than pulling them, since comfrey regrows from the crown fast and you can take another cut in three or four weeks.
The Method
- Pack the leaves into your bucket, roughly two thirds full.
- Put the brick or stone on top to hold everything under.
- Cover with water, leaving 10 to 15cm of space at the top.
- Sit the lid on loosely rather than sealing it. It ferments and produces gas, and I learned the hard way that a tight lid on a full bucket wants to pop.
- Leave it to steep. In my Dayboro shed that’s about three weeks in summer. Cooler climates take longer.
- Strain the liquid off into a clean container and compost the spent leaves. They’ve still got structure left in them, just not much left to give your feed.
You’ll know it’s ready when it’s gone the colour of strong tea and smells properly foul. That smell is the sign it’s working, not a sign you’ve stuffed it up.
If you’re in a cool or cold zone, budget four to six weeks rather than three. I’ve had a batch in a Hobart share house take closer to five. If you’re tropical or subtropical, check it from the two week mark. Heat speeds the whole process up and I’ve had mine ready in under three weeks through a Dayboro summer. Go by smell and colour, not the calendar.
How to Use It
The liquid that comes out is a concentrate, and it’s strong enough to burn roots if you use it neat.
- Dilute at 1 part comfrey liquid to 10 parts water for a general feed.
- Go to 1:15 if you’re feeding young seedlings or anything in a pot, where there’s less soil to buffer it.
- Pour it at the base of the plant, not over the leaves.
- Weekly during fruiting for the crops that want potassium most: tomatoes, capsicum, chilli, pumpkin, zucchini.
- Fortnightly is plenty for leafy greens, since they’re after nitrogen more than potassium and comfrey tea leans potassium heavy.
I keep mine in an old cordial bottle with a strip of gaffer tape and “NOT FOR DRINKING” written on it in texta, because it does look exactly like a bottle of iced tea and I don’t want to explain that mistake to anyone.
The Payoff
One plant, cut three or four times a season, keeps a decent-sized veggie patch in liquid feed for the cost of a bit of bucket space and your own patience. No bottle, no trip to the shops, and you’re not paying for water and packaging on a feed that’s mostly water anyway.
The only hard part is remembering which bucket in the shed is the comfrey and which one is just a bucket with a lid on it. Get a second comfrey plant going once the first one’s established. You’ll use more of this than you think.
