My fellow gardening pal, Nancy Abra, originally gave me stinging nettle for my butterfly garden because it’s a host plant for Red Admiral butterflies here in Ontario. A beautiful, ecological idea – and very thoughtful.  But as a newer gardener, what I didn’t realize is that stinging nettle has a reputation as a bit of a garden menace. It’s stingy, persistent and not exactly a polite plant.

Stinging nettle spreads through underground rhizomes – creeping stems that travel through the soil and send up new shoots. So while I planted it with lovely butterfly-garden intentions, the nettle had its own expansion plan and quickly started working on a small empire.

So I decided to chop some back. And since I’d heard plenty of whispers in the foraging and gardening communities about nettle being a useful plant to have around, I figured I’d do a little research and put my misbehaving nettle to work.

Stinging Nettle is often described as a “dynamic accumulator” – this is a super cool term used for plants that concentrate high levels of nutrients in their tissues.  When nettle leaves are steeped and fermented in water, some of those nutrients are released into the fermented liquid, creating a homemade plant feed!  Research shared by Cornell Small Farms found notable levels of phosphorus, boron, calcium, copper, manganese, potassium and magnesium in stinging nettle fertilizer.

This kind of fertilizer is most useful during a plants “vegetative growth stage”.  The vegetative growth stage is when a plant is building its green body (leaves and stems) before shifting energy into flowering, fruiting or setting seed.

How to Make Stinging Nettle Fertilizer

You’ll need:
Fresh Stinging Nettle leaves and stems
A bucket or large container
Water, ideally rainwater if you have it
A lid or something to loosely cover the bucket
Cheesecloth or a strainer

Method:
Place the nettle in a bucket, filling it about halfway.
Cover with water.
Put a loose lid on top. This helps keep bugs out but allows gases to escape as it ferments.
Let it steep for about 1 – 2 weeks, stirring occasionally.
When the liquid is dark and smells funky, strain out the plant material.
Dilute before using: roughly 1 part nettle fertilizer to 10 parts water.
Water around the base of leafy greens or young plants during active growth.

Note:  A gentle warning, this stuff smells!  Not like a “fresh herbal tea” but more like “a swamp joined a gym” type smell. But the your plants will love it!  Also remember that stinging nettle fertilizer is concentrated!  Dilute before using so your plants get a gentle nutrient boost.

References
Tyler, Ben, and Greta Zarro. “New Findings Further the Study of Dynamic Accumulators.” Cornell Small Farms Program,  April 2022.  https://smallfarms.cornell.edu/2022/04/new-findings-further-the-study-of-dynamic-accumulators/