Turn Your Weeds into Nutrient-Rich Fertilizer

Joanne Brown
Frederick County Master Gardener

It’s spring, and gardeners everywhere are spending hours pulling up all sorts of unwanted plants — also known as weeds. But what is a gardener to do with all of the pulled-up weeds?

Turn them into nutrient-rich fertilizer!

Liquid fertilizer—also known as weed tea, but don’t drink it!—is easy to make and will give your garden a boost of nutrients, including nitrogen, phosphorus, potassium, magnesium, boron, copper, manganese, sulfur, iron and silicon. You can safely use weed tea on both flower beds and vegetable gardens, either by pouring it on the soil at the base of the plants, or by spraying it on the leaves.

So-called weeds, especially those with very deep roots such as dandelions, have mined valuable minerals and other vital nutrients from the soil and store the nutrients in their roots and leaves. When you pull up these weeds and simply throw them out (not wanting to add them to a compost pile because the weed seeds are still viable), you toss out the minerals and nutrients as well. Turning the weeds into liquid fertilizer returns the nutrients to the soil. It is recycling at its best.

All weeds are candidates for liquid fertilizer, but we caution against using poison ivy, poison oak, or poison sumac.

Making Weed Tea

Turning weeds into liquid fertilizer is rather easy.

  1. Get a large bucket or other container with a lid.

  2. Put the pulled-up weeds (including both roots and leaves) in the bucket.

  3. Add water. Put about 8 cups of water in the bucket for every pound of weeds.

  4. Cover the bucket with a tight-fitting lid.

  5. Leave the bucket for 2 to 4 weeks.

  6. Stir it every week or so. But be forewarned — it isn’t going to smell very good—the fermentation process can be smelly, for sure. Try to think of it as having an earthy, agricultural aroma! And try not to get any of this concentrated concoction on your hands or clothes. It will stain.

  7. Strain it using cheesecloth (or even pantyhose!). The liquid is what you will want to use on your garden; the solid mass of fermented weeds may still contain some viable weed seeds, so you will want to discard it. After you have strained the liquid, it is done.

  8. Dilute it before using, at the rate of 1 part weed tea to 10 parts water. Then pour it on the soil at the base of your plants. To use it as a fertilizing foliar spray, dilute it until the color of the liquid is like a weak tea. You can also pour it on the base of your vegetable plants, but don’t spray it on the vegetables that are ready to be harvested.

Perhaps a better way to make it—a method that requires no straining—is to put the weeds in a permeable sack (tied at the neck), and put the sack in a large bucket of water (enough water to cover the sack of weeds). Let it sit for 2 to 4 weeks, adding water if necessary. You can also add additional sacks of weeds, making this method a recipe for ongoing weed tea production.

You can also add aged manure or herbs to the bucket, along with grass clippings and pruned-off plant parts. They all contain nutrients that can be recycled back into the soil through this process. It’s best to use the weed tea during the same season you produced it, the quicker the better.

People have been gardening for thousands of years, and did not always have manufactured fertilizers available for purchase. They used what they had available—including weeds— and made their own fertilizer. Making liquid fertilizer from weeds is a back-to-basics way of returning the nutrients in weeds to the soil. What could be easier?

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