A liquid organic fertilizer works for both vegetable and ornamental plants. Make it at home by combining store-bought organic fertilizer or yard waste with water, and allowing it to sit for three days to extract the nutrients into the liquid. Before drenching the soil around your plants with the rich solution, dilute the extract so it doesn't burn plant roots.
Choose the Container
The container you choose for making organic fertilizer can be any size but must hold water without leaking. It can range in size from as small as a 4 ounce jelly jar to as large as 32 gallon trash can. The main consideration when choosing a container is liquid organic fertilizer must be used within 48 hours after it is finished. So choose a size appropriate to the number of plants you have to feed so no fertilizer is left over.
Select the Organic Material
Plants need nitrogen, phosphorous and potassium to be healthy and strong. Grass clippings, stinging nettle (Urtica dioica) which grows in U.S. Department of Agriculture plant hardiness zones 3 through, commercially produced granulated organic fertilizer or finished compost provide these elements in homemade organic fertilizer. You need only add one type of organic material. Something to consider is that grass clippings and stinging nettle have been shown to be rich in nitrogen and potassium. Stinging nettle also supplies ample amounts of calcium and iron, which plants need for strength and to prevent yellowing. For vegetables, choose a granulated organic fertilizer that has an N-P-K ratio of 3 parts nitrogen, 1 part phosphorous and 2 parts potassium listed on the label, such as 6-2-4 or 3-1-2.
How much organic material and how much water you add to the container depends on the type of organic matter you use. To make 5 gallons of liquid organic fertilizer using granulated organic fertilizer, add 5 cups of granules to 5 gallons of water. To use mature compost, mix 5 pounds of compost with 5 gallons of water. For stinging nettle or grass clippings, pack enough plant material in a 5 gallon bucket so it is one-fifth full. Transfer the plant material into a larger container and fill with 5 gallons of water. No matter what type of organic material you use, stir the liquid immediately after combining ingredients, then place where it won't be exposed to extreme heat or cold, such as in a garage.
Let It Sit
Liquid organic fertilizer takes three days to leach nutrients into the water. Stir it once per day. Use the mixture within two days after it is finished because it will ferment and breed bacteria that may be harmful to you or your plants.
Strain, Dilute and Use
To use the liquid fertilizer, separate the water from the granules or plant material and dilute it before feeding plants with it. Do this by placing cheesecloth, or another loose-weave cloth, over a clean 5-gallon bucket and fastening it to the bucket with twine. Pour the mixture through the material. Dilute the extract with fresh water, based on the type of organic material you used. For extract from commercial granulated organic fertilizer mix 3 cups of extract to 15 cups of fresh water. For grass clippings mix 1/2 gallon of extract to 1/2 gallon of fresh water, and for stinging nettle, dilute 1 cup of extract to 10 cups of water. Compost extract does not need to be diluted. Use the solution no more than once per week on vegetables and ornamental plants.