How to Use Whey for Watering Plants

Whey is a by-product of the cheese-making process.

Many people who make cheese at home wonder what to do with whey, a byproduct of the process. Some choose to pour it down the drain, while others use it in bread making, but it also makes a good plant fertilizer. Whey is acidic, with a pH between 4.0 and 6.1, so it is a good amendment for soils that are too alkaline. Whey provides phosphorus and potassium, and contains simple organic compounds, making it easy for plants to take in. Use whey to fertilize houseplants as well as for fertilizing larger outdoor vegetable gardens, trees and shrubs.

Things You'll Need

• Large watering can
• 1 cup measuring glass
• 9 cups water
• Bucket
• Yardstick

Instructions

1. Remove the whey from your refrigerator. To avoid any unwanted odors, strain the whey well before using it on indoor plants. Whey used outdoors does not have to be strained.

2. Measure 1 cup of whey into the watering can. Add 9 cups of water and mix well. Use to water houseplants by alternating watering one week with the whey mixture and one week with regular water. If any plants do not seem to be responding well, discontinue the use.

3. Put the yardstick into the bucket and pour the whey into the bucket until the level is at 1 inch. Pour water from the garden hose in until it reaches 10 inches. Using the 1 cup measure, pour 1 cup of the whey solution around the base of small vegetable plants once a week. Fertilize larger plants and trees by applying half a bucket at a time to the base of the trunk and then watering as usual.

4. Fertilize acid loving plants, like junipers or roses, with a more concentrated solution by mixing 1 part water to 1 part whey.

Tips & Warnings

• Freeze whey in ice trays and then add one whey cube to each houseplant.

• Keep whey refrigerated or frozen until use.

• Add any unused whey to your compost heap.

• Whey is too acidic for plants that prefer alkaline soil, such as azaleas.

• Whey made with vinegar will be even more acidic.

• Do not apply whey to gardens before seeds have sprouted. Doing so may deter germination.

References

• Restoration and Reclamation Review: Soil degradation and the use of agricultural and organic industrial by products as soil amendments
• Agricultural and Applied Economics: Uses of Whey in Farmsteading