Plants In Your Home And Garden That Don't Like Potato Water As A Fertilizer

You may already be familiar with the gardening hack that encourages watering your plants with potato water. The theory behind it is simple: when potatoes are boiled, some of their water-soluble nutrients leach into the surrounding water, such as potassium, phosphorus, and magnesium. Once this water has cooled down, using it on your plants gives them a boost of nutrients, and its starchiness can kickstart the growth of beneficial microorganisms in the soil and aid plants' carbon metabolism.

However, that doesn't mean you can take your leftover potato water and dump it on just any plant. There are important precautions to take when preparing the water, and while properly made potato water likely won't harm your plants, it doesn't benefit them all equally. The shorter a plant's root system is, the more likely it is to become waterlogged, which can lead to oxygen deficiency and damage to its roots. To avoid this, it may be best to skip the potato water for shallow-rooted plants with lower moisture needs, including cacti, succulents, English lavender, and most drought-tolerant ground cover plants. 

Even if you're using potato water on plants that love water from boiled vegetables, some precautions apply across the board. Before you pour that potato water, consider how established your plant is. Potatoes are potassium-rich, and while the potassium in potato water is a helpful nutrient for plant growth, too much of it can cause a nitrogen deficiency and inhibit root development. Because of this, it's not recommended to use potato water on new seedlings or transplants, at least not without diluting it with at least 50% regular water.

You can't just use any old potato water, either. If there's salt in the water, don't use it since too much salt in the soil can decrease how much water is available to your plants and cause stress. Also, be sure to fully strain the water since potato piece leftovers can start to grow mold and attract pests. The cooled, strained, and unsalted water can be stored in your refrigerator for up to a week. It shouldn't replace your other forms of watering, and you'll still need to flush your plants with regular water to prevent starch buildup in the soil. If you use potato water too often, you risk oversaturating the soil and damaging your plant. Stick to using it once a week at most and even less frequently for plants that are sensitive to fungal issues and prone to becoming waterlogged, such as jade and African violets. If you want to introduce potato water to these plants more carefully, give bottom watering your houseplants a try.