Using Aluminum Sulfate for Gardening

The ph levels of soil can present problems for gardeners since many plants require a low ph level to thrive. The effects of soil ph can be clearly seen in hydrangeas. The color of the flowers is an indicator of the acidity of the soil feeding it. Blue hydrangeas turn pink if the soil is too alkaline. Adding aluminum sulfate to the soil will turn the blooms blue.

Testing Soil ph Levels

For gardeners who have their soil tested, a 7 ph is considered neutral while anything over 7 is alkaline and under that is acid. Test kits for ph are available at local hardware and gardening stores, and are easy to perform. Getting the right ph levels in the soil helps plants to absorb nutrients and thrive. There are chemicals that can be added to soil to create the right ph for the flowers, fruits and vegetables in a garden.

Correcting ph Levels

If acid levels in soil are too high, many gardeners use lime to increase the ph level. However, in areas where soil is very alkaline, plants may not thrive at all. Aluminum sulfate reacts with water to create a mild sulfuric acid solution which can help lower ph levels and give plants the nutrients they need. Aluminum sulfate can be purchased at gardening centers and even some drug stores. Sprinkling it evenly over the soil and then watering will release the sulfuric acid and lower the soil ph.

Acid Loving Plants

It is no surprise that grapes grow well on the slopes of volcanic mountains since this is an area where aluminum sulfate occurs naturally. Grapes prefer a fairly acid soil as do strawberries, blueberries and raspberries. Additionally, ornamental bushes like azaleas usually grow best in soil with a low ph as do many vegetables including cauliflower, corn, cucumber, garlic, sweet potato, rhubarb and water cress. Most other vegetables and fruits prefer a neutral ph rather than high alkaline levels.

Aluminum Sulfate in Gardening

Aluminum sulfate is not a fertilizer, but it balances soil ph which allows plants to absorb more nutrients from soil. It may be present in special gardening soils, so if using a gardening soil, check the ph before adding aluminum sulfate. The chemical compound can also neutralize phosphates in both soil and water which can be important if waste water is being used in the garden. Soaps and detergents add phosphates to water so the use of waste water may change the soil ph.

Handling Aluminum Sulfate

Aluminum sulfate is available as a powder or a liquid, and special precautions should be taken when handling it. Because this chemical can cause skin irritation, skin should be covered and gardening gloves worn. A mask or respirator should also be used if the gardener has chosen to use the powder form. If the chemical gets in eyes or on skin, flush immediately with cold water. In case of accidental ingestion, contact a hospital without delay.

Aluminum sulfate in gardening is not a new idea and many avid gardeners have been using it for years to improve the yield of their gardens. For those whose gardens are not thriving, a ph test may confirm the need to lower the ph of the soil in order to help plants grow strong and healthy.