Acid-loving plants are those that prefer a soil pH below 7. The pH, or potential hydrogen ions, in soil can range from 0 to 14. Seven is considered neutral, and anything below 7 is acidic. Soils with a pH over 7 are alkaline.
There are many things that increase the acidity of soil, such as:
- Frequent rainfall: Water leeches calcium and magnesium from the soil when it passes through.
- Acid rain: Areas with high levels of pollution may have acidic soil from the acidity of the rain.
- Fertilizers with ammonium or urea: These chemicals contribute to a more acidic soil.
If you have naturally acidic soil, acid-loving shrubs, flowers, trees, fruits, and vegetables will thrive in your garden. For these plants, a pH of around 5.5 is ideal, though some prefer even more acidity.
Acid-loving flowers will add color and texture to your decorative garden beds. These flowers typically enjoy soils with a pH of around 5.5. Most don’t enjoy alkaline soils.Â
Hydrangeas are a unique exception. Hydrangea flowers react to soil acidity in a vibrant way by changing their color based on the pH level. When hydrangeas are planted in acidic soil, the flowers are blue or lavender-blue. In an alkaline soil, the flowers become pink or red. Neutral soil produces purple hydrangeas.
Some examples of flowers that thrive in acidic soils include:
- Camellias: zones 6 to 10
- Japanese Iris: zones 4 to 9
- Hydrangeas: zones 3 to 9
- Trillium: zones 4 to 9
- Daffodils: zones 3 to 8
- Heathers: zones 4 to 8
- Nasturtium: zones 9 to 11
- Marigolds: zones 2 to 11
- Irises: zones 3 to 10 in the West and 3 to 8 in the East
- Blue Ageratum:Â zones 10 and above
Acid-loving trees can thrive with minimal assistance in acidic soils. You can encourage a deep green color in these evergreens by fertilizing them in the spring and fall. These trees love acidic soil:
- Magnolia: zones 7 to 9
- Dogwood: zones 3 to 8
- American Beech: zones 4 to 9
- Pin Oak: zones 4 to 8
- Willow Oak: zones 5 to 9
- Colorado Blue Spruce: zones 3 to 7
Acid-loving shrubs are sensitive to any increase in soil acidity. You can help keep the pH low by mulching around them with peat moss or pine needles.
- Fothergillas: zones 4 to 8
- Holly: zones 5 to 8
- Gardenia: zones 8 to 11
- Azaleas: zones 5 to 8
- Rhododendrons: zones 5 to 8
- Bleeding Heart: zones 3 to 9
- Heath: zones 5 to 8
- Bottlebrush Shrubs: zones 5 to 8
Acid-Loving Fruits and Vegetables
If you’re starting a fruit or vegetable garden in acidic soil, it’s important to select the right plants so you’ll get a fruitful harvest. Select American varieties over European varieties when available for the best results. These plants typically prefer full sun. Acid-loving produce options include:
- Radishes: zones 2 to 10
- Sweet Potatoes: zones 9 to 12
- Peppers: typically zones 7 to 11, depending on type
- Rhubarb: up to zone 6
- Blueberries: zones 3 to 7 depending on type
- Cranberries: zones 2 to 6
- Currants: zones 3 to 8
- Elderberries: zones 3 to 8
- Gooseberries: zones 3 to 8
- Broccoli: zones 3 to 10
- Cabbage: zones 1 to 9
- Cucumbers: zones 4 to 12
- Sweet Corn: zones 4 to 8
- Tomatoes: zones 5 to 8
Acid-loving herbs usually like a soil pH between 6.0 and 7.5. Some, like parsley and rosemary, can handle a pH as low as 5. Try these herbs for an acidic garden:
- Parsley: zones 4 to 9
- Basil: zones 10 and above
- Oregano: zones 5 to 10
- Sage: zones 5 to 8 as a perennial, zone 9 and above as an annual
- Thyme: zones 2 to 10
How to Care for Acid-Loving Plants
If your soil is naturally acidic, acid-loving plants should do well with only routine soil maintenance. However, if you’re altering the pH of your soil to accommodate these plants, you’ll need to test your pH levels regularly and make sure you’re keeping it below 7. A good soil testing laboratory can provide custom recommendations for how to adjust your soil’s pH if it’s higher than you’d like. Elemental sulfur and ammonium sulfate are common additives that will help lower your soil’s pH.
Plants that prefer acidic soil will develop iron chlorosis if the soil is too alkaline. This causes yellowing of young leaves in between the leaf veins. The leaf veins themselves will stay green. Don’t confuse this with a magnesium deficiency, which will cause the older leaves to yellow first. A nitrogen deficiency also causes yellow leaves, but this issue is distinguishable by the presence of weak stems as well.Â
Most acid-loving plants prefer well-drained soil. Compost is a great amendment that will provide extra nutrients for your garden. Use a fertilizer that’s designed for acid-loving plants with a formula around 10-5-4 unless you’re dealing with a specific nutrient deficiency.
If some of the acid-loving plants on this list intrigued you, but your garden is naturally neutral or alkaline, you can still use these options in your garden by amending the soil and taking care to regularly adjust the pH level. Whether you have naturally acidic soil or you choose to create it yourself, you’ll find that these acid-loving plants will love a low pH and offer outstanding growth in these conditions.