10 Plants for Gardens With Acidic Soil

Blueberries like 'Perpetua' love acidic soil. A soil test kit, available online or from a hardware store or garden center, makes it easy to determine whether your soil is acidic or alkaline.

Start by taking dry soil samples from different areas in your planting site. Mix them with the chemical solution in the test tubes from the kit, and mark the tubes so you’ll know where each sample came from. (The pH may not be the same throughout your site.) Now compare the solution colors to the chart in the kit. Dark green indicates alkaline soil (the pH is above 7), while yellow or orange means the sample is acidic (the pH is below 7). Bright green means neutral soil, or a pH of 7.0. To increase your soil’s acidity, use sphagnum peat around your blueberries or apply a high-acid fertilizer.

Medium to very acidic soils are fine for rhododendrons. Like azaleas, these shrubs can tolerate a pH of 4.5 to 5.5 or 6.0, and they flourish in woodland gardens, forested areas or beds where leaves and other organic materials have decayed. 'Dandy Man Pink' blooms in spring and is hardy in USDA zones 5-9. Give your "rhodies" a fertilizer labeled for rhododendrons and follow the directions on the package. Be careful not to feed too heavily or too often; excess fertilizer can damage and even kill your plant.

When you take a walk through the Eastern woods in early spring, watch for colorful Trillium erectus popping up through the leaf litter. This native wildflower, also known as wakerobin, thrives in shady, acidic sites where the soil is moist and contains plenty of organic matter. Resist the urge to dig up these pretty plants; leave them in nature, and purchase from a commercial source instead.

Most ferns thrive in slightly acidic soil, although this frilly Christmas fern is adaptable enough to grow in a slightly alkaline site. It's a good idea to re-test your soil periodically, so you can monitor any changes in the pH and add more amendments as needed. Soil gradually becomes more acidic over time, as rainfall leaches away its calcium content and organic matter decomposes. Applying fertilizer also slowly increases soil acidity.