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Get to know your soil's pH level and what grows best in it

despite our mother's repeated exhortations to not judge a book by its cover, we are guilty, guilty, guilty when it comes to houses.

We totally use the tiny photo that accompanies each listing to decide whether to call or click for more details.

And that right there shows the power of curb appeal and why you, as a homeowner, should cultivate a green thumb, or at least some semblance of one.

Your first, and probably most important, assignment: Get to know your soil and what will grow best in it.

You'll need to remember some basic chemistry, as the pH level of your soil has a lot to do with creating a lush landscape. If the pH level is not suitable, a plant may absorb too little of the nutrients it needs to survive, leading to malnutrition. Or it might absorb too much, leading to toxicity. You may choose the right place for a particular plant in terms of sunlight and water, and even give it the proper fertilizer, but if the soil pH is off, that plant still may appear starved or poisoned.

Soils are described as acidic (pH levels of 0 to 7.0) or alkaline (levels of 7.0 or higher). The median for Florida soils is 6.1, or slightly acidic, although coastal areas or areas exposed to a lot of construction materials such as concrete or stucco often are more alkaline.

Some plants thrive in acidic soil (azalea, ixora, gardenia), some prefer alkaline (butterfly bush, yucca, elm), and many can tolerate a wide range of pH levels (croton, bamboo, banana, oleander). You can add some nutrients to your yard to target your soil pH for certain plants, but there's a lot to be said for choosing plants that suit your soil. Here's how to go about getting your soil tested and what to do once you get the results.

Take the test

You can do soil testing yourself using kits available at garden centers and big-box stores. Just be aware that some of the recommendations are based on soil types from other parts of the country and not on Florida's unique sandy soils. A safer bet is to go through your county extension office. Some local offices offer soil testing; others offer forms and contacts for the University of Florida in Gainesville. The UF lab offers a pH and lime requirement test (Test A) for $3 and a more in-depth test that covers pH and lime requirements as well as potassium, phosphorus, calcium and magnesium levels (Test B) for $7. For more on UF soil testing, go to To find your local extension office, go to Know that it may take a couple of weeks to get test results, and your soil will need some time to adjust to added nutrients, so do your tests well in advance of your planting time.

How to take a soil sample

Specific guidelines may vary depending on which test you decide to use, but in general, here are the steps for preparing a soil sample.

• Decide which areas of your yard you would like to sample. Samples from vegetable gardens, turf areas and flower beds should be sent in separately.

• Use a trowel to dig out a V-shaped wedge. For turf areas, dig down about 2 to 4 inches; for areas of vegetables and landscape plants, dig down about 6 to 8 inches.

• Walk in a zigzag pattern and stop occasionally to remove soil for a sample. You should take 10 to 15 samples.

• Put all the soil you collect into a plastic bucket and mix it well. Remove any rocks or plant debris.

• Spread the soil out on a newspaper to dry.

• Pack about 2 cups of the soil in a resealable plastic bag to send to the lab.

Acidic soil

Most Florida soils are slightly acidic. You can temper the acidity of the soil by adding standard lime, which reacts with water and releases calcium that neutralizes acid and raises the pH level. For lime to work, it needs to be well mixed into the soil. This is easy to do before you plant but can damage the roots of existing plants. For existing beds, apply lime to the surface and water it in. Dolomitic lime is another popular option; in addition to calcium, it adds magnesium, a nutrient often lacking in Florida soil.

Alkaline soil

It's much harder to adjust alkaline soils, and fixes are temporary at best. You can add elemental sulfur to highly alkaline soils; bacteria in the soil change the sulfur into sulfuric acid, which neutralizes the soil alkalinity. The effects are localized, however, and once the sulfur supply is exhausted, the pH levels will again rise. More sulfur, of course, can be added, but adding too much too frequently can hurt or kill your plants (never add more than 5 to 10 pounds of sulfur per 1,000 square feet per application). According to the University of Florida Extension Service, some materials containing sulfate (iron sulfate, aluminum sulfate) and peat or manure also can help adjust alkaline levels, but these materials decompose with time so more applications will be necessary.

Choose the right plants

Most landscape plants and turfgrasses can grow in a wide range of pH levels, and if your soil tests within a range of 5.5 to 7.0, you don't need to make adjustments. You can find the ranges for plants on the Extension's Florida Friendly Plant List, offered online at list.pdf, or at local extension offices. Below are some plant suggestions for each soil type.

Soil pH below 5.5 (acidic): Bahia grass, centipede grass, azalea, blueberry, American holly, blue hydrangea, ixora, phlox

Soil pH above 6.0 (alkaline): St. Augustine grass, Zoysia grass, butterfly bush, elm, pink hydrangea, ash, sycamore, yucca

Tolerant of various pH levels: Bermuda grass, bamboo, English ivy, banana, oleander, crape myrtle, croton, hawthorn, honeysuckle

Get to know your soil's pH level and what grows best in it 01/01/10 [Last modified: Friday, January 1, 2010 3:30am]
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