Do I have to get a soil test report or can you just tell me how much fertilizer to add?
A soil test is the only accurate way to determine how much fertilizer each yard needs. A soil test chemically extracts nutrients from the soil and measures their “plant-available content” in the sample. The quantity of nutrients extracted determines the type and amount of fertilizer to recommend. The soil sample's pH and acidity are also measured to determine whether lime is needed and how much. The NCDA&CS provides soil testing. A small fee applies to each soil sample submitted to the NCDA&CS from December through March, the peak season for soil testing in North Carolina. No fee is required for soil samples submitted to the NCDA&CS during the rest of the year (April through November). Samples must be mailed in to the NCDA&CS, and boxes are available at their main office, 4300 Reedy Creek Road, Raleigh, NC, or at any N.C. Cooperative Extension center. More information and forms are available on the NCDA&CS website.
How often should soil be tested?
If a soil test report shows pH and nutrient levels within the range needed to grow plants, you may not need to sample every year. As a general rule, test sandy-textured soils every two to three years and clay soils every three to four years. However, if nutrient or pH levels are excessively high or low, submit a sample every year to determine how much improvement you've achieved and what additional amendments you should make. In addition, if problems occur during the growing season, collect a sample and have it analyzed.
Can I add Epsom salts to my plants?
Epsom salt (magnesium sulfate) can sometimes be beneficial, especially in sandy soils that may be low in sulfur or magnesium. However, the best approach is to rely on a soil test and adjust soil pH and nutrient content based on the soil test report’s lime and fertilizer recommendations.
Why are my (azalea, blueberries, maple, rhododendron) leaves yellow?
If water isn't the issue, the likely culprit is pH. Azaleas, blueberries, maples, and rhododendrons are acid-loving plants requiring a pH of 4.5–6.0 to thrive. Knowing your soil pH will help you select plants that will thrive in your soil. Altering soil pH is difficult, but you can do it in small areas.
My shrubs/trees are wilting; the leaves are brown on the edges and are falling off. What is causing this?
This could be salt injury from improper fertilizer application. High salts reduce a plant's ability to take up water from the soil, and salts can move through the plant's vascular system to the leaves, where water evaporates and concentrates the salt to toxic levels. Plants may recover from salt/fertilizer injury if you reduce high salt levels through repeated, deep irrigation. The best defense is to get a soil test and follow the fertilizer recommendations. Avoid the use of high salt fertilizers such as sodium nitrate; use slow-release fertilizers and apply as recommended. Azaleas and blueberries are very susceptible to salt/fertilizer injury.
My soil is very heavy clay. What can I do?
- There are several ways to manage clay soil.
- The easiest thing you can do is select plants that perform well in clay soil. Water moves slowly into clay soil, so irrigate slowly. A soaker hose is a good option.
- Clay soil compacts easily when wet, so keep foot traffic and vehicles off your garden beds.
- Another option is to add organic matter like compost or pine bark to the soil. Also add a few inches of organic matter on top every few years.
- Build a raised bed on top of the clay soil and bring in soil from a reputable source. Loosen the clay layer in the existing soil before adding new soil to the raised bed so water can adequately drain.
My lawn soil is compacted; what can I do to fix it?
Foot traffic, mowing, recent home construction, and even rainfall can contribute to soil compaction, which can be especially problematic in clay soils. Turf grass roots need air and water to grow. Core aeration removes small cores from the top few inches of soil, allowing air, water, and nutrients to reach your turf's root zone. The result is reduced water runoff and improved water and nutrient uptake, gas exchange, thatch breakdown, and heat and drought tolerance.
The best time to perform core aeration is when grass is actively growing. That means late spring or early summer for warm-season grasses and fall for cool-season grasses. The soil should be moist, but not wet. Mark sprinkler heads, shallow lines from the sprinkler, and underground utility, cable, and septic lines to prevent damage. Leave soil cores on the lawn; they will work their way back into the soil within two to four weeks. Lawns may be fertilized, seeded, or top dressed with a soil amendment immediately after coring, although ensure the timing of fertilization corresponds with the recommendations on the maintenance calendar for your turf. Aerate lawns once a year, especially under heavy use and in heavy clay soils. Spike aeration is not recommended, as it only further compacts the soil.
