Get Your Soil Tested During The Dormant Season

December 15, 2009 by ·

One of the most important needs of plants is good soil for them to grow in. A soil test from the University of Georgia is the most accurate and effective way to assess the nutrient status and the relative acidity of the soil (pH). Applying fertilizer without a test can lead to applying too much or too little lime and fertilizer needed for optimum plant growth.

To collect the soil, take a minimum of ten samples randomly in the area that requires testing and mix the soil thoroughly in a container, like a bucket. Bring two cups of the soil to the Extension office for testing. You will then place the soil in a small bag, and fill out some information on the side of it. For a fee of $8.00 per sample, the Extension office will mail it to the University of Georgia Soil Testing Laboratory with the results being sent to you in seven to ten days.

Soil tests measure the level of several nutrients of importance to plants: phosphorous, potassium, calcium, magnesium, zinc, manganese, and pH. The information on the nutrient levels, the pH, along with the crop to be grown, is used to determine the necessary nutrient requirements. Nitrogen is not routinely a part of the normal soil-testing regimen since nitrogen is quite mobile in the soil and may be leached out before planting. Recommendations given are based on the amount of nitrogen required for the plant growth in a year.

Here are a few basics of soil chemistry for interpreting the test results: The measurement of the acidity of a soil (the pH) is one of the most important factors in determining a soil’s relative fertility. The pH scale ranges from 1 to 14 with 1 being the most acidic, 14 being the most  alkaline, and 7 being neutral. Soils with low pH, that is, acidic soils, restrict the availability of many nutrients that are needed in large quantities. It also increases the availability of others nutrients needed in very low quantities leading to toxicities. The preferred pH for our soils in Georgia is  6.0-6.5; however, the average pH is 4.8, which is acidic. The addition of calcium in the form of lime is the preferred way of increasing the pH of the soil. Since changes in the pH take time, applications of lime are best done months ahead of planting. In some cases the soil is too alkaline, above the pH of 7. Adding acidic soil amendments, like pine bark or peat moss, to the soil is one way to reduce the pH. Sulfur and ammonium sulfate can be used, but do so with extreme caution since they can cause harm to plants. Different plants have differing soil pH and nutrient requirements. Most plants grow at a pH between 6.0 and 6.5; however, some plants prefer a more acidic soil since they have higher iron  requirements, such as blueberries, azaleas, rhododendrons, and mountain laurels. They need a soil pH of 4.0 to 5.5.

The soil test report shows available soil nutrients and pH, and recommendations for improving pH and nutrient levels. Lime recommendations are given in pounds per square feet and are self-explanatory. Nutrient recommendations are also given in pounds (lbs) per square feet.

The three numbers on fertilizer bags represent nitrogen (N), phosphorous (P), and potassium (K) respectively and denote the percentages in the bag of each particular nutrient. For instance 10-10-10, the most common fertilizer has 10% nitrogen, 10% phosphorous, and 10% potassium. In other words, it is in a 1:1:1 ratio. The other 70% of the bag is inert ingredients that are used to carry the three nutrients. A forty-pound bag of 10-10-10 has 4 pounds of N, P, and K respectively since 10% of 40 is 4. So, if the soil test report recommends 60 pounds each nitrogen, phosphorous, and potassium per acre, one may use 10-10-10, 20-20-20, or any other fertilizer that has a ratio of 1:1:1. If you use 10-10-10, you would need 600 pounds of fertilizer (60 x 10). Divide the 600 pounds of fertilizer by the number of pounds in the bag to find out how many bags of fertilizer you would need.

Soil test results and fertilizer recommendations can make sense if you take the time to analyze them. Sometimes, however a homeowner or a business will have peculiar situation or set of circumstances and will need help wading through the numbers. This is where County Extension agents and personnel can come into the picture and provide help. Feel free to call your local office anytime.

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Scented Geraniums: A Worthy Addition To The Home Garden

February 15, 2009 by ·

Scented geraniums (Pelargonium species) are excellent herbs to grow in the garden. They are tender perennials and are planted in containers so that they can be easily brought in for the winter. These plants are treated as annuals, but have been known to survive the winter if mulched and the temperatures do not get too cold. They are grown for their scented leaves, not for their flowers like traditional geraniums. Scented geraniums come in all shapes, sizes, and colors. Some have highly aromatic foliage. Some varieties have bright red flowers, while others vary from white to pink. Their leaves range from rounded to finely cut. The leaves can be dried and used in potpourris or added to teas.

They should be grown in well-drained soil and in full sun. However, during the hot part of the day, they need some shade to keep from being scorched. The smaller leafed varieties have a tendency to become “leggy.” Consistent pruning will encourage a more dense growth. It is best to pinch them back with your fingers to remove the stem tips above a leaf. Leave several leaves on the stalk because the plants will branch out from here.  They are light feeders and only occasionally need a dose of all-purpose fertilizer like 10-10-10.

Cuttings can be rooted in a glass of water but do better when rooted in a soil-less growing media like sand or vermiculite. Take six-inch cuttings, strip of the lower leaves, and dip into rooting hormone. Keep the rooting medium damp. After a few weeks, gently tug on the plants. If there is resistance, then they have formed roots and can be transplanted to a growing medium.

There are a multitude of scented geraniums available. They are categorized by aroma, such as rose, mint, fruit, spice, and other pungent fragrances. The scented geranium can smell like rose or lemon, or the plant may give off a scent of cloves or nutmeg. It may have the odor of pine or peppermint; apple or apricot; or chocolate or coconut. One of the most commonly grown cultivars is ‘Attar of Roses.’ Rubbing the leaves together of this old-fashioned scented geranium will reward with the fragrance of roses.

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Azaleas For The Southern Garden

February 14, 2008 by ·

There are over 900 species of azaleas (Rhododendron spp.) and over 8000 recognized hybrids. Azaleas belong to the Ericaceae family (the heath family which includes blueberries and mountain laurels) and are used extensively by gardeners. These plants freely hybridize and there are new cultivars introduced every year. Gardeners should seek out the new cultivars to add excitement to the spring garden.

The azalea is found all over the world but most notable horticultural species are indigenous to Japan, China, and the United States. In the US, native azaleas are found in the Pacific Northwest and the Southeastern US. Most azaleas grown by home gardeners are the Asian evergreen varieties, although the native deciduous Piedmont Azalea is still prized by many. The plant’s beautiful blooms and stout character has earned it a place in most American gardens. The azalea is a favorite of gardeners and is grown by the millions in southeastern nurseries.

The azalea is a tough plant when properly planted in an adequate site. Azaleas prefer cool, partially shaded sites. Although some varieties tolerate sun better than others, they all prefer an area that is not exposed to long periods of hot full sun and drying winds. Flowers last longer when plants  are partially shaded. Azaleas exposed to full sun are more susceptible to lace bugs.

Proper cultural practices are the first line of defense against insects and diseases. Cultural factors to consider when choosing a site for an azalea include the soil type and drainage (azaleas require good drainage), the amount of sun (azaleas are primarily a shade species), pH of soil (azaleas require low/acid pH), and temperature (azaleas are killed by frost in zones lower than 5). Iron is essential for healthy azaleas. Iron is available for uptake by azaleas when the soil pH is low (acidic). When soil pH is too high (alkaline), iron becomes unavailable and chlorosis, or yellowing of the youngest leaves, may occur. A sign of iron chlorosis is the area between the veins turning yellow or light green, and the veins are darker green.  Application of iron as a foliage spray will usually give quick, temporary results when applied during the growing season.

Poor drainage is the main cultural factor that predisposes azaleas to attacks by pests. Azaleas are shallow rooted, have very fine roots, and will  wilt rapidly. They must be kept adequately irrigated at all times to prevent stress. Plant azaleas in shallow holes with several inches of the root ball above the soil surface and mulch deeply with decomposed mulch. Prune in the spring after flowering. Pruning after July will remove the blooms that have been set for the following year. Fertilize with an “acid loving” plant fertilizer and water as needed. When planted and maintained correctly, the azalea will resist pests and bring beauty to the garden like few other plants can.

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