The bonfires on the levee have just quit smoldering, which means it must be time to plan for the new year.

Weather has been predictably cold and wet lately with an occasional 70-degree day thrown in for good measure. So in Louisiana, you can continue to plant cool-season vegetables and bedding plants in January.

And late this month is a good time to start transplants from seed if you plan to grow tomatoes, eggplants and other warm season crops in mid-March. But many plants are dormant (or dead) right now, and this is a good time to evaluate your landscapes and gardens.

Spring planting and blooming time will be upon us soon, and it’s best to be prepared. You’ll be well-prepared if you get a soil sample of your bed, garden or yard analyzed. A soil test will tell you your soil type, pH, and the levels of many important plant nutrients.

The results will guide you in your pre-planting preparation work, as well as what to do during the growing season.

By knowing what is and isn’t in your soil, you can better decide what nutrients to add to the soil and which you don’t need.

Gardeners often only add fertilizer in the form of nitrogen, phosphorous and potassium (NPK). These are the three nutrients needed in the greatest quantities.

They are represented by the three numbers, in that order by percentage, on the fertilizer bag. Examples include 13-13-13 or 8-24-24.

But your plants may also need additional micronutrients like calcium, magnesium, etc. for best growth if the soil does not provide enough. On the other hand, if you add minerals that are already present in high levels in the soil, they can cause toxicity problems and runoff pollution.

At the very least, you’ve wasted money and effort on something you didn’t need.

To take a soil sample, dig to the depth where you expect the majority of plant roots to grow. This is about 4-6” for most vegetables or small ornamentals, 2-3” for grass, and 10-15” for large trees.

Take multiple samples from random locations in the growing area. In a rough square, dig at least one sample from each corner and one from the center. Then mix them together in a bucket and use a pint of this mixture as your sample.

Soil test kits are widely available and pretty cheap. They’ll get you an approximate view of soil chemistry, but more accurate results can be obtained from a laboratory.

Samples may be sent to the LSU Soil Testing Lab in pre-paid postal boxes available at LSU Ag Center offices and some area nurseries and hardware stores. The cost is $10/sample, plus $6 shipping for up to three samples. When your results come in, you may contact me to help you interpret them. Lab results can be confusing if you’re not used to reading them.

On large areas, one sample per acre is recommended. One sample for a garden or yard will also usually suffice.

But if you suspect different soil types because of location, flooding, past fertilization history, or other reasons, bring in separate samples from the different areas. Unless dramatic changes occur, a given area only needs to be sampled about once every three years.

If you want to know more about gardening, landscaping, or anything else horticultural, contact the St. John, St. James, & St. Charles Parishes County Agent André Brock at abrock@agcenter.lsu.edu. Also, the LSU Ag Center’s website can be accessed at lsuagcenter.com with lots of user-friendly information, including this article.