St. Tammany Horticulture Update: April, May, and June 2020

As the state continues to manage the COVID-19 outbreak, we are all told to hunker down at home and practice social distancing techniques while out shopping for essential items. Many of us are working from home along with our children and spouses. Break up the monotony inside and look for outdoor activities to spend time with the family. Activities like gardening, planting annual color, growing fruits, herbs, and vegetables, making mixed container plantings, and more. The ideas are endless. Use this newsletter as a starting point to better understand the outside world and the things you can be do to improve it.


The beginning of this period (April) is a transitional time for annual color and bedding plant beds. Plants such as dianthus, pansies, violas, snapdragons, and petunias are in full flower production mode. These and other cool season flowers are in their peak. Focus efforts on maintaining these plants by dead-heading, weeding, and culling diseased plants. As plants are removed, replace with mulch until the entire planting is ready to be redone.

Choose warm season flowers to plant now and enjoy during the summer months. You can start seeding flower seeds of amaranthus, balsam, celosia, cleome, cosmos, gomphrena, marigold, portulaca, purslane, sunflower, and zinnia. Create a supportive seed bed to ensure consistent germination. Remove any weeds, add an inch layer of organic material (composted manures, homemade compost, etc.), add fertilizer (organic or conventional) and cultivate the soil. Using a garden rake, smooth out the top, create a flat surface, and lightly pack. The bed is now ready to sow seeds. Seeding depth is generally related to the size of the seed. Aim to plant seeds twice as deep as they are wide.

Garden centers and nurseries are fully stocked with their spring inventories. Try not to become overwhelmed with all of the choices. Notate their sun, water, and soil requirements when comparing different plant species. Transplants are plentiful. Look for small plants of begonia, melampodium, salvia, torenia, pentas, and vinca to plant into the flower garden.


Prune azaleas and other spring blooming shrubs soon after they finish flowering. Timing of pruning is crucial because these plants start setting the flower buds for next year during the summer months. Remove up to one third of the plant at pruning. Make an application fertilizer after pruning. Use the results of a soil test to select a fertilizer that supplies what nutrients are deficient in the soil. If no soil test is available use a general slow release fertilizer with values for N, P, and K, for example, 12-6-12 or 12-6-6.

Gardenias are in full bloom this time of year and you can easily tell by the fragrance in the air. One of the reasons why gardenias are so popular in the landscape is because there seems to be a variety for almost any space in the garden. The lowest growing selection is ‘Dwarf Gardenia’. It has a spreading-like growth habit that reaches 2-3ft tall and 3-4ft wide. The cultivar ‘Daisy” is slightly taller at 2-4ft tall and wide. ‘Frostproof’ gardenia is a medium sized shrub with a more upright growth habit. It can reach 4-5ft tall and 3-4ft wide. ‘Frostproof’ gardenia is a Louisiana Super Plant, an award given to plants that perform well in all parts of Louisiana. ‘August Beauty’ is one of the larger growing cultivars in the trade. This is what many of our grandparents grew as gardenia. It can grow 6-8ft tall and 5-6ft wide. All of the cultivars discussed in this section produce the typical white flower and sweet fragrance.


Now is the spring vegetable season. Focus on planting, growing, and producing warm season vegetable crops this time of year. Warm season vegetable crops to plant this season include bush beans, pole beans, cucumbers, eggplants, melons, peas, bell peppers, hot peppers, pumpkins, squashes, sweet corn, sweet potato, and tomatoes.

Tomatoes are some of the most popular vegetable garden plants in the world and are grown in every Louisiana garden. The secret to producing a good crop of tomatoes is to maintain healthy bushes.

Two cultural methods used to achieve this are pruning and staking. Pruning tomatoes is the practice of removing suckers. Suckers are sprouts arising from the main stem and a branch. They typically grow at a 45° angle. Remove the first two suckers from each bush.

Staking is an important technique to support excess weight of ripening fruit. Tomato cages are very common and can be installed at planting so that the young tomato plant is allowed to grow into it. A simple wooden stake with several support ties is a tried and true method that works well. For a long row of tomatoes, the Florida weave technique can be helpful. Two T-posts are erected at the end of each row, with wooden or rebar stakes (5-6ft long) are erected every 3-4ft down the row. Tying string to the front T-post 10-12 inches from ground level, loop each support as you go down the row, keeping the string taught. Loop around the back T post and continue the process as you make your way back up the other side. Make sure the tomato plants are sandwiched between the string layers. Continue the process as the plants grow taller.


Side view of the Florida weave trellising technique.


Top down view of the Florida weave trellising technique.


Cultural practices are the weapon of choice when it comes to maintaining a healthy, weed free lawn throughout the growing season. Mowing lawn grass correctly is one of those practices. The one third rule states that you should mow the grass often enough so that you remove one third of the grass plant with each mowing event. Mowing when the grass is too high leaves behind clumps of clipping that interfere with photosynthesis and take away from the lawn’s appearance.

Proper mowing height is another factor to consider. Each species of turfgrass prefers to be mowed at a specific height. Cutting too low damages the crown of the plant whereas as cutting to high takes away from its clean cut appearance.

Hold back fertilizer until Tax Day (April 15). The best fertilizer for your lawn is one that supplies nutrients that are deficient in your soil. The only way to know what nutrients are deficient in your soil is to submit a soil sample through your local extension office. The key pieces of information to look for on the analysis report are soil pH and nitrogen, phosphorous, and potassium (N-P-K) concentrations. An AgCenter Extension Agent can help gardeners understand their soil reports and recommendations.

10/7/2020 5:07:26 PM
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