(News article for October 9, 2019)

This is kind of a big deal for me – my first newspaper article for my home parish. As Henry Harrison mentioned would be the case when he wrote his last column, I have assumed LSU AgCenter horticulture responsibilities for Washington Parish.

I grew up in Bogalusa. After finishing my master’s degree in horticulture at North Carolina State University, I stayed in NC and worked as an extension agent (with horticulture responsibilities, primarily) with NC Cooperative Extension for five and a half years. I returned to Louisiana in 2012 and went back to school at LSU to work on my Ph.D. in plant pathology.

I have been working for the AgCenter since I finished my degree in 2016. I worked on campus in the Plant Diagnostic Center for a little over a year and have been an extension agent since February 2018. I initially worked in Livingston and Tangipahoa Parishes but, following Mr. Harrison’s retirement, switched to Tangipahoa and Washington Parishes.

I want to thank Henry for his support over the years. It was largely because of his columns in the newspaper that I had an idea of what an extension agent was and considered this as a career possibility. When I was getting ready to go to school in horticulture, I contacted him, and he took me around and helped me understand what was involved in being an extension agent. I recall one of the pieces of advice that he gave me: If you don’t know the answer, acknowledge it, and say that you’ll find it. I have followed this advice many times.

For my couple of Washington Parish articles, I want to address something that encompasses much of what people need to know about gardening and landscaping: the “right plant, right place” principle. Fall is generally the best time to plant trees and shrubs in Louisiana, so this is information that can be put to use soon.

“Right plant, right place” means choosing plants that are well suited to the site in which they are to be planted. This includes selecting plants that are well-suited to our climate, including our temperatures and the amount of rainfall that we get. It also means appropriately matching plants to the conditions of particular spots on our property.

Many gardeners are aware that our climate is too hot for some plants to thrive here for a long period of time. Lilacs and most raspberry varieties are examples of plants that aren’t likely to tolerate our heat very well.

While it may have been hard to imagine it over the past couple of months, our area gets too cold for some plants. Bougainvillea, for example, can be grown as an annual or planted in a container and protected during the winter, but we probably won’t be successful in using it as an evergreen hedge, as people in some tropical areas do.

One way to get an idea of whether a plant is suited to the temperatures that we experience is to look at the hardiness zones for which the plant is recommended. US Department of Agriculture (USDA) Plant Hardiness Zones indicate the expected minimum temperatures for an area. Washington Parish is in zone 8B, meaning that the average minimum temperature over a semi-recent thirty year period was between 15 and 20 °F. So if a plant is listed as hardy in zones 9 to 11, it is likely to eventually be killed by the cold.

While USDA Hardiness Zones are based on minimum temperatures, they are often used to indicate the heat tolerance of a plant, too. So, if a reliable source of information says that a plant is hardy in zones 5 through 7, that plant probably won’t take our heat very well.

Information about what hardiness zones a plant is suited to is often available on plant tags, in books, and on websites about plants. OnlinePlantGuide.com, which has information put together by a couple of now-retired LSU professors, is a good source of information about the growing requirements of many landscape plants.

Besides tolerating our coldest temperatures and our heat, for some types of fruit plants the number of “chilling hours” we experience is also important. Many plants need a certain amount of exposure to cool temperatures in order to break dormancy, flower, and produce fruit.

Chilling hours are calculated in different ways by different people, but two of the most common ways to calculate chill hours are hours below 45 °F and hours between 32 and 45 °F. In Washington Parish, we can expect to get at least 500 chilling hours in a typical year, by the below 45 °F model.

When shopping for fruit plants, it’s sometimes hard to compare apples to apples (no pun intended) when it comes to chilling hours, since it’s not always clear on which model the stated chilling hour requirement of a particular variety is based. To make it easier for you, suitability to the amount of chilling we get is one factor that is accounted for in the recommendations found in, for example, our Louisiana Home Orchard publication.

For example, the ‘La Festival’ peach, which was bred in Louisiana, requires approximately 450 hours below 45 °F, while ‘Contender’, a variety that was popular where I used to work in North Carolina, requires approximately 1050 hours below 45 °F and is not recommended here.

Last year, someone saw ‘Belle of Georgia’ and ‘Elberta’ peach trees for sale for a low price and asked if those would be okay for Tickfaw. Both of these varieties require about 850 chilling hours, so the answer was no. While these may have been for sale for cheap, they would not have been a good deal for Tickfaw or Washington Parish.

While it may seem that as long as fruit plants get the minimum number of chilling hours required, they should produce well here, this isn’t necessarily the case. As you know, temperatures are not consistently cold during the winter here. If plants get their required chilling hours, and we get a warm spell in January or February, they may start flowering. Then, when we get another freeze, those flowers – or the fruits that have developed from them – are likely to be killed.

Using another peach example, ‘Flordaprince’ requires approximately 150 chilling hours and would likely bloom too early here. Likewise, while ‘La Festival’ is likely to produce well in our area, now-retired LSU fruit crops professor Dr. Charlie Johnson once told me that it only produced fruit about half of the time in Calhoun, which is in northern Louisiana.

Besides peaches, apples and blueberries are among the other fruit crops for which the chilling hour requirement is an important factor in determining which types grow well here.

Next week, I’ll address other considerations for choosing plants and deciding where to put them.

Contact Mary Helen.