Louisiana Irises & Poinsettias

Karen Cambre, Sharpe, Kenneth W.

News article for September 25, 2017

Louisiana irises are very popular. Even though they are dormant now, it is September and early October that is the best time to divide them. You can start new beds or share.

Dividing is easy. Dig up a clump of irises; just be careful not to damage the rhizomes. You are looking for the new rhizomes to plant. You can tell the new ones as they will have green foliage at the tips. Cut the new rhizomes way from the old rhizomes. Now plant the new immediately back into the bed or in planting pots and discard the old.

Plant irises by placing rhizomes horizontally, just below the soil surface and space them out 8 to 10 inches apart. Leave the top of the rhizomes just above the soil line. Mulch and water thoroughly.


Christmas seems like a long way off in these first official days of fall, but if you have kept poinsettias alive and want them to have color it is about time to get to work.

Keeping a poinsettia alive is only half of the battle, now the trick is to get them to show color in time to be a part of your Christmas decor. If you lived in a remote area with only natural light this might be easy, but you do not. You might know that a number of species in the animal kingdom are influenced by day length. An example could be chickens; they produce more eggs in longer days of the year and reduce egg production on decreasing day length. In the opposite way poinsettias have a dark period requirement that initiates their color. With chickens we have to turn on lights and with poinsettias we have to turn off lights to control the hours of darkness.

We used to have 6 or 7 poinsettia producers here in the parish in the early part of my career. Each one had their own nuances for how to bring poinsettias into color, but basically they would all start about October 5-12. They would increase the dark period and this schedule would have the poinsettias ready for sale in early December when most people were decorating for Christmas. Growers would leave the plants on the dark period schedule of 13-14 hours of total darkness every day for 40 days. Any interruptions in the dark period will delay color.

Artificial light is the enemy here. Most of us have a hard time getting rid of all lights. There are security lights at night, car headlights and even lightning storms to contend with. The obvious problem lies in the common light switch. Switches are removed or taped up during the increased dark period to prevent accidents. Growers will cover greenhouses with shade cloth and place houses in an area without outside security lights. They also have to make sure that cars cannot approach in a direction to point their head lights at the greenhouses.

It is possible to meet the extended dark period inside a spare room or closet in the home but it takes a lot of attention to detail. You can have no light coming through cracks under or around a door and you will have to take the plants in and out every day.

If you get too much light, your plant will stay green. If you are successful, the lower bracts or modified leaves will be brightly colored as they were when you purchased the plant to decorate your home.

You have kept that poinsettia alive for a long time, now just one more hurdle.

For more information on these or related topics contact Kenny at 225-686-3020 or visit our website at www.lsuagcenter.com/livingston.

5/9/2018 4:25:20 PM
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