We store our bug and weed killers in the garage, which is unheated. We want to know if, after these extremely low nighttime temperatures, these products will still be effective, or if we need to throw them out and start over.
Let’s start with the “bug killers.” Most liquid pesticide labels contain specific information on storage temperatures and will generally state a temperature in the 40–100 degree range. But, as you noted, we’ve had uncommonly cold temperatures so far this winter, and an un-heated garage or garden shed could easily have fallen below that range.
Freezing temperatures can cause the active ingredients in liquid pesticides to separate from the solvents, emulsifiers and other inert ingredients, making some products useless. Products that can be re-emulsified and reused will specifically state this on the label.
Check your pesticide containers for any damage caused by the cold. Glass, metal or plastic can all break in extreme cold.
For the most part, dry pesticides aren’t affected by temperature extremes. These products are more likely to absorb moisture from exposure to high humidity and solidify into hard masses (“tombstone formations”). The packaging can become brittle after taking on moisture, and, if freezing occurs, they can break when handled, giving you one more thing to clean up.
Check the Storage and Disposal section on the pesticide’s label for more specific information. If you decide that you should replace it, follow the disposal instructions you’ll find there to avoid contaminating soil, groundwater, and surface water. The University of Florida has an excellent publication (edis.ifas.ufl.edu/pi060) with detailed steps to safely dispose of pesticides and their packages.
Knowing whether or not to replace your herbicides isn’t quite that straightforward. Not every manufacturer lists storage temperature ranges on their labels. Nor is this information always posted on the manufacturers website.
But, generally speaking, you ought to know that herbicides containing petroleum products should not be allowed to freeze. Freezing will cause permanent separation. Other active ingredients may also lose the efficacy.
One ingredient found frequently in many non-selective herbicides (i.e., indiscriminately kills all plants that it touches), glyphosate, should be stored at temperatures of 40-80 degrees to retain its peak effectiveness.
The UF publication, “Storage Limitation Statements: Temperature-Herbicides” (edis.ifas.ufl.edu/pi160) includes a chart of commonly used agricultural herbicides registered for Florida – the trade name, common name, and the labels’ information regarding storage temperatures. Once you’ve found the active ingredient listed on your product’s label, this chart should give some guidance.
Is it too late to plant fall vegetables? My lettuces got zapped by the freeze, and my family decimated the kale we planted. But I know the weather will be warming up soon. Is it too late?
Not at all late. Just because we Floridians see blue skies and decide it’s spring, the rest of the country will be quick to tell you winter isn’t done with us yet.
The “Florida Vegetable Gardening Guide” (edis.ifas.ufl.edu/vh021) is the go-to for guidance on what and when to plant in north Florida. You’ll find that in addition to kale and lettuces, there are quite a few vegetables that we plant through February and harvest before the heat of summer.
In fact, in spite of the frosty mornings, my kale looks, and tastes, wonderful. We harvest the lower leaves, leaving at least two-thirds of plant intact and use them in salads, steamed, and even baked into chips.
There’s still time to start this ‘superfood’ from seed. Kale is not a terribly particular plant and it thrives in a wide range of soils as long as it has a sunny spot and regular watering.
Be sure to select one of the Florida-friendly varieties that include Tuscan or lacinato, “Dwarf Blue Curled Vates,” “Winterbor” or its reddish leaf cousin, “Redbor.” The two together make a lovely border planting that’s almost too good to eat.
My neighbors’ yard trash stacks are full of crape myrtle limbs. I didn’t know they had to be pruned and have no idea where to start. Will we be losing flowers if we trim them now?
You’re right. Crape myrtles typically need no pruning at all. But there are some instances in which judicious pruning will be a good idea.
As always, the first reason to prune is for the health of the tree. Look for any damaged or diseased branches. If you find branches crossing, prune out the weaker of the two. You can, if you want, remove the old seed pods, but leaving them in place does not affect next summer’s bloom. Remove any small twiggy growth from underneath and in the canopy to improve air circulation and help prevent powdery mildew.
If you do have to do some pruning, don’t worry about losing any of the dazzling blooms. Crapes bloom on new growth in summer, making late winter the perfect time to do any tidying up while the plant is dormant.
But please resist the temptation to heavily prune back the top of the tree, a practice called “topping.” Also known as “crape murder,” perpetrators of this high crime against horticulture will tell you it produces bigger blooms. In fact, the evidence indicates the clusters of flowers are thinner, and branches weaker and easily broken. It leaves the tree’s trunks out of proportion with its top. And, in conclusion, Your Honors, it can actually shorten the life of the tree.
You be the judge…a needless extra garden chore, or a healthier tree. I rest my case.
Paula Weatherby is a Master Gardener with the Duval County Extension Service and the University of Florida/IFAS. For gardening questions, call the Duval County Extension Office at (904) 255-7450 from 9 a.m. to noon and 12:30 to 3:30 p.m. and ask for a Master Gardener.