On February 14th of 2021 Texas Weather lost it's ever-loving mind.
Texans are accustomed to weird weather and duplicitous forecasts, but nobody expected 8"-10" of REAL snow to fall in 30 hours and remain on the ground for two full weeks. This does not happen in OUR zone 8 neighborhood. In over 43 years of living in Texas I do not recall it ever happening like this before.
So, as a gardener that lost HUNDREDS of potted plants, and more than a few established plants in my landscape, I am now keenly aware of the upcoming frost date of November 11th, 2021. This is the date that our trusty, ole' Farmer's Almanac predicts to be the first light frost of the Fall/Winter in 2021-2022.
Farmers have been tracking significant dates like this with carefully crafted solar & lunar calendars going back aver 5,500 years. There is abundant archeological evidence that ancient cultures knew the equinoxes and solstices very well, they understood astronomical precession and they lived paying close attention to planting & harvesting dates. After all, when it comes to growing healthy and productive plants timing is everything! Humans have always liked to eat.
While the almanac says November 11th, other sources closer to home predict it could be as early as October 29th this year. Most of these prognosticators are also suggesting a colder winter than usual (solar minimum?) so it is important that we protect the sensitive things we want to keep healthy. Now would be an excellent time to gather together the frost protection you are likely to need and make plans to relocate the potted plants that require warmer conditions.
I will be working hard this weekend to close up the remaining openings on our production greenhouse to make it as draft-free as possible. 4x8 panels of rigid foam board are a light, flexible, and relatively inexpensive way to provide some additional temperature protection to an existing garden structure. UV safe plastic sheeting, hoop houses, and even bed sheets can all be employed in our strategies to keep plants warm. The most dangerous period of time for sensitive plants is between midnight and daybreak. This is when ambient temperatures fall the lowest and when anxious gardeners are usually fast asleep in their beds.
Open flame or unattended flame is NOT the safest proposition for heating greenhouses, garden sheds, garages, or even make-shift structures built to shelter plants. In the past I have made some terracotta heaters using old, clay pots and cans of sterno...but I do not recommend anyone try this if you have other means of safely generating heat. I want y'all to be safe and not take the risks I have taken. Hopefully, some of you can benefit from the painful lessons I have learned.
Electric heating is probably the safest method of maintaining a safe air temperature but it pays to be careful and think through all the different ways your setup might fail you.
Electric heaters should have built-in tip protection that shuts them down if they get knocked over and they should always be plugged into an outlet with GFCI protection (Ground Fault Circuit Interrupt). GFCI outlets are required by code for all exterior outlets and they provide protection by cutting off the flow of electricity when a grounding fault is detected in the line. This is a minimum safety measure.
Examine your extension cords carefully to make sure the plastic insulation is in good shape before you rely on it. If it is spliced anywhere, cracked, or the 3rd ground-pin has been removed from the plug end then DO NOT USE IT. Honestly, use a new cord. Wet soil conditions, rain/ice, and the heavy demand caused by energy-hungry heaters can create deadly shock hazards with compromised cords.
Never extend power farther than 100' to an electric heater. Use a single cord long enough for the job so that you are not linking together multiple cords.
Make sure the copper wire inside the cord is adequate for the electrical load created by the heater. Amperages should either match or the cord should be heavier.
Make sure your heater is on a solid surface, such as a concrete block or paver, that will not tip and can not catch fire.
Make sure all combustibles (and all plants) are at least 4' away from the heater at all times - but I recommend you follow the manufacturer's directives here.
Heat travels upward and so it makes sense to think about how it will move inside your plant shelters and where it might build up.
This heat can actually hurt plants if it is not managed. Try to use a heater with a built-in thermostat that shuts off the heating element when it is not needed.
Heat will also melt snow and ice on the exterior of an uninsulated structure leading to water accumulation and re-freezing elsewhere. Water is heavy but it flows. Ice is also heavy , but it accumulates until it can become heavy enough to crush a structure or collapse a roof onto your delicate plants. Carefully consider how melted water will make its way off of your shelter.
It can really tricky to construct a water-proof, ice-proof, heat-safe, fire-safe, plant shelter out of junk you have lying around the house...so, maybe we should all take this weekend to figure it out before it's too late.
I hope this post is helpful to someone.
~ steve