The Kerby's Houseplant Shop E-Newsletter
February 17, 2022
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Houseplants 101  |   New Arrivals added at 12pm EST
The Science of Heat Packs
by Joey Bokor

By now, you know that we include a complimentary heat pack in packages heading to areas that are experiencing near freezing temperatures. That's been a lot of you over the past few weeks. This has definitely been a cold winter, even for us here in Florida.

My daughter nudged the science geek in me last week when she asked how the heat packs actually keep the plants warm. I had to sheepishly admit that I had no idea. I mean they get hot when you break the seal on their packaging, but why? Intrigued, I dug into it a little and figured that you might want to know too.

The ingredients in the heat packs that we use are pretty straightforward: Iron powder, activated carbon, wood powder, vermiculite, salt, and water. And it turns out that it is a simple chemical reaction that causes heat to be produced and it is the same process that causes things to rust. Here's what happens when a heat pack is opened. Air, and more specifically oxygen, reacts with the iron powder, creating rust or iron oxide. Activated carbon holds water that is needed for the chemical reaction to occur and salt acts as an amplifier to get the heat going. Vermiculite and wood powder help to spread the reaction out and insulate the heat packs so that the heat is diffused evenly.

Pretty cool, isn't it. This same reaction is used in MRE kits to heat food in the field and in hand or foot warmers, which keep you warm when skiing, hiking, or in other cold conditions. A simple rusting reaction is enough to warm a box full of plants. Just another reason that the natural world is a fascinating place.

Some fun new arrivals will drop at noon ET today, get a sneak peek of some of the items below. And with the power of the natural world, even in cold conditions your plants will still arrive safely to you. Happy Planting.


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