Plant pot heaters, do they work..?
We didn’t really get a frost last year. I agree we had a few
mornings that were white over on the ground but that’s about all. I say that,
not because I was looking at my pinecones or analysing weather data, it’s
because of my own observations in the garden. My frost tender plants survived
outside with no protection, I’ve mentioned before about my cacti and geraniums
surviving without any sign of frost damage. The frostless weather also meant
that a lot of slugs were free to multiply; it’s been one of the worst years for
slug damage for that very reason, chickens are happy though.
The frost also plays a big part in improving the taste of
certain vegetables and although we only got the touch of frost last year, I am
sure it was enough to make the broccoli taste a bit sweeter
.
Plants taste better
after a frost
Brussels sprouts, kale, mustard greens, cabbage, parsnips,
carrots, celery root, beets, turnips, rutabagas(swede and turnips) ,Kohlrabi
(German for cabbage turnip) and oca (New Zealand yam) all taste a bit sweeter
after frost. Leeks and celeriac also benefit.
Why is that?
When really cold weather happens, carrots parsnips and other
root vegetables convert some of their starch stores into sugar. They do this to
keep the water in their cells from freezing, and it works in the same way that
putting salt on a road keeps it from freezing over. When another substance
mixes with cold water, it makes it harder for enough water molecules to reach
the surface and freeze there. This lowers the freezing point. The cells inside
a carrot might have icy-cold water, but that water won't turn into ice, which
is a good thing as the formation of ice crystals within and around a cell can
destroy it.
There’s a more technical explanation if you want to impress
your friends. “Sugar accumulation in living and non-living tissues during
winter in cold-hardy plants has long been observed and is thought to be
important in cold acclimation because it increases viscosity, which reduces ice
crystal formation, helps stabilize membranes by binding to the free phosphate
groups of membrane lipids, maintains respiration in living cells, and allows
cell metabolism to recover after freezing." Just incase anyone asks!
The resulting increase in sugars makes them more palatable
for a lot of people. This post-freeze deliciousness will be true of any of the
vegetables that can survive a hard frost, including the ones I have mentioned
earlier such as broccoli, kale and celery. There are a few exceptions. Leeks
for example produce their sugars after dormancy and frosted potatoes can cause
carmelisation when they are being cooked which turns your spuds brown. I can
cope with that and I for one am hoping for a few harsh frosts this winter. Lag
your pipes!
Heat your home with a
tea light and plant pot -NOT
There are a lot of youtube posts and facebook entries popping
up promising to “Easily Heat Your Home or Greenhouse Using Flower Pots and Tea
Lights”. The idea is that you upturn 2 terracotta pots, of different sizes, one
inside the other and space them out with washers and bolts. These are put on
stands to allow air flow and then tea lights are put underneath to create a
“thermal heater” More and more elaborate designs are coming out but they all
have the same level of efficiency.
This concept has been around a while and seems to come back
every autumn as the weather gets cooler. Here’s an explanation of the science
behind the phenomena, and you can decide if it works for you.
A naked candle puts out a very small amount of heat into a
room (approximately 263 BTU/h or 77w), so you would need 19 candles burning to
equal the typical 1500w room heater.
But a flower pot makes it put out more heat, right?
No, a flower pot converts the candles convective (air) heat,
to radiant (body) heat. It also shifts the time period, as the clay takes a
while to heat up, and also to cool down. If you are sitting directly next to
the pot, you would feel warmer, but the room would take longer to heat up. Both
methods would bring the room up to the same temperature.
19 candles would incur sooting and corresponding lung
issues, so there will be a cleaner heating source. For comparison purposes, a
77 watt light bulb running 24 hours per day costs €0.18 (at €0.10 / kWh).
That’s cheaper than buying candles, a whole lot safer to use, and better for
your health. You could put it in a flower pot to give the impression of candles
burning if you like; I’ll put on a jumper and wrap my plants up with
horticultural fleece.
