Heating Your Greenhouse in Europe This Winter

Started by Bern, September 03, 2022, 09:59:17 AM

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Robin Hansen

Jane makes a good point about plants getting leggy. Generally I move the plants needing more light out in very early spring, but for now the greenhouses are mostly full of primulas and seed trays. I've found some crocus and narcissus do better if they winter over in the unheated houses.

I just can't imagine surviving in AK in winter. I suffer enough in the dark of winter on the coast although it's better 200 miles south of Portland where I used to live.

I do wish radio stations hadn't become so automated. Now, you have great difficulty finding locally news broadcast a few times a day, and weather reports are bare bones so it's better to listen to NOAA, all this because we have the most pitiful excuses for local newspapers these days...
Robin Hansen
President, PBS


It's going to be extremely cold in the midsection of the USA all of the way down to the Gulf of Mexico this coming Friday night. Folks with greenhouses will be challenged to keep them heated if there are natural gas shortages or rolling brownouts or blackouts of electrical service. Low temp records are sure to be broken and Friday is only day 3 of winter. This will make some people global warming skeptics - at least until the heat of next summer is upon them, especially in south Texas.


Robin Hansen

We are lucky here in the Coquille Valley (about 14 miles east of the Pacific Ocean) - the low 20s temps have been ongoing for about 3 weeks with not much increase during the day. I've been watching for signs of damage in the potted nursery stock and so far so good. The gradual cooling is always best and we're a good 10-20 degrees below normal for this time of year, although this habit of saying normal ought to be thrown out on the compost pile.

At the same time, the one enclosed greenhouse with doors shut and under roof ventilation vents permanently open (designed that way) is routinely 5 degrees warmer than open air. Even the alpine house, so-called, which has double-wall siding (opaque, not polycarbonate) is warmer by 2-5 degrees. I can't moan and groan if all this cold means our water supplies increase, although economically there's always a negative impact in some way.

I listen to the local NOAA weather reports and the winters in the 1920s, at least in the west set all kinds of cold records that still exist. My mother as a young child lived in Portland, OR and it was common for the Columbia and Willamette rivers to freeze so solidly that people would drive their Model As and wagons out over the river. In the winter of 1978-79, in Boardman (up on the Columbia), we had a total of 3 feet of snow from Oct. 31 to the end of March and the river froze over where it's three miles wide. It was not hard enough for driving on since the dams widened the river considerably after they were built. Nothing like that has happened since.

So these wide swings have occurred in the past but seem more frequent and increasingly more severe, just from where I live.
Robin Hansen
President, PBS

Martin Bohnet

Germany has just survived a very cold weekend after an already quite cold week, and of course the definition of "survived" can only really be checked in spring - the nearly flowering Kniphofia sarmentosa
Height: 60-90 cm (2-3 ft)
Flower Colors: red, orange
Flower Season: mid winter to mid spring
Climate: winter rain climate
at least has lost the flower spike and I'll have to be very careful to keep the rootstock from rotting - especially as there WONT be frost for the next week - those swings are a hard blow against vegetation.

Saving is difficult when you have to heat against -11°C (12F), so I've got to top 3 in my 10 year overview in weekly electricity consumption and somewhere in the top 10 with gas. I still tell myself carbon footprint is OK as I didn't fly around in the last 20 years or so.
Martin (pronouns: he/his/him)

David Pilling

Two weeks of unusually cold weather - the coldest since the years of 2009 and 2010 when I lost a lot of plants. The difference to other years is sub 0C temperatures during the daytime (for many days together). Temperatures in the greenhouse got below zero C one night - despite my oil lamp. I'm hoping no damage done.

Min temp -6C - not Canada, but cold for here. All change today as temps around 13C.

Keeping the house warm has been stressful - using over 100 kWH per day of electricity.

No mention on the BBC of badly implemented net-zero being to blame for us now being poor.

The supermarket next door got a heat pump this year, this has been running non-stop through the cold, noisy enough to hear indoors. From observation it makes the surroundings colder - robbing heat from their neighbours.


If one of these arctic cold air incursions of this magnitude intrudes east of the prime meridian this winter, it will be a very serious thing for heating bills.  The one that will hit the US this week is massive and winter will have just officially begun. You can never predict what this means for the rest of the season, so we'll just have to take it a day at a time.

Some houses in southern NM have uninsulated water pipes entering their houses from outside of the foundation. I've seen these myself on houses from Las Cruces to Deming. These will freeze and break if they aren't drained before this cold air hits. This happened in 2011 during another record cold wave that included the loss of natural gas for heating. I doubt anything has changed to correct this since then.

Using 100KWH per day of electricity is quite a lot. I just checked my electric bill for November and I used about 19KWH on average for each day that month. It will be quite higher this month.

Hang in there!


David, what does a KWH cost in Blackpool? Here in Northeast North Carolina USA, it is about 9.5 pence sterling or $0.12 US dollar.


Energy charges are variable to some extent, depending on supplier, and follow a complicated method of setting them in the UK. The whole UK operates on the same system/prices but maximum prices are set by a quango.

At the moment, electricity is around 19p per kWhr, gas is around 10p, but they are indirectly linked via the method used to set wholesale electricity prices.


QUANGO... fascinating term/acronym, new to me. Thanks. Here in the USA, they swarm mostly in the Washington DC swamp.


Here in Williamsburg the cost of a fully loaded KWH is about 15 cents.  This figure was arrived at by dividing the total bill by the KWH.  There are many distinct line items in the bill such as transmission, distribution, generation, and taxes, etc.  I'm on a grid for a local nuclear plant. I just got their annual calendar that includes instructions on how to evacuate in case of an emergency. 

QUANGO, from quasi NGO. Sounds like a new aussie nickname for kangaroo. I much prefer the kangaroos.


It's interesting that Robin Hansen lives nearly 200 miles south of me, and closer to the ocean, but temperatures where I live are quite a bit warmer the past week or so. Just another example of why USDA climate zones (the 1 to 10 ratings) don't apply to the far western states.

David Pilling

Here in Blackpool (I doubt these numbers will be much different to elsewhere in England):

Electricity 48.88p/kWh less the energy price guarantee 17p/kWh plus 5% VAT equals 33.4 pence per kWh

Gas 14.05p/kWh less the energy price guarantee 4.22p/kWh plus 5% VAT equals 10.32 pence per kWh

There is a small additional "standing charge" per day.

The "price guarantee" is the UK government capping prices - borrowing and taxing and giving the money to energy suppliers. The average UK household is supposed to use around £2500 of energy per year after the price cap.

1 pound is 100 pence is US$1.21 today.

New governments traditionally have a "bonfire of the quangos" but the numbers keep growing.


David... We use propane gas to heat the greenhouse. The last delivery worked out to $.11 USD per KWH and factoring in the heater efficiency, $.13 USD or about 10.7 pence sterling per KWH.

Judy Glattstein

We have an in-ground 1,000 gallon propane tank that fuels kitchen stove, hot water, heat for house and greenhouse. Clothes dryer uses electricity as it vents to garage (hey, we didn't build the place.)

With the very low temperatures forecast for the end of the week my husband installed the auxiliary electric heater that was used last winter. Smallish box unit suspended about 4 feet off the floor. It's at the opposite end of the 8 ft by 18 ft greenhouse from the gas heater. Basically, I turn it on after dark, setting its thermostat so it just comes on at appropriate temperature before it drops even more at night. There is bubble wrap on all vertical glass to ground walls.


Going back to the mention of semi-underground greenhouses, yesterday my exploration of ancient AGS journals turned up an article on how one English gardener in 1941 dug a bomb shelter in his back garden, and was inspired to use the angled sandbags-on-metal cover to add a few rocks and a lot of plants to create what might be called an artificial moraine. Nothing can stop a mad gardener -- not even the Blitz.