Warm water protection experiment on Parajubaea - Your input.

[GREVILLE]

Just before the arrival of the current freeze I put some blanket protection on my young Parajubaea Torallyi (PTvT) which I'd planted out last Spring. After a couple of threads on putting bottles of hot water under covers drew varied comments, I thought I'd test this out on the palm and record the results.

Instead of just giving a boring list of stats, I thought I would introduce the set-up of the experiment on the first post. Then before showing the results on subsequent posts which I'll supply this evening, I want to flavour them with answers to any questions or comments members may have. If you want to put forward any suggestions to continue the experiment, I'll try to follow these up, if practical. (Bit of an experiment in itself - this )

The PTvT is a 'double' plant of a young seedling next to a more mature pinnate leafed palm, giving the impression of a suckering plant. The younger seedling was more active into the winter. It is planted on a raised bed two feet away from a south west facing house wall and here it gets almost complete shelter from winds between north and south-east. It can also get uninterrupted winter sunshine from around 10AM till dusk. To illustrate how warm this border is, a bowl of water against the wall will only begin to freeze when the temperature has fallen to around -2c in the coldest part of the garden.

The protection consists of a wigwam arrangement of 6 foot canes over the gently tied up palm. Two blanket covers are used. The inner one is a light, nylon-based thermal blanket that is weaved to allow airspace in it's tiny square holes and the outer blanket is a standard cotton type. The blankets are draped over surrounding soil about eighteen inches from the base.

These were placed on the palm at dusk on 30th January. The day had been cloudy
and the maximum was +4.6c following an earlier minimum of -0.7c. Before the blankets were positioned the temperature probe was placed into the spear of the larger palm as close to the growing point as possible. After a few minutes the temperature read +4.5c. No warm water was used overnight.

The weather overnight (31st January): Cloud cleared and temperatures dropped from +2.0c at midnight to -2.8c at 0630. 0800, freezing fog had formed, temperature -0.9c. At 0900 the temperature from the coldest part of the garden was 0.0c.

At this time the PTvT was inspected.
The temperature outside the blanket was +0.5c and the probe still placed into the spear read +3.0c. The bowl of water on the bed eight feet away had a thin layer of ice.

Day two, to follow. In the meantime, post any questions or comments.

[GoggleboxUK]

Next! We need the result!

[GREVILLE]

Day 2, 1st February

Min temp: -1.6c , Max temp: +3.8c

Sunny spells during the day raised the temperature under the cover but no reading was taken until 1900hrs when the temperature outside was -0.8c and the probe above the growing point inside registered +5.5c

One 1.5 litre bottle and one 5 litre plastic canister were filled directly from the hot tap (the temperature of the water was not taken at this point). These were wrapped in a double layer of cotton material (old vests from the rag bag ) to slow the release of heat and placed under the cover, the bottle on its side and the canister upright either side of the palm.

Into day 3, 2nd February,

Min temp -3.1c.

At 0800hrs the temperature from the weather station was -2.5c.
The temperature outside the cover was -2.0c and from inside it was +5.5c.

This was a slightly colder night than previously and with the inclusion of the warm water slowly radiating its heat for 13 hours the temperature inside the cover was a good 2.5c warmer than 48 hours earlier.

[GoggleboxUK]

Brilliant! I've been a firm believer in this method all along and these are exactly the sort of results I expected, although I'd imagine that if temperatures had been colder then replacing the warm water after 8 hours would have become necessary.

I'm pleased to hear that the wigwam actually retained the warmth of the day's sunlight too, that's an unexpected bonus.

I've been waiting for some substantial cold to conduct similar experiments myself Greville but, fortunately for me, I haven't really suffered any serious cold so far this year.

If I can make a suggestion would you try wrapping the top two thirds of your wigwam with a thermal blanket and see if that retains more heat or prolongs the cooling time within the water containers.

[GREVILLE]

Sorry, Rick, I hadn't realised you been posting while I was editing my second entry. I started this a bit late and I was slowly becoming brain-dead translating my notes and making errors into the bargain

I'm going to add more figures from the following days with some extra readings of the water temperature before and at the end of the night.

The top of the wigwam being narrower has the blankets wrapped around twice, in effect four layers, compared to two lower down spread round a wider girth. Are you wanting another layer on top to trap more of the rising warmth?

[GoggleboxUK]

Yes, the tinfoil type thermal blankets are said to reflect 97% of heat so I believe that, as the heat rises in the wigwam, having this additional layer trapping heat and also reflecting cold from outside (natural material won't do this) should create a much more efficient 'heat trap' at the top of the cone.

This in turn should also create a warmer environment for the containers as the greater volume of heated air will effectively slow the heat loss from the water.

[GREVILLE]

The 3rd and 4th of February were the coldest nights before the arrival of the snow. Before that the days were sunny and a sample reading around 1400 on the 4th showed a temperature of +1.8c from the weather station but behind the covered palm the shaded probe was recording 11.0c. The suntrapped micro-climate given the PTvT was doing its job. Just putting my hand on the warm red bricks was very comforting with the knowledge that all that heat would radiate back out overnight.

When placing more warm water in the containers I noted the temperature from the probe placed inside read 50.5c, so hand hot and these were sited late evening.

The morning of the 3rd had a minimum of -3.3c. The probe under the cover read +4.0c.
The 4th recorded -5.5c and the temperature inside the cover read +3.0c.

The temperature of the water in the 1.5 litre bottle read +4.5c and the 5litre canister read +7.5c on BOTH mornings ten hours after siting.

[GoggleboxUK]

How long had the water been out there Greville? 13 hours again?

They are excellent results, a real plant saving difference.

I'd be interested to see what happens with outside temperatures going below -8c but I don't wish that sort of cold on your garden. It's more likely I'll see those temperatures next year.

[Yorkshire Kris]

Just thought I'd saying that I am finding this thread interesting.

[GREVILLE]

Thanks, Kris.

Appropriate, then that I put on some information that is particularly interesting. I want to jump to the temperature readings from last nights exceptional cold. (Bit short of time at the moment to put in all the details to date.)

I put the warm water out quite late last night at 2300 with the temperature already down to -3.2c. This time I put a third blanket on the wigwam and a third layer of cotton based fabric around the water containers, hopefully to keep the temperatures inside higher for longer. I should add at this point that the 5 litre plastic canister is NOT insulated on the bottom and this stands directly on the soil surface about six inches from the base of the palm.

Last nights minimum here was -7.3c. At 0800 this morning I took the ambient temperature just outside the covered palm and noted a reading of -4.5c. This was nearly 3c warmer than the reading from the weather station ten metres away in the open back garden where it was still -7.2c.

The temperature inside the top of the wigwam cover was +11c .

I measured the temperature in the water containers after giving them both a shake. The 1.5 litre bottle read +9.0c and the 5 litre canister read 19.5c

Having taken out the warm water and disturbed the covers I took more readings a few minutes later inside the wigwam. At the top it had dropped to +8.5c and the soil temperature where the canister had been placed read +9.5c.

My only comment is that I was gob-smacked that one extra layer of insulation around everything should make such a difference.

[GoggleboxUK]

Excellent results Greville, well done!

I think we could benefit from some pictures of the wigwam and some dimensional measurements. Obviously the smaller the internal space the easier it is to heat and I have no real concept of the size of palm you're orotecting.

[Yorkshire Kris]

I am pleasantly surprised.

[Rick1965]

This is a really interesting post, well done. Do you think the lack of air flow would be a problem if you used this technique for say a month?

[GREVILLE]

Can't pass myself off as some science boffin - I've just realised I've made another gaffe For 5 litre canister, read 10 (TEN) litres (Spotted the difference this evening when putting in windscreen wash from a real FIVE litre canister!

First job returning home tonight was to put more hot water in the containers (Temperature at +49.5C) but I've removed the third layer of insulation from the covers and containers to compare this mornings results with tomorrows on what should be a night of similar temperatures. (I'm expecting -5c to -6c.) Current temperature at 2300hrs, 10 metres from the experiment is -3.7c

Gog, I have to sweet-talk my beloved to borrow her brand new camera. (Don't know how to use it, yet). Might get some explanatory pictures made up tomorrow. Don't have a thermal blanket of the type you describe. The inner cover is an 'underblanket' that assists with 'thermal insulation'. I used an additional thick but lightweight brushed nylon blanket on the top two-thirds of the arrangement as an inadequate attempt to realise your request, but it seemed to do a good job nonetheless

Rick, I think the blankets I use breathe enough to change the air, especially when I open the blankets to change the water. When there was strong winter sunshine on the arrangement the ambient temperature around it was well above freezing so on a couple of days I 'opened the curtains'. The inner blanket never gets wet even when the outer layer was soaked from snow melt. I imagine this set-up would work well under one of Dave's parasols.

[GREVILLE]

At 0900hrs this morning after a night minimum of -5.6c and two layers of protection on the water containers and wigwam (had three layers on each yesterday) I recorded the following:

0900hrs weather station reading: -2.2c
Ambient temperature outside wigwam -2.0c
Temperature inside wigwam: +5.5c
Soil temperature inside wigwam (under canister): +6.5c
0900 hr temperature of 1.5 litre water bottle: +4.0c
0900 hr temperature of 10 litre canister: +8.5c

Aside from the difference in temperature caused by the removal of one layer of protection, the immediate temperature around the wigwam was almost the same in the coldest part of the garden. A slight southerly breeze was stirring the air and the radiating warmth from the nearby wall was no longer effective.

The breeze also seems to have contributed to about a 1c drop in the other temperatures compared to two days ago. No wind has blown on the wigwam till this morning.