Page 14 - Simply Veg 4 2022

A touch of frost
ADRIAN BAGGALEY
It’s the last week of March 2022 and Spring has arrived, we have altered the clocks, always an event for outdoor people. The weather presenters are telling me something I definitely don’t want to hear; and that is that Winter is coming back with a vengeance on the 30th and the wind is swinging around to the north bringing sub zero temperatures to the British Isles during the nights.
Radiation frosts I can just about cope with as my orchard is on a slope. Sunny days tend to mean clear skies and clear skies at night means radiation frosts, this
is when the heat absorbed in the ground during the day very quickly radiates back into the atmosphere at night, unless it clouds over late afternoon or early evening. The lost warm air at ground level is replaced by much cooler air often below zero, hence ground frosts. This cold air hangs around on flat ground, enclosed ground or low-lying areas; on a slope it runs down hill just like water, until it runs up against a barrier such as a fence, hedge or wall. The cold air then backs up and
can envelope tender plants and blossoms. Walled gardens for instance have gates in the walls to let cold air escape; otherwise, the walled garden could become a frost pocket. It is generally acknowledged that the presence of a body of water nearby creates an equitable climate for fruit. Historically, cooling air has always run down my plot and over the road to destroy other people’s fruit crops.
Radiation frosts are not the big problem in relatively recent times. Once we get into Spring and the ‘white’ blossom is out (plum, pear and cherry) the wind routinely switches to the north, northeast or east, these icy winds come from the Arctic, Scandinavia or Russia. There is not a lot that can be done. A wind break will lift
up the wind over the top of fruit trees,
even when there are no leaves on the
wind break, a great mistake of mine was pleaching (‘laying’) a eighteen foot high boundary hedge on the north side of the orchard, hind sight can be a great thing, this overgrown hedge minimised the air frost problem. Some fruit tree systems
like espalier and cordon culture can be grown against walls and fences. Walls radiate back heat that was stored up during the daytime, on a south facing wall this generally works quite well. Fences don’t really store up any appreciable heat, when the sun goes in they quickly discharge heat. They are of course fairly easy to fasten a cover too, like fleece, tarpaulins or lean another fence panel in front of the blossom. Fence panels should be around nine inches to a foot above ground; this allows cold air leading to radiation frosts to seep away. With air frosts the gap requires blocking up. An example of what you are up against was 2012, the end of May saw the wind change to the north east, this really was the Beast from the East, air temperature plummeted during the night and a severe air frost wiped out just about everything. So even
in late May fruit growers are not out of the ‘wood’ when it comes to frost; perhaps I should say not out of the ‘orchard.’
Back to the 30th of March (2022), I spend all day spreading out and cutting horticultural fleece. The first blanket, two thicknesses of 30gr fleece are wrapped around the Asian Pear, Seuri. This pear has never cropped due to its early flowering;
I have been tickling the blossom with a rabbit tail for nearly three weeks, although this year there were a few honeybees and the odd bumble bee about. The apricots
Baby ‘cots’
Young pyramid Jargonelle pear
and peaches have also been tickled, for around three weeks. Last year, tragically all were wiped out by air frost. The Japanese plums at the top of the main orchard have also been hand pollinated for weeks with a rabbit tail on a four-foot stick; these are overgrown trees so there is no chance of covering them. There is a lot to lose.
Blanket number two is wrapped around a Mirabelle in a 35litre ‘Tree’ bucket and blanket number three, a huge ten metre long by three and a half metre wide double skin 30 gr fleece is tacked to a series of panel fences with four espalier pears against it. These pears were just starting into blossom; all this gives some relative peace of mind. It could be said that the rest of the orchard is on its own, but I have other ideas.
31st of March, the alarm clock didn’t
get to go off, I was already up and out of bed at 04.30, I make a quick flask of tea and clear some horrific ice off the van windscreen and head for the plot. As I arrive and get out of the van, I hear Charles (the plot pheasant) announcing his arrival at ground level although it’s still pitch black and bitterly cold, he has six ‘girls’ to keep an eye on. This tough old bird sleeps in
the top of a bare twelve-foot overgrown hawthorn hedge all Winter from four p.m. in the afternoon through to around seven a.m. the following morning, around fifteen hours, taking the brunt of all weathers.
Two knapsack sprayers have previously been filled with tap water and left in the greenhouse, ready and waiting. I don’t even have time to look at the thermometers - I know it’s freezing, although I don’t see any brass monkeys.
The first trees to be sprayed are two Haganta plums in the corner of the
veg beds, and then it’s the turn of the polytunnel, two apricots, Tomcot and Alfred
30gr fleece blanket protecting the Seuri Asian pear. No not a tree fern.
14 Simply Vegetables