Here is one way to create a cooler microclimate effect:
This is the hedgerow down the hill, on the coldest part of Ladera Frutal, where I have my corralito planted with deciduous fruit trees. In a low-chill region, one can maximize one’s chances of getting fruit by “cheating” on the chill hours. One way to do that is to plant one’s highest-chill varieties (like the cherry and apricot varieties depicted here) in an area where they will be shaded in the winter. Naturally, one has to avoid the trees’ being shaded in summer, when sunlight is needed to ripen the fruit.
One way to accomplish this is to plant close to taller evergreens, as with the mature Marsh grapeftuit trees than can be seen on the exterior of the corralito. When the sun is low in the sky, as on this first full day of winter, only the tops of the trees will be in sun. But when the sun is higher in the sky in summer, three trees will be bathed in sunlight except at their very low back sides.
The hedgerow style of planting itself helps with the chill, because the dense planting trees help trap cold air (further aided by the groundcover seen here), while the dwarfing that results from the trees’ crowding one another keeps most of the fruiting buds low to the ground. The ground remains significantly colder in winter than the air a few feet above. After I prune this hedgerow in the coming weeks, all the trees will be shorter, as I will leave only the low branches.
Along this hedgerow, the overnight temperatures often can be a degree or two colder at night than is the case out in the open, and the shade keeps the daytime high a few degrees cooler, too. A few degrees here and there, over three months, can add up to a hundred or more chill hours, making the difference between no fruit and a good set on varieties marginal to one’s climate.
Frost, then hot
I often say the weather is weird here. Well, this morning there was a light frost down below, near the corralito. Then this afternoon it was 85.
Scion grafted by Fruits and Votes — 06 February 2006 @ 17:54
Half a year of Fruits and Votes: From ‘The Last Pluot’ to wondering if we’ll get any pluots this year
Some varieties of pluots need 500 hours, and so we might have a lighter crop this year. It is possible that my “cheating” on chill has allowed the row closest to the taller grapefruit trees to have obtained closer to 500 hours.
Scion grafted by Fruits and Votes — 11 February 2006 @ 18:07
Low chill cherries?
I have had both ‘Stella’ and ‘Royal Ranier’ fruit here, but then the winter after which they fruited probably experienced 550-600 chill hours at the bottom row where I “cheat” on chill.
Scion grafted by Fruits and Votes — 21 February 2006 @ 16:32
Frosty
This the most frost I have seen in the corralito, where our highest-chill fruit trees grow, in five winters. (Well, that first winter, the corralito had not yet been built, nor any trees planted.) A lot of people who want to grow deciduous fruits assume you need to have frost. You don’t; in fact, the prime temperature range for the accumulation of needed chilling hours is about 38–45, Fahrenheit, and obviously frost occurs at lower temperatures. And when it the air temperature is at freezing, the buds’ receptivity to accumulating chill probably freezes, too, until it starts to warm up. Still, when the morning starts off this cold–the photo was taken around 7:30 a.m., when it was 31 degrees–the chilly air is likely to stick around, especially if you can give the trees some shade and if you are in a canyon or valley that tends to trap the cold air. Only by about 10:00 a.m. did the temperature rise above 45, and the high in the winter-shaded part of the corralito (structured so as to “cheat” on the chill) barely reached 60.
Scion grafted by Fruits and Votes — 20 December 2006 @ 12:58
Low noon
At 11:47 this morning was solar noon on the first day of winter. Thus even at the point of the day’s maximum sun, the higher-chill deciduous fruit trees in the southern hedgerow of the corralito, shown in the above photo, are mostly in the shade of the tall grapefruit trees (a few branches of which are just barely visible at the left). This dense planting of deciduous trees in winter shade is a “trick” to maximize the chill that they receive.
Scion grafted by Fruits and Votes — 05 January 2007 @ 10:00
Cold December, Hot January
What a difference 100 or so feet of vertical change over 200 or so feet of horizontal can make! And in the protection of the big old grapefruit trees, the hedgerow (where I cheat on chill) stays cooler still: the hottest day was 83, rather than 87 or 89, and it is almost always 1-3 degrees colder at night.
Scion grafted by Fruits and Votes — 17 January 2009 @ 00:27