fruitnut
Do you mean the fruit buds formed (after current year harvest) for the next year when you say "some fruits chief amongst them sweet cherries can't hold fruit buds in good condition with that long a summer" ?

ottawan:

I can already see next years fruit buds forming on all my stone fruit including cherry. Since I begin chilling Nov 1, that's almost another 7 months that those buds have to hold until cool/cold arrives. I'm saying I think that's stretching the limits. So I'm planning a longer chilling period, a more gradual warmup in spring, and an earlier cool down in fall.

Cherries are better adapted to climates where nearly half the year the trees are without leaves.

A greenhouse in a colder and/or cloudier climate likely wouldn't have this issue. At least not unless someone pushed the limits by heating in winter.

I'm going to get the two low chill cherries from Zaiger and try for two crops a year. They barely need any chilling at all and with the right setup are easily capable of that schedule.

I think the really low chilling fruit is probably capable of handling a long summer.

My theory above is just that at this point.

Fruitnut, it does make sense. I have had cherries completely defoliate in August and go dormant, but come back full guns blazing next spring -- they seemed to almost prefer the short summer.

The only other explanation I can think of is it has something subtle to do with the chilling hours/temps, the chill hours model is always just an approximation to what the tree really needs. In other words the buds may never be forming correctly due to lack of some notion of chill. What is the season of the commercial cherry orchards in the San Francisco area? The bay area has a very long summer season and had many commercial cherry orchards and it would be interesting to compare with their season lengths.

Scott

Scott:

I've gone thru all sorts of explanations in my mind and discussions as to the cherry issues: lack of chilling, rootstock, too hot during flowering, and virus infection. I think this is the best theory so far. Here's another observation that supports the too long summer theory: the sweet cherry flower buds swell up in fall to stages that should occur after chilling. This theory could also explain the flower bud abortion I've seen in pluot. I'm certain they get enough chilling.

In 45 days I'm getting about 800 Utah chilling hrs. That should be enough for almost any cherry. In 90 days I can get 1000-1200 on a relaxed schedule at lower cost.

When I go on fast track 45 day chilling, my warm season is two months longer than any place growing cherries in CA.

It's also worth noting that no place in CA to my knowledge grows self fertile sweet cherries. Some of the self fertile have the most problem in my setup. I think the self fertile gene carries some linkage to the issue of bud development.

fruitnut,
-- Just like to say that I enjoy your interesting posts, and what you're doing is inspiring. I don't have a greenhouse, and some of what you grow is successful here in the ground (despite late frosts there are small time commercial orchards of apple, peach, apricot, cherry, plum in the area), but I am trying 4 potted pomegranates overwintered in the garage, and right now they're loaded with flower buds and growing well on the south side of the house. Thanks to your posts, I might try this method with other fruit trees as well...

I like your theory better, but another possibility might be lack of chill hours. I have read, although I certainly don't know, that a very abrupt switch from warm to very cold temperatures doesn't trigger the necessary chill hour "timer" On your expedited schedule, do you pretty abruptly throw open the windows to the cold air, or do you cool down gradually?

koko:

In the past I've gone pretty abruptly both into and out of chilling. So in addition to a longer chilling period I'll be making the transition less abrupt.

Chilling is brought on by shading and running the evaporative cooler all daylight hours. Without 36 inch exhaust fans and the cooler pad it would be way too hot inside during the day all winter for chilling. It does cool off at night mostly in the low 30s. Abundant sun most days all winter requires cooling but makes great conditions for fruit trees and fruit quality.

fruitnut:

I see it has taken you seven years to reach success but how old are the trees in your photos? Your yeild looks awsome.

I haven't had much success yet but am encouraged. I am in So. Cal. in Santa Clarita at about 1800 ft level so my chill hours are low but there are some great cherry farms not too far from me.

I have a Stella that was planted in 09 that just blossomed for the first time this year but has no fruit. I have a Bing planted later in 09 that has a few flowers but it rained just as they were opening. It has no cherries either. I have two Royal Rainiers that had a lot of blossoms but because of the Bing I only have about 5 cherries on them. They were just planted 2/10 though.

They are all in ground and I am hoping to get better results with time. My other fruit tree are doing great though. Katy, Dapple Dandy, Santa Rosa, Cotton Candy and my apples have many fruit growing.

Oh yea, your greenhouse is huge. Good luck with your season.

Chris

Are you tightly controlling the chill degrees? I'm very impressed that you can even add that much "winter" with just evaporative cooling. When the trees are bare/dormant do you cover the greenhouse to shade it and help the coolers?

I just heard a talk about another insect pest affecting berry crops. The way things are going you'll either have to spend all your time spraying or netting or bagging fruit in order to get any sort of crop. Greenhouse culture - even in areas that historically grew that crop - may be the way of the future for fruit production.

The trees in the photo are potted. They were grown outside about two years and I couldn't get anything on Gisela 5 to grow outside. This is their second year in a 15 gallon pot. They have grown much better in pots in the greenhouse than outside. I actually thinned off about 1/3 of the fruit that set.

During chilling Extenday reflective fabric is suspended on the trusses over the trees to help keep the heat above the trees. A shade cloth outside would be even better but that requires 42ft by 54ft just to cover the poly.

In the past I've tried to keep the temperature between 37 and 54F. The heater maintains 37F fine and most winter nights are that cold. Most days the high is between 54 and 60F when running the cooler pad and two fans. This next winter I'll probably run the heater at 34F to save a little money. The Utah model gives full chilling credit between 37 and 48F, less between 34-37 and 48-54F. Negative chilling above 60F. So yes I've controlled chilling closely to achieve Utah hrs. In a cloudy or cooler climate, winter chilling would be easy compared to our sun and warmth.

In Dec and Jan I can average about 19 Utah chilling hrs per day. In Nov and Febr about 16 hrs a day. So that figures out to about 480-570 hrs per month or 2100 hrs for the winter if needed.