Delaying fruit tree flowering

Here in Colorado, we need to delay fruit tree flowering. Generally, trees flower after a few warm weeks in March (or even February) only to get frozen in April. This is particularly bad with peach, apricot, and cherry trees.

So if I built a three or four foot high hugel mound in front of the tree, and maybe another behind them, would that delay flowering by keeping the roots cool and shaded? Not to speak of storing water and feeding the tree. Or would this just increase the temperature imbalance between the top and the bottom of the tree?

The easiest and least expensive way that I have found to deal with the problem of fruit trees flowering too early is to choose different varieties... Plant varieties that are known to flower later in the season, or that are known to be more frost tolerant.

My apricots flower about 10 days later than my next door neighbors. It makes a world of difference.

Hello Joseph,

That works for Apples, sour cherry, and Plums here. With the right varieties, they can generally doge the frosts. (Though not always. There is an orchard of heirloom, locally adapted apples right next door to my site, and the temperatures were in the eighties by the end of March one year. Then the temps dropped down to 15 in April. Everything bloomed and was frozen out.)

But peaches, apricots, and sweet cherry are always a gamble, even with the extension approved varieties.

I know you live in a similar high desert climate; do you have any variety suggestions?

Hi Gilbert:

We had the same unpredictable late frost issues when in the SW Idaho area (high desert like Colorado). Since we couldn't ever do anything about the frost weather and wanted a few particular early varieties in our home orchard that were sensitive to blossom freeze, we used Christmas lights. We had a huge box of the old style big colored glass lights for exterior use, like you would string on the outside of your house. Each spring we would wrap the sensitive trees in strings of lights and plug them in on those nights that had a frost warning. The heat from the large glass bulbs strung around the trees seemed to be enough to keep most of the blooms from freezing. We still lost some fruit on very cold nights but not the entire crop. This wouldn't be practical if you had a lot of trees to protect I suppose but for our handful of trees it worked great. Besides, it's festive looking to boot. Easter lights instead of Christmas lights!

I like the Christmas light idea! It is a community orchard, with maybe 20 trees that would need protection, and lots of help available, so it should work.

Sorry that I can't be of help regarding varieties to recommend. All of my trees were grown from seed.

I figure that getting fruit 4 years out of 5 is great odds. That's about what my walnut tree does. It flowers even earlier than the apricots, so once in a while the flowers get frozen.

The joke in Denver is that apricots are a nice tree - with fruit every ten years!

Maybe I should just start planting hundreds of pits and seeds, then. Something to think about.

the old standard advice was to plant on a north facing slope = they don't get as warm. That still sometimes didn't help, With the weather changes we've had all over the country this year I expect the fruit set this year will be poor in general. If some fruit sets it may grow extra big because all the strength goes into the few fruits.

What I've done is make a kinda shade scoop (opposite of sun scoop) with one of my hugel beds. I shaped my bed like a question mark with the open side facing North/North West. This protects the tree from the prevailing winds, but still sheds cold air down slope. The only direct sun the area around the roots gets right now is a couple hours around noon-ish. The scoop collected a ton of snow being on the leeward side, and while the soil in the mounds has consistently warmed to 40 degrees the mulch and soil around the root zone of the tree is still frozen (even a little snow in there still). I'm pretty optimistic that this will delay blooming until most danger of frost has passed. This is only my second season with this set up so I don't know yet. I do have another apricot planted on a swale about 20 yards away from this one, so I should have something to judge against to see if this experiment is working.

Hello Dave,

Great to see that somebody else is trying this!

We have the same problem here in North Georgia. It gets warm some days in March and everything starts to bloom out and then we have a killing freeze in March or April every year. So every year my plum trees starts out great and then gets the blooms or the plums frozen off of it. Interestingly my plum tree in my backyard is fine after the frost and the one in my front yard is all yellow and the leaves and plums are falling off. I covered both but with plastic. After it was already cold and dark I read that I should not be covered with plastic so I'll know better next year. I haven't been able to find any late blooming varieties it's very hard to find plum trees in my area at all. For years I've been trying to find cherry plum trees because my grandmother grew cherry plums when I was a small child in Jesup Georgia and they were fantastic. So I finally got a couple at tractor supply company and they're about 3 years old and have plums every year but I rarely get any edible ones by the time they are ripe due to birds squirrels deer and frost.

I've got some peaches that I planted behind a wall; they are still too young to bear, so we'll see in time.

Here in Western Illinois this seems to happen every year now.  We see several 70+ degree days by the end of March when frost is still inevitable in early to mid April.  We've been setting out a large industrial/garage fan facing our trees on the expected frost nights.  If the air is moving its more difficult for the frost to setup.  Seems to work just fine for lighter frosts. Although I know this isn't a feasible option for those in the dry western states, I would like to try including some burn barrels for heavier frost nights.