It really depends on your location and your local weather.

I typically wait until cool weather, about mid-September in our area, to transplant trees. Usually we get more rain and cloudy days in September and early October and moderate temps and increased moisture helps the transplanted tree to become established.

You should allow the tree 6 to 8 weeks before the ground freezes up for root growth. Make sure your new planting hole is the same depth as the original hole but about twice as wide. If you have compacted soil it may help to rough up the edges of the planting hole with an axe or similar tool, making it easier for the roots to penetrate the surrounding soil.

Once transplanted, make sure the tree is watered properly. You need to have sufficient water available to the roots to hydrate the tree, but you don't want roots standing in water. If you have compacted or clay soil you wont want to water as often. If your soil drains quickly you may have to water more often. You'll have to judge that yourself.

You should also apply mulch around the tree. About 2 to 3 inches deep of coarse pine bark around the tree should work. Mulch retains moisture in the soil and helps moderate ground temperature while also limiting weeds. Mulching is very important and can greatly increase the chances of the tree's survival. You should extend the mulch beyond the drip line of the tree but make sure the mulch is not in direct contact with the trunk of the tree.

BTW, when transplanting try to keep as much of the rootball intact as possible. The more roots the tree loses in transplanting the harder it is for the tree to re-establish itself in the new location.

HTH,

Dave

good advice above ..

its more of a gut feeling, rather than a calender thing ...

the key is COOL NIGHTS .... in my z5 ... i can GET AWAY with as early as mid-sept ... IF THERE ARE COOL NIGHTS ... and more of such are forecast ... and i can go through about the third week of Oct .... and a bit later if there is some transplanting emergency .... like i forgot one.. lol ..

you can probably move those dates up a week or two ... in z3.. but that is SPECULATING on my part .... the local Ag office or Forestry office.. soil conservation... can probably give you something more precise for your area ...

a perfect scenario would be 60 to70 degree days.. with nights in the 50's ... warm enough soil temps to encourage roots to continue to grow .... but cool enough at night.. for the plant to pump enough water for full recovery ...

even if it gets to 80 ish during they day.. the cool nights allow recovery ...

BTW... how big are your spruce???

good luck

ken

Hmm. The temps mentioned don't help much. A typical summer day here will get into the mid 70's. 50 is a common night time temp. Sometimes we get a 'heat wave' where the temps get into the upper 80's for a week, and there is a run on fans at the the box stores.

Comparisons:
We traditionally put out bedding plants on the May long weekend which in Canada is the third Sunday in May. This year we had killing frosts until June.

We have had snow in August, but that is a fluke. But 2 inches of non-sticking snow in September happens every few years.

The poplar change colour typically in mid September. And 15 September is the average panic-day-the-garden-is-going-to-freeze.

HOWEVER, going through my photo library.
2004: 4" of snow on the ground by 22 October.
2008: Leaves starting to change by 10 September, then we had a very long Indian summer. I was watering until November, it got very cold for a week, then I had to fire up the irrigation system one more time in December.

On the average first snowfall that sticks is early November. Typically the pond freezes over a couple weeks later than that. But we have had -10F temperatures for Halloween.

Generally all our conifers are finished with active growth by early August. Needles may get fuller, but they won't grow.

To Ken: The trees I want to move are 4-6 feet tall. I moved about 150 this spring, selling most of them and planting the ones where the root ball fell apart on my own farm. Of those 15, 13 survived and are nicely green, although as I expected they didn't grow much. (Busy putting out roots.) My followups on the ones I sold say that they have done well. (I offer replacement if any fail.)

I dig by hand. A 4' tree gets a 16" root disk. About 30-40 lbs. A 6' tree gets a 20" disk -- about 80 lbs. (Spruce don't seem to have roots deeper than about 4-5 inches.)

My rule for spring is that I can start digging when the ground thaws, and I stop when the buds are beginning to swell, and that they should be in the ground in their new home by the time the papers start to fall off the tips.

I'm trying to come up with a set of guidelines for fall. At this point my best guess for balance is to start digging after the first killing frost, and to have them in the ground by the 2nd weekend in October. That will typically give them 3-4 weeks of warm days (60's) cool nights (30's)
Ground, especially if I mulch, won't freeze until November.

Follow that up with a liberal application of snow with the snowblower?

Sometimes we get a 'heat wave' where the temps get into the upper 80's for a week,

===========

that is the week to avoid ... lol ...

i bet you could start as early as 9/1

is there no local county/provincial agency .. in CA... that you could contact with such an issue???

sounds like you know what you are doing....

my only concern.. is your thinking that 3 to 4 weeks is OK ... probably is.. but 6 to 8 would be better ...

i try to be done by 10/15 ... with ground freeze around 1/1 .. so i am getting 60 to 75 days [2.5 months of potential root growth] .. on the presumption that a foot down.. root growth will continue until the soil freezes ...

frankly... having no experience in z3 ... IT SOUNDS TO ME.. that you can do it all but that one week when they sell the fans.. lol ...

good luck

ken

Oh my! Our "lows" have been higher than some of yal's "highs".

Good one jute, you were the right one to chime in. hahahahaha!

Sherwood,

You know what's up. With temps that you have in your climate, you could easily move conifers/deciduous anytime except between bud break and till mid-summer. The grafting season for summertime is when you could start for your area. I typically think of zones as splitting apart two weeks for each one lower or higher. Pin Oaks are the tree in Spring when their leaves have fully expanded to predict no more frost. That's an old farmer's almanac precise recorded event. Transplanting for us folks with warmer summer climates also as you mention with your Poplar tree information is when any of the leaves of any of the trees start to change and anywhere a week or two before this as we watch the weather drastically become cooler. That's us though.

During grafting at summer time the plants are now building their root-systems, once-again, like spring building. As long as you water, I see no reason with the temps you guys have to move anything. Japanese Maple grafting starts here mid-june thru the end of August.

My final though is for you to move half of them nowish and the other half when your gut is saying that the temps are beginning to plunge or a trending of fall weather is, occurring. Use your straw, keep them happily moist and compare the root-systems, next year.

Take care,

Dax
p.s. good advice as usual Ken....