When to ground plant saplings?

[LooselyWired]

I have a couple of Amur maple saplings about 18” high in 2.25” nursery pots + a sargent crabapple & a sieboldi crabapple also in 2.25” pots. I want to ground plant them all. We are now in the midst of summer heat in zone 5 (though it hasn’t been bad this year). To give them the best chance, is it better to get them in the ground around September 1st, or should I overwinter them and plant them next spring? If I do overwinter them can they stay in those flimsy little plastic pots, or should I slip them into something a little more substantial?

 

[rockm]

I'd be cautious about ground planting amur. It is an invasive species. If you're planning on letting them grow for a while, there's a chance they will colonize. Sale and importation of the species by nurseries has been banned in some states. Both the crabapples and amur will be fine planted out in a more substantial container for the winter, provided you give them a bit of shelter from the wind.

The article from the Minnesota Dept. of Ag. is worth reading through for control and how it spreads
"Amur maple has been found to produce allelopathic chemicals. It can alter habitats, invading prairies, grasslands, or open woodlands and adding a shrub layer."

Amur Maple | Minnesota Department of Agriculture

Common Name: Amur Maple

www.mda.state.mn.us

 

[LooselyWired]

Thanks for the reply. I know that amurs are considered invasive, but I didn’t know about the allelopathic chemicals. I really don’t want to stunt or slow development of nearby trees or landscaping. And although they would be in a location where I can easily eliminate unwanted sprouts in my own yard, I really don’t want to be responsible for spreading them across the neighborhood. Perhaps, I should keep those bad boys potted?

I only selected Amur maples for one reason. They are a lot more cold hardy for sticking in the ground here than tridents. should I look at some other types of maples. Field maple?

 

[Shibui]

There's no problem planting any tree in the ground in summer. They will mostly take off and grow.
However you do need to think about what you want to achieve:
A big landscape tree - no problem
A potential bonsai - not quite so simple. Good nebari is an important feature on many bonsai, especially deciduous. Container grown trees are notorious for having tangled and circling roots. Trunk is not the only part that thickens fast when growing in the ground. Roots do too and if the existing roots are tangled they will still be tangled but much thicker after a year or 2 in the ground. Usually the result is a swollen, lumpy mess.

If you are certain that the root system is well spread and radial there's no problem planting out but if there's any doubt I would strongly recommend waiting until spring root pruning time to sort out roots first.

 

[BobbyLane]

Would add that if you do plant them over summer, water them in for the first two weeks or more. Will be a few weeks before they adapt. Ive planted trees during summer many times, sometimes just to create more space.

 

[LooselyWired]

If I do plant them now, do you think they would tolerate lifting them & addressing the roots in the Spring?

I’m also wondering if I decide to overwinter them and plant them in the Spring instead about the media. Right now they are all in bark & vermiculite. Would getting them into something less water retentive before winter be a good idea? I do have a detached garage to keep them out of the wind if needed, but it remains below freezing for most of the winter even inside. I know Amur Maple & Crabapples are tough species that generally don’t need any particular winter protection here. I’m just wondering if leaving them in something loose and water retentive changes that? I also assume, perhaps incorrectly, that the bark/vermiculite may break down faster in winter.

 

[Shibui]

No problem planting now and then lifting in spring in my experience. You probably won't get much growth between now and end of growing season but the trees should be easier to manage.
I don't have sub freezing winters so not sure if that would deteriorate the soil mix but I doubt it.
You will need to get overwintering suggestions from those who have similar conditions but I see lots of talk about burying pots of cold tolerant species for winter. Planting these in the ground should provide similar protection.

 

[rockm]

Thanks for the reply. I know that amurs are considered invasive, but I didn’t know about the allelopathic chemicals. I really don’t want to stunt or slow development of nearby trees or landscaping. And although they would be in a location where I can easily eliminate unwanted sprouts in my own yard, I really don’t want to be responsible for spreading them across the neighborhood. Perhaps, I should keep those bad boys potted?

I only selected Amur maples for one reason. They are a lot more cold hardy for sticking in the ground here than tridents. should I look at some other types of maples. Field maple?

The amurs will likely not become a problem for a few years in-ground for other trees, but if left alone, it will become an issue.

FWIW, unless you are in Zone 3 or lower, neither the crabapples or the Amur will require much (if any) protection in winter--it's hard to gauge since you don't provide any info on your location other than "midwest" which is an area larger than Europe... and has many USDA Zones running through it.

 

[LooselyWired]

Trees are parked in USDA zone 5a for the most part. Much of my time is split between central Illinois, central Iowa, & northern Missouri. Depending on the season & which women aren’t mad at the time.

 

[LooselyWired]

Thank you all for the replies. Much appreciated

 

[AJL]

Amur maple would only become a problem and spread if it set seed ,which is highly unlikely in such young plants. No reason why you shouldnt ground grow for a short period to boost their growth and fatten them up then pot up when they have grown enough.