Well paper birch shoud certainly be hardy enough for your area. Produces a quite large specimen, however, unless site conditions are stunting in some way.

Yes, paper birch. Far and away the most resistant to BBB. BTW, those purple-leaved hybrid cultivars seem to be borer magnets, at least in my experience.

+oM

True paper birch (Betula papyrifera) does much better here in zone 5 (our summers are a touch warm for paper birch) than European white birch. The reputation of birches as being high-maintenance, pest-prone trees stems from Betula pendula.

Could you expound a bit on your location? Zone 4 in Minnesota is different from Zone 4 in New York, which is different from Zone 4 in Michigan, and so forth.

you would start by finding out if birch borer is an issue in your area ..

if so.. then you would research borer resistant varieties... and note the key word there is resistant.. not borer PROOF ...

and then you would buy a tree .... treat it anyway with a systemic .. to insure you start with one that doesnt have borers ...

birch is not a great tree to garden under.. so if you have any inclinations that way.. you might want to look at other options ...

good luck

ken

The big two factors with placement of Betula papyrifera are: Full, or nearly full sun, and a soil that doesn't dry out too much. Given those two things, paper birch can be wonderful trees. Of course, this is easy for me to say given that I live in the land of birch. But I know lots of foresters, most of whom migrated up here from Illinois for some reason, who never miss the opportunity to slam birch. One guy, a fully degreed individual, even stated that "birch doesn't grow in the woods around here". Must say, that was news to me!

+oM

What Ken said...."birch is not a great tree to garden under.. so if you have any inclinations that way.. you might want to look at other options"

Shallow surface roots make it hard to dig in and steal resources from the garden plants under them.

Thanks so much everyone. Do the roots interfere with with lawns? Do they cause surface problems for mowing grass lawns? I am south facing with a great deal of sun... I need open shade as it is lawn approx. 30'X 30'.. so I suppose a tree that is mid sized would be appropriate. Any ideas please? Thanks in advance!

Toronto? You should be fine. You're within the native range of paper birch. Like +oM said, plenty of moisture and sunshine is key with paper birch.

Hiccups4, probably the best route to a favorable rooting environment for paper birch, should you elect to plant one, is a wide mulch ring. This will provide a cooler root zone, a better moisture status month in and month out, and while slowly decomposing, enrich the soil in just the manner woodland trees like. It will also keep you from having to mow right under it for some time. Other herbaceous plants can be grown in that mulched area, but keeping turf out will give great benefits to the young tree.

BTW, now that I realize you're in Toronto, I'll mention the other really good birch for your area-yellow birch-Betula alleghaniensis. Not often seen in the landscape setting, they nevertheless can make really fine specimens in the yard, provided you are in a favored area for them, and you are. Just thought I'd mention, should you wish to go with a somewhat less often seen species.

+oM

Betula platyphylla 'Fargo' is touted as heat, drought and borer resistant.

Probably not going to meet your shade goals though...