why can't a zone 8 tree live in zone 9. I bought a kousa dogwood that was delivered but never grew,or thrivedi

Question

it was a bareroot. we had temperatures inside the zone 8 requirements.

Answer 1

There is not only a cold hardiness zone, but there is also a heat hardiness zone. It could have had a fungal or a viral infection when it arrived, it may have been shocked by the shipping and the replanting. The coating on the bareroots may have not been thorough enough and may have allowed it to dry out. Was it dormant when it arrived? All the guessing in the world right now will merely suggest possibilities. If it was guaranteed, I would contact the seller, and the very least that they should do is replace the tree.

Answer 2

USDA Zones refer only to cold hardiness requirements. There may have been other reasons that the tree didn't thrive, such as soil composition, available light, planting regimen, and wind conditions.

Kousa Dogwoods should be hardy to Zone 5, so I don't know why there was a problem with that. There may have been a problem with too much heat &/or sunlight, as they tend not to like hot, dry conditions. Your tree could have also been mislabeled. They are sometimes mistaken for Cornus florida or other species of Cornus which have some intolerance for diseases.

Answer 3

Those zones aren't only about temperature extremes; they also indicate the length of the growing season. If you don't have warm enough temps for a long enough period of time or dormant temps for a long enough hibernation period, the plants just will not grow.

Where did you get the plant? I've always relied on a local nursery rather than buying from big-box stores, their employees actually know what they're doing and will give you much better advise.

Answer 4

I am not sure what the zones you mention are, but I get the concept. When I moved from the mid-west (US) to the southwest I kept trying to buy my favorite flower (cut or plant.) Cut flowers had to be special orders and cost me $5 a stem. The company I tried to get plants from refused to fill my order until I signed a waver acknowledging I understood that they would not grow where I lived. I did manage to force bloom 3 sickly looking stems of "lily of the valley" from the plant which grew like weeds on the Midwest. Then I took their advice and gave up trying.
So, it is climate, soil, sunlight, and temperature as well as water availability. What thrives in one set of conditions struggles to survive in others.

Answer 5

I think one part of the plants' needs is left out-- frequently. Dogwoods in general are "understory" trees-- meaning they want sunlight but not lots of it-- so, you'll see dogwoods living under pine trees-- trees that let light through. If there are dogwoods where you live now-drive around and see their environment. Also- check with the local grower-- and see what is the trick in that part of the world.
good luck

Answer 6

I guess that is why they classify them into different zones...zone 8 and zone 9 are seperated as different zones for a reason.