Have the growing zones in Minnesota changed?

My short answer is no.

Sometime this past January when we were in the middle of a warm spell, the USDA revised its growing zones for the Twin Cities and labeled it zone five. There had not been a winter in 10 years with temperatures lower than -20 degrees F, the cut-off point for zone five. Of course no one could predict that a month later we would bust right through that temperature.

There is a surprise waiting for a lot of gardeners this spring: dead perennials. Garden centers have been carrying zone five plants for a few years now and with the national “okay” they will be everywhere in the next few weeks. Everyone seems to have forgotten that we had a zone four winter.

Storing peaches and cherries in the garage this year reminded me of two things: 1. the trees would not have made it though the winter unprotected and 2. We had solid freeze in early April following a week or more of 70 degree temperatures in March. Those wild March temperatures woke up my Nankin cherry bushes (Prunus tomentosa) which I did have planted in the ground. I had to cover the 4 foot bushes with layers of bubble wrap and a garbage bucket on top to allow the flowers to survive the dip into 15 degrees (flowers are usually killed around 28 degrees for most fruit trees.) It worked, but I wouldn’t have stood the chance of that kind of protection with a tree: good luck covering one.

So this spring or fall, when the garden centers try to temp you with cherry and plum trees, remember that they probably won’t make it without a protection plan, regardless of what the salesperson says. We are in Minnesota, after all, and averages don’t mean anything – temperature extremes may be just a month away.

see previous post
Getting into the zone