Is This Plant Really Hardy to Zone 4?

Those of us in northern climates always check the rated hardiness of plants we buy to make sure they can survive the cold winters. I live in a borderline area that is zone 4 to zone 5. I also live on top of a mountain which tends to cause about a two week delay between when plants bloom a couple miles down the road at the base of the mountain and when they bloom in our yard. All of which means I look for zone 4 hardiness whenever I add plants to the yard.

But just because a plant is rated for zone 4 doesn't mean that it is comfortable in zone 4 climates. Forsythia bushes, for example, grow very well in our yard and around much of New Hampshire without fear of being killed off by cold temperatures. A late frost or excessively cold spell during the winter, however, may mean that the forsythia will not produce any flowers, or very few, during a particular spring.

The same is true of many fruit trees that are supposed to be safe for zone 4. Some peach trees, plum trees, and other varieties may suffer from the same late frost damage that forsythias may experience. If this happens, they may have no blossoms at all in a given year, and, therefore, no fruit at all in the fall.

If you have fruit trees that produce fruit some years and none in others, it may be a result of the tree being planted in a zone that pushes the limits of it cold tolerance. The tree generally isn't hurt by the late frost or winter cold snap, so technically it is hardy for the region, it's just that it may be unable to produce fruit or flowers unless the winter weather has been particularly favorable.

This year turned out to be one of those years for us. We have loads of developing apples and grapes, but the forsythia, peaches and plums never blossomed at all. Their tender flower buds having been nipped by Jack Frost. Covering them with a thin, light tarp or plastic sheet would probably have helped if we could have predicted the coldest weather or the rogue late freeze. Such covers help trap ground heat and form a protective temperature barrier around the covered plant and will also prevent frost from precipitating directly on the plant.

If you do elect to cover them, just be aware that the covers can also catch snow and become far too heavy for the plant to support. This can cause broken branches or even snapped trunks completely destroying the young fruit tree.

Choosing plants that are hardy to one zone beyond where you live will help ensure that they produce regularly. If you must have peach trees or other semi-hardy fruit trees in New Hampshire or other northern climes, choose a hardy variety, such as the Reliance Peach, and understand that unless you take precautions to protect them, you may have some years of little or no fruit production.

Free landscaping stock, transplanting

One of the best things about growing plants that are native to and very hardy in the area where you live is that they tend to reproduce. This gives you free landscape stock to use elsewhere on your property. A short list of cold-hardy perennials, shrubs, and trees for northern climates can be found here.

I just finished digging up three brand new forsythia bushes from around the one big one that we had in our yard. Forsythias reproduce mainly by a form of self cloning. The tips of the long braches that extend out along the plant's perimeter will eventually droop down to the ground and take root. In just one year of growth after these new rots begin to take hold, new shoots as much as two to three feet tall will mark a new plant that can be separated from the parent plant and transplanted.

Simple Tips for Eco-Friendly Landscaping

Our big forsythia has a diameter of perhaps twenty feet from branch tip to branch tip. Around its perimeter are perhaps 15 small plants. Each one is made up of many individual shoots coming out of the ground from a common root ball. When you dig them up, you should keep the clusters together to avoid damaging the roots too much trying to separate them. This will also help the young plants to look fuller and more colorful while they are still small.

The proper time to transplant varies by the type of plant. Generally, I like to do it in the spring. The ground is moist and not likely to dry out or require too much extra watering and many plants here in New England are already in the "re-establishing mode." That means they are actively sending out new feeder roots to fuel the development of new spring leaves and flowers as well as the year's new growth. If you dig them up without damaging too many of the roots that have laready begun growing, you can take advantage of this spring activity and the transplants can get off to a strong start in their new locations. Depending upon the plant species, this may differ a bit from conventional advice, but it works well for me as long as I provide the TLC needed after transplanting.

As with any newly transplanted landscape stock, keep a close eye on it for a few weeks to make sure it stays healthy. If roots are damaged or if, as with a forsythis you have to cut around a root ball to keep it manageable, you need to watch for signs that the plant isn't getting enough water through its remaining root system. If it starts wilting or loosing leaves, that's a sure sign of dehydration and the plant should be thoroughly watered until it no longer wilts between waterings.

As eco-friendly gardners, using collected rainwater for this purpose is a good idea, especially for those who live in areas where clean water sources are overtaxed by increasing human demand.

OK, now I'm off to separate some irises that have multiplied to the point of overcrowding.

Happy Gardening!