Following a long, cold, and snowy winter, spring has arrived. The grass and trees are green again, but there is still evidence of damage to plants from the harsh winter. Among the plants particularly hard hit were Roses and Rhododendrons.
The explanation being offered in the local media on the cause of damage to these plants is that it was a dry winter. This may be somewhat true, however given that deep snow cover in much of January and February followed an alternately very rainy and very snowy December, there may be other factors at play. Another possible explanation may be related to the source of the nursery stock now growing in your garden and the prolonged very cold temperatures experienced this past winter.
Many plants available through major retail outlets may be sourced from southern nurseries. Even though the plants may be the same species as our own native specimens, local populations of plants adapt over time to the local climate. The degree to which this local variation happens varies among species, but when native stock is available, it is usually the preferable alternative.
For example a species found in our native forest may be able to tolerate temperatures to 15 below zero, while an example of the same species from southern stock may be damaged by somewhat warmer temperatures.
Since the past few winters have not featured exceptionally cold temperatures, many plants that are not normally able to survive the winter have been able to persist. In our yard a Rosemary bush planted in a sunny sheltered location during the 2000 growing season finally succumbed this past winter. Rosemary can survive temperatures down to around +10 and is therefore not considered to be a perennial this far north, however you may have other plantings which are considered hardy that may be in jeopardy if the temperature falls much below zero.
The best bet is to stick with plants that grow natively in similar environments near your home and whenever possible to use plants propagated from local stock.
For Long Island, an excellent resource, "Long Island Native Plants for Landscaping" was authored by Karen Blumer and published in 1990. This book appears to be out of print, but well worth the read if you can find it at the library. It gives details about a good number of native plants suitable for landscaping and identifies retail and wholesale nurseries that carried plants raised from local stock at the time. Many of the nurseries still exist and should be able to answer your questions about the source of their plants.
Aside from influences of cold and drought, evidence of winter plant damage from more obvious causes is not difficult to find. The curbside juniper shown on the left was damaged by road salt.
Much of the damage will heal over; even some of the "dead" branches on the Rhododendrons are showing a new bud or two. Therefore, if you've suffered winter damage to your plantings, showing a little patience might be best in the end. Of more immediate concern now are springtime pests, most of which also produce only transitory, if unsightly damage. See the "Seasons" selection for more on the current spring inchworm infestation as well as a few other pests.