People often ask, “What can I do to protect my plants over the winter?” I’ll try to keep this shorter than War and Peace, but there are so many factors to consider relative to safeguarding plants in the landscape. Let’s start with the single most fundamental issue: plant selection. When choosing plants, be mindful of hardiness. This is somewhat of a moving target as we get warmer and additional plants are added to our palette. Conversely, we lose plants we used in the past as certain plants cannot tolerate heat. It is always my goal to offer the best information I can (mistakes are made occasionally) and keep things somewhat simple, while not insulting anyone’s knowledge. I will make the assumption that some may not understand hardiness zones, so I’ll take a minute to explain. The country is delineated by cold tolerance. These zones are driven by what is considered to be the maximum low temperature for an area. Here in Chester we are typically considered a zone 6b (minimum temps from -5 F to 0 F). I believe we are in between 6a and 6b, with b being 5 degrees cooler than a. When seeking out plants for your landscape, be mindful of the hardiness. Admittedly, there are always exceptions—and our risk tolerance—in trying plants that may be listed as warmer zones. Recently I brought in Clerodendrum trichotomum, which is certainly listed as a zone 7. Interestingly, there are areas in Morris (mostly east) that fall into a 7. Oftentimes it is our experiences that determine what plants we might roll the dice on. There is a Clerodendrum growing in Ringwood at Skylands State Park that has been there for years. One of my employees lives in the vicinity and has one in his yard that is thriving. Conversely, you might find you have issues with a zone 5 or 6 plant for other reasons. Exception/rule. When we gamble here, we try as best as possible to educate our customers as to the risks with certain plants. In the case of the Glorybower, I knew the plant, brought in five—not intending to sell any of them—but rather reward some of my fellow plant geeks with a somewhat unusual woody plant. TBD.

So we know we’ve chosen plants hardy for our climate. How they are placed in the landscape is another major factor. Generally speaking, try to avoid south/southwest exposures for broadleaf evergreens. These include skip and Otto laurel, azalea, andromeda, rhododendron, and holly, to name a few. Why? Even though our landscapes hibernate in the winter, it does not mean mechanical damage cannot happen due to physiological processes (about as technical as I’ll get). Most broadleaves have a wider leaf surface that is quite effective at catching the sun’s rays. When temps approach 25 degrees or lower for a consistent period, the ground obviously will freeze. No moisture can be taken up by the plant through the roots. However, on a 15-degree day (arbitrary) with the sun shining, plants can lose moisture through foliage with no ability to replace it. The leaf surface on a cold, sunny winter day can heat up enough for the process to start. This certainly can cause damage to a plant, which in most instances will not be seen until plants begin to wake up. You see this oftentimes with holly, which looks good all winter. When we consistently reach temps between 65–70 degrees or higher, we tend to see damage show itself. My greatest point here is that much of this can be avoided by utilizing the right plant to begin with. You can shelter broadleaves or temperamental woody plants by wrapping them with burlap or applying an anti-desiccant such as Wilt-Pruf or Vapor Guard. These products provide a film-like barrier that can help prevent moisture loss. It is important to remember that frequent snow and rain events will degrade this barrier, and so they will need to be reapplied. Personally, I have a serious issue with physical barriers such as burlap for protection. I am not one who wants to look at burlap in my yard for three-plus months. Better to use the proper plant and skip the burlap. There are occasions for newly installed plants when a temporary shield for one or two years to help get the plant established, I feel, would be acceptable. Obviously a personal choice. Oftentimes the key is getting a plant established, thus the one- or two-year shield. Once established, many plants can tolerate more extreme conditions, as they should have a fairly vigorous root system to help stave off the ravages of winter.

I mentioned broadleaves as a potential winter issue, but this does not mean narrow-leaf conifers don’t have winter hardiness issues. I have been told by multiple growers that plants such as Green Giant arborvitae and Cryptomeria japonica tend to continue growing well into November. This can be a serious issue as early cold fronts come through (feel like I should be standing in front of a weather map pointing) and will damage tender new growth. What you might encounter on Green Giant or cryptomeria are dieback issues from the top of the plant. Even our significant conifers located in a windy environment and newly planted can suffer damage—again from moisture loss. Pivoting to deciduous: some of you might have experience with dieback from the top on hornbeam (Carpinus). This is almost always a result of winter damage. I hear so many say, “I’m not using hornbeam anymore.” How about we practice proper procedures? Probably best to refrain from planting certain plants, such as Carpinus, too late into the fall. What is that time? On certain plants I would not go later than late September–mid October. The earlier you plant prior to winter, the greater the ability for a plant to send out roots.

“I didn’t know I had to water.” Too many times. Simply because a plant is shutting down up top where we can see it, it could very well still be active, translocating moisture through the trunks/stems (sorry, had to justify the college education). Irrigation prior to winter is one of the single most important issues facing our newly planted landscapes. Most of you might not know that almost every load of B&B nursery stock that arrives here gets hand-watered as it comes off the truck. We feel this is critical. Take a ride through Plant Detectives even now and you will find people watering nursery stock. Point being: for as long as reasonably possible, new plantings should be watered going into the winter. Be mindful of natural rainfall and temper as needed.

I have skirted the obvious: a good layer of mulch to protect the roots, hold moisture in, and—to a small extent—minimize soil temp fluctuations. I have referenced anti-desiccants, which truly can help if applied properly and regularly. Since I referenced temp fluctuations in the soil, it is important to understand that a good deal of damage occurs due to temperature fluctuation in the air. Be mindful of the January day that starts out at 50 degrees but plummets to 15 degrees. Here is where so often damage occurs. There is also a window for most plants relative to pruning. Typically, in late July (this is a very broad stroke), it is advisable to hold off on pruning. Most often when you prune a plant, you encourage new growth. Pruning too late will ensure that new growth succumbs to early freezes. When in doubt, wait until a plant entirely shuts down. It is reasonable to think mid October on would be fairly safe. Be mindful of fall hazard-dig plants. We try as best as possible to avoid having plants dug that don’t appreciate being taken from their home in the fall—dogwoods, cherries, and Cercis, to name a few. We often opt to bring some fall hazard plants in container-grown to eliminate the fall dig issue. I then have to hear from the purists that they’ll never plant a container tree. I believe in container trees when planted and cared for properly and simply say, to each their own. In my opinion, if I cannot get a redbud in a container, I simply will tell the customer we cannot get field-grown until the spring. As an aside, I almost expect some maven to challenge me on some or all information I put out there. I suppose it makes folks feel better about themselves. Simply stated, my education and experience drive what I believe. I believe in the information I pass on. Some is knowledge-based opinion, some experience; however, I am quite comfortable with those who disagree. We try as best we can to accommodate all walks.

Keep planting and stay warm and healthy.

Cheers,

Art