Micro Management

As much as I love cold weather, I have to concede that we experienced way too much of a good thing this past winter.

Long periods of extremely cold weather are the norm in many other parts of the country, and plants survive. Here, however, our local plants may be accustomed to surviving the isolated sub-freezing night, but sustained, frosty temperatures lasting nearly a week are something they weren’t meant to handle.

I’m sure you’ve seen the results of our cold snap in the news: Much of the state’s citrus population – yes, coincidentally, the wonderful treats I wrote about in last month’s column – has sustained long-term damage and the trees in many cases will take two years and more to recover. And that doesn’t just affect us here: The rippling effects will be felt in

grocery stores nationwide for the foreseeable future.

As a homeowner, I’m always aware of what freezes can do to my garden, but I recognize that it’s primarily a visual blow and that whatever falls prey to the weather can be replanted. As a landscape designer, however, the scope of my concern is larger as I consider my clients’ losses and reflect on a key lesson to be learned: As professionals, we must be keenly aware of the climate and how it might be reflected in our clients’ yards.

The lesson is about more than the climate at large: In this recent cold snap, I couldn’t help observing how topography and the presence of architecture played into the ability of plants to survive the cold.

CULTURAL AWARENESS

I had yet to finish harvesting my Satsuma tangerines a few weeks back when I saw the weather forecast on the nightly news and heard that we were in for several nights of sub-freezing temperatures.

I went to sleep each night fearing that what was left of my crop would succumb to the cold, but when I walked into my yard each day, I was surprised to find not only that the fruit had survived, but that it hadn’t sustained any of the damage that was already being reported by citrus growers throughout the state.

My garden had experienced subfreezing temperatures each night for a week – temperatures that had my neighbor’s garden sporting icicles all over the place because an automatic sprinkler valve had stuck in the “on” position for a full day. In my own garden, only a few yards away, there was no serious damage, although there were some distinct but disparate consequences.

One morning, for example, I was pleased to note that a plant directly adjacent to the house appeared perfectly normal – and disappointed to see, just five feet away, the same variety of plant completely devastated by the freeze.

Armed with this observation, I took inventory throughout my garden, front and back, and observed variations on this same phenomenon in different locations throughout: Some plants had apparently survived because of their proximity to the house or some other substantial structure, but other perennials of similar type just a few feet away (but out in the open) had not survived.

This immediately carried me back to college science classes and discussions of microclimates. I’m no expert on the subject, but I clearly recall that any structure that gives off heat – particularly heated spaces such as homes but also walls and other sources of radiant heat – can warm an area up to a foot or two away enough to protect tender plants from freezing temperatures.

Everywhere I looked, this concept applied: In at least three locations, for example, Plectranthus ‘Mona Lavender’ had survived up against the house, but it has sustained frost damage in all other locations, necessitating severe cutting back.

But this tour of my yard didn’t resolve the mystery of why my fruit trees had made it when so many had not.

GRAND-SCALE ISSUES

Why had my Satsuma tangerines and other citrus survived the bitter cold while growers throughout the region incurred heavy losses? The answer, it seems, is all about location, location, location.

In this case, my home is situated on an upslope, and much of the reported damage to citrus crops apparently occurred in low-lying areas. The difference is no more than a hundred feet or two, but being up at this slightly higher elevation seems to have protected my trees from the worst of the weather’s effects.

The difference: Cold air pools in low-lying areas such as valley floors. Up on a slope at any sort of elevation above that floor, such pooling doesn’t readily occur. In addition, the air kept moving, and stillness apparently enhances the damage subfreezing temperatures can do.

I’m sure I don’t have all the answers (and I’d love to hear from anyone who is better informed, because I am truly curious), but what I’ve observed in the weeks since the big freeze has made me want to know more about microclimates and how I can use them in my design work to enable more plants to make it through harsh weather.

The implications here are wide-ranging. Placing the same plant throughout a client’s garden, for example, may make for a cohesive design, but I will never be able to guarantee it will perform equally well in all locations. (I wish I had a dollar for every complaint I’ve heard from clients who think I’ve sold them a bad plant because others of that same variety are doing just fine: I’d be rich!)

Although the weather is a key factor here, there are others that come into play to influence the success or failure of a planting scheme:

[ ] Soil composition. Using multiple plants of the same variety in various places around the same yard is no guarantor of success, mainly because the quality of the soil will vary from spot to spot around the yard. Any sort of amending, whether with fertilizers and composts or with natural decomposition of fallen leaves and other debris, will serve a local role in how plants perform.

I’ve taken a soil sample in one spot and found soil of a completely different composition just a few feet away – a particularly common phenomenon in developments where the terrain was significantly disturbed during construction. Plants will respond in different ways in each situation, depending upon the health of the plant, its type and its general characteristics (not to mention the unique nature of each specimen).

[ ] Access to Water. Let’s face it: No matter how good an irrigation system is, it’s virtually impossible to get the same amount of water to each plant in each location and we all do the best we can given what we have.

There are too many variables at work here for this ever to become truly predictable. I’m not suggesting that we give up trying; instead, what I’m getting at is that we must recognize the imperfections of irrigation systems, do what we can to anticipate the needs of specific plants and then take the time to follow through and make sure that what we leave behind has the greatest possible chance of success.

In all of this, in fact, I’m not advocating that we concede. What I am suggesting is that we need to take a holistic approach and be more selective about where we place plants within a design, try to amend the soil locally so that it provides the best possible cultural environment for the root system of each plant and design irrigation systems to support the plants’ long-term needs as effectively as possible.

IN THE LOOP

What I’ve presented here is, of course, a very personal response to the vagaries of our recent winter here, so forgive me if what I’ve described is something your local climates and microclimates force you to consider on an ongoing basis. Chalk it up to the ability of events like these to focus our thinking: There’s no harm to be done in giving clear thought to what we do!

I know in all of this that I will never be able to guarantee that a given plant will survive in a given location, but that I can support each one in ways that give each plant the best possible chance of thriving within the microenvironments present on the sites we touch. It’s impossible to anticipate everything, but applying an all-encompassing approach will surely give the plants we select and place a better shot.

As always, the key here is communication with your clients about their expectations. The fact that a plant dies does not mean you sold anyone a bad plant.

Many (if not most) of us offer guarantees on plants for specified time periods, qualified by clients’ provision of appropriate maintenance and care and their early communication when something happens (such as a sprinkler problem) – all dedicated to assuring the best possible outcome for their projects. Just the same, clients need to understand that plant demise is normal in lots of situations. (Most contractors I’ve worked with tell me that it’s normal to lose up to 10 percent of a planting within the first year, although I’ve never witnessed devastation that widespread and have experienced only insignificant losses through the years.)

As I see it, there’s no harm in preparing clients ahead of time and letting them know that differences in temperatures, soil conditions and watering will all influence the success of their plantings. This positions them to be both watchful and supportive and gives them distinct roles in assuring long-term success.

This won’t help when winter wreaks havoc, but at the very least it will knock the edge off your first conversation once the damage is assessed.

Stephanie Rose wrote her Natural Companions column for WaterShapes for eight years and also served as editor of LandShapes magazine. She may be reached at [email protected].