Steven A. Frowine - Gardening Basics For Dummies

Dry conditions: A very dry winter can also cause a lot of damage and even plant death for evergreen plants that continue to use and lose water during the winter. These plants should be watered when the ground isn’t frozen, if needed. Sometimes it’s winter drought, rather than winter cold, that kills a garden plant.

Winds: Drying winds can be very damaging. Some gardeners provide windbreaks to relieve this problem.

Varmints: Don’t forget varmints, especially voles and mice that can do invisible underground root, stem, and bulb damage that occurs most in the winter when less of their natural food is around.

Climatological data comes from the horticulture industry, university researchers, botanic gardens, and so forth. Sometimes when a new plant enters commerce, the zone rating is conservative and after a while — with more people growing the plant in different areas and with more research — they find the plant to be more or less cold-tolerant than they originally thought.

Whether a plant can survive the winter isn’t your only concern. You know annuals are going to live for only one season, but you also want to know how long that season will be. After all, you may not be pleased if your dahlias die before flowering or your tomato plants freeze before producing much fruit. Unfortunately, hardiness zones don’t tell you much about the length of the growing season. Enter the frost zone map.

Zones are determined not only by temperatures but also by the climate, which combines temperature readings, rainfall, humidity, wind, air pressure, and other factors. Climates in frost zone maps are generally determined by growing season, the time during which — hold onto your hats — plants add new growth. The last spring frost and the first fall frost bookend the growing season, marking a nice period of frost-free days. Basically, this time period is your window of opportunity to plant and nurture and enjoy your home landscape, whether you’re growing flowers or edibles. Make the most of it!

In really mild areas, such as parts of Southern California, Florida, and the Gulf Coast, the entire year is likely to be frost-free and wide open. The rest of us may feel we’re not as lucky (but just remember that those folks, and their plants, have to contend with intense summer heat and humidity, not to mention bugs that are never killed by frost). Look at it this way: If you have a colder winter, you get a break, a chance to stop and relax — and a chance regroup and plan for an even better garden next year, after the last frost is past.

The length of a growing season varies somewhat from year to year but is generally about the same. You probably already have a sense of your growing season, but if you really need to know, finding out is fairly easy. Call your nearest Cooperative Extension Service office, ask a knowledgeable gardener or garden-center staffer, or watch your local newspaper for the frost dates (which can vary from one year to the next). Many gardeners also use frost zone maps, like the ones here:

Bonnie’s Plants ( https://bonnieplants.com/gardening/first-and-last-frost-dates/ )

National Gardening Association ( https://garden.org/apps/frost-dates/ )

Here’s how to calculate your growing season: Suppose you live in Denver, Colorado; your last frost is May 3, and your first fall freeze is October 8. That gives you 157 days in which to garden. Or suppose you live in Las Vegas, Nevada; your last frost is March 7, and your first fall one is November 21. You get 259 days of growing.

Frost dates given in tables and maps are only approximations because predicting vagaries of weather from year to year is next to impossible. If you’re a higher-risk gambler, go for the earlier spring frost free dates and later fall dates; if you want to play it safe, choose the later last frost spring dates and the earlier fall frost dates.

Winter doesn’t mean a gardener can or should be idle in the downtime. You can find plenty to do if you’re so inclined to capitalize on the “shoulder seasons.” You can be plotting for the future, starting seeds indoors with the plan to put them out in the ground the minute the last spring frost passes; you can be reading and discovering more about plants; you can be fussing with cleaning and sharpening your tools; you can enjoy yourself as you care for indoor plants; and you can be placing orders with mail-order suppliers — all activities that feed into the process and joy of having a wonderful garden.

Despite all the zone maps and all the research, hardiness remains an inexact science. Although some plants turn out to be surprisingly tough, others succumb unexpectedly. The easiest thing you can do is to set your sights on plants said to be appropriate for your area. Here are some tips on deciding what you can grow, even if you’re not sure about the zone:

Peek at your neighbors’ yards. Chances are that if a type of plant is succeeding right nearby, it can grow well, survive, and thrive for you, too.

Buy local. When you get plants that were raised in your area (not in some distant place or coddled in a greenhouse), they’re much more likely to be able to handle whatever your local weather dishes out. After all, they’ve already experienced some of the harsher conditions and survived so the seller can offer them to you. Production fields out back or right nearby are your cue.

Grow native plants. Plants that come from your area or region — ones you’ve seen growing in the wild, perhaps, or certainly in local parks or botanic gardens — are sure to be well-adapted and set not only to survive but to prosper. How do you know whether a plant is native? Ask where you buy, or look it up.By the way, some local nurseries that promote or segregate native plants may also have nice selections or cultivars for you to choose from — improved versions of native plants (they may have smaller or more-compact size, different flower colors, bigger or longer-lasting flowers, and so forth); keep an eye out.

You can, however, force plants to grow in your hardiness or frost zone by taking advantage of microclimates (pockets of different growing conditions) or by using tools to extend your growing season. The following sections tell you how you can sometimes beat the zone system.

Features in your yard, both natural and human-made, often modify the overall climate and create small areas with distinctly different environmental conditions (including hardiness zones). Here, your zone rating may go up or down by one or possibly even two levels, changing your planting options.

A microclimate (a small, usually isolated area that is warmer, cooler, drier, or wetter that most of its surroundings) can be anywhere from a few feet wide to a few hundred feet wide. Examples of a microclimate include a low area, a south-facing area, the north side of your house or other structure, an exposed hilltop, a slope, any enclosed and sheltered area, a spot close to the foundation of your heated basement, and so on.

Look for marked differences in these areas: