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.
Managing your microclimates
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.
Look for marked differences in these areas:
Water: Proximity to a pond, stream, wet ditch, or the ocean can make temperature fluctuations less dramatic.
Soil: Different types of soil can create protective or stressful growing conditions. For instance, clay soils hold moisture and heat and thus can reduce stress in dry or very cold conditions. Very sandy soils drain well and are great where excessive water is a problem, but in hot and dry conditions, they can put plants under severe water stress.
Wind: See how strong the winds are and how often you get air movement in a particular area. Winds are very drying.
Temperature: One spot may be significantly hotter or colder than its surroundings. Note that cold air often flows over a landscape like water, settling in low areas and creating cold pockets.A useful tool for determining temperature variation is the maximum-minimum thermometer (also known as a Six’s thermometer). This thermometer can measure the high and low temperature during a given time and can measure the extremes of temperature in a location. See Figure 3-1. This instrument is also available in a digital form. Recording thermometers can store temperatures and humidity levels over longer periods of time, and some can be synchronized to a spreadsheet on your computer. Apps come with some of these digital, remote-sensing devices and can track temperatures on you phone.
Light: Note dramatic differences in amount of daily sun and shade. Human-made structures (yours or a neighbor’s) as well as trees can contribute to these changing conditions.
© John Wiley & Sons, Inc.
FIGURE 3-1: A maximum-minimum thermometer gives you an idea of the outdoor temperature ranges in your area.
Cheating the system: Creating microclimates
Ah, here’s where gardeners can and do cheat their zone ratings so they can successfully grow plants they shouldn’t be able to and satisfy their zone envy. You can actually create microclimates (see the preceding section for general info on microclimates). Usually, the aim is to raise the temperature. For example, you can create a nice Zone 8-ish spot in a colder Zone 7 garden by employing a few gardening tricks:
Safety in numbers: Planting less-hardy plants in groups helps make them more resilient and better able to withstand temperature extremes and drying winds. The local humidity is likely to be higher in a crowd, too.
Mulch: A layer of organically rich mulch moderates soil-temperature fluctuations. It also helps hold in soil moisture so you don’t have to worry about lack of rain or having to water quite as much.
Heat traps: These structures help retain heat. Row covers, hot caps, and cold frames (see Figure 3-2) are well-known ways to trap heat, thus raising the immediate temperature and/or protecting vulnerable plants from cold weather. You can purchase heat traps or build your own. If you want to get fancy, you can add a heating cable to the soil of the cold frame with a thermostat. Then it becomes a hot bed or a miniature greenhouse.© John Wiley & Sons, Inc.FIGURE 3-2: Putting a cold frame to efficient use.
Water: Proximity to water has a moderating effect on temperature, so you may have luck pampering a slightly tender plant by growing it next to a water feature on your property (natural or artificial).
Wind and sun blocks: Fences, walls, buildings, and other structures offer shelter from drying winds and blasts of snow. Warmth and humidity can build up close to them, allowing you to coddle some tender plant. They often also create more shade, which can be cooling or inhibiting, depending on your plant’s needs. You can make a simple inexpensive temporary cold frame with bales of hay, placed in a rectangle and covered with a glass window or door sash.
Bending the rules to stretch your growing season
Maybe it’s the rebel in you, me, and all gardeners. Maybe it’s natural restlessness. Maybe it’s an urge to make maximum and efficient use of available time. But gardeners do like to try to push the envelope in order to grow more or better or different plants.
You can dig up many tricks and techniques along these lines, and you certainly may come up with a few of your own as your experience grows. The following sections describe some favorite rule-benders that you can try if appropriate to your garden, your needs, and your climate.
Incorporating warming tricks
If frost will damage a plant, perhaps you can still have it outdoors by shielding it somehow. This idea applies both to setting plants out a bit too early in the spring and leaving them in the garden a bit too late in the fall.
Use row covers, blankets, water walls (heavy pieces of plastic that have sections filled with water that holds heat) burlap, plastic sheeting, or extra mulch (compost, weed-free hay, pine straw, which is actually pine needles), or pine boughs. Water well; hydrated roots can withstand cold and drought better.
JACK FROST AT BAY
You may find you tried to stretch the growing season a little too far, or perhaps the weather experts missed the mark on the date of the final frost. A big chill is creeping up, and you’ve already used mulch and blankets as much as you can to keep the plants warm. What’s a gardener to do? Try a little emergency frost protection.