Know Your Zone: Understanding Your Local Weather
The United States land mass covers nearly 3.8 million miles. Within the country there are weather extremes that have ranged from -80°F in Alaska (1971) to 128 °F in Arizona (1994). To help gardeners and growers select plants that will survive and thrive in their part of the country, the United States Department of Agriculture (USDA) compiles a Plant Hardiness Zone Map, an excellent tool for any gardener.
The most recent map, published in 2012, is based on the average annual extreme minimum winter temperatures at a given location. Scientists compiled the map based on data collected over a 30-year span.
Hardiness zones do not reflect the coldest it has ever been or ever will be where you garden. Instead, the zones tell the average lowest winter temperature for a given location.
Low temperatures during the winter play a key role in the survival of plants at specific locations. Knowing your hardiness zone can guide you in the selection of winter-hardy plants. You can find the hardiness zone for your state and the average annual extreme minimum temperatures at the USDA’s web site: http://planthardiness.ars.usda.gov/PHZMWeb/
Microclimates: Gardening at the Edges of the Hardiness Zone
Weather patterns are constantly changing. Some gardeners opt to try their luck at growing plants that may not survive winter cold in their area. For me, that’s been one of the enjoyable challenges of gardening in the Chicago area, where some winters have produced -80°F wind chills, while other years, we’ve had 50°F days in January.
I garden in Zone 5b. When buying perennials or shrubs that may not be hardy in our area, I look at microclimates in our garden. A microclimate can be a spot in the garden protected by a hedge, a fence, a garage or a house. If the plant I’m buying is rated Zone 6 (which is typically warmer than Zone 5 in winter), I look for a protected spot away from winter winds to plant it.
Microclimates can be warmer or cooler than other spots in your garden. For example, my vegetable garden sits seven feet lower than the front borders. Because it is low, the cold air settles there first. In spring and in fall, I must provide additional protection for vegetables (covering them with pots, row covers or cardboard boxes at night, so they don’t become frost damaged).
One of my favorite smaller trees is the Japanese maple (Acer palmatum). I’ve learned that this plant prefers Zone 6 even though it is sometimes listed as hardy to Zone 5. It has been notoriously fussy in our garden because I’ve planted some of the trees on the west side of our house where they were blasted by cold winter winds. After losing a few small trees, I planted some on the north side of the house, where they receive part shade and they’re protected in winter. There, they’ve survived and thrived over the past five years.
Panicle hydrangeas, on the other hand, are hardy to Zone 4, which can dip down to -30°F to -40°F during winter. I grow several of these beautiful shrubs out in the open and they are well adapted to our Zone 5 winter weather.
When considering a tree, I look at the tag to see if the grower has listed a hardiness zone. For example, if the tag (or grower’s web site) lists the plant as hardy in zones 4 – 9, I know it will likely survive in our zone’s extreme winter temperatures. You can find a list of cold-hardiness ratings for many woody plants at the U.S. National Arboretum’s web site: http://www.usna.usda.gov/Hardzone/hrdzon4.html#5
Other Factors
The hardiness zone map is a great tool for gardeners, but it’s just a guide. In time, you will have hands-on experience and knowledge about the spots in your garden that warm up first in spring or cool down quickly in fall. Think about those places when you’re buying plants.
Consider that in early autumn, a zone may experience extremely cold weather. This can injure plants even if the temperatures don’t reach the average lowest temperature for your zone. Very warm weather in midwinter followed by a sharp change to more seasonably cold weather can also injure plants.
An 18-foot tall Dawn Redwood tree placed on the west side of our house, quickly leafed out one March when the weather hit 80 degrees and then dropped to freezing the next day. It was not prepared for those conditions and it died. Perhaps if it was planted elsewhere in a protected spot in the garden, it would have survived.
Wrapping the trunks of young trees in fall can help prevent them from cracking during the winter. When in doubt, I’ll wrap smaller shrubs in burlap to protect them from drying winter winds.
Besides hardiness zones, other factors contribute to the success or failure of plants. Wind, soil type, soil moisture, humidity, pollution, snow, and winter sunshine can greatly affect their survival. Where you place a tree or shrub, how you plant it and care for it also influences its survival. Some plants can survive a short period of exposure to cold but longer periods of cold weather may injure or kill them.
Additional Online Plant Hardiness Zone Resources
Definition. https://en.wikipedia.org/wiki/Hardiness_zone
What’s New? http://planthardiness.ars.usda.gov/phzmweb/AboutWhatsNew.aspx
Interactive Zone Map. http://planthardiness.ars.usda.gov/phzmweb/interactivemap.aspx
User’s Guide. http://planthardiness.ars.usda.gov/PHZMWeb/Help.aspx
Perennials by Zone. https://www.plantdelights.com/pages/plant-hardiness-zones
History of Zone Maps. https://www.plantdelights.com/blogs/articles/plant-hardiness-zone-maps
1. Check Your Tools
We have all been there, we go to start digging and the handle to your shovel is cracked. Now you have to make a trip to the hardware store for either a new handle or a new shovel completely. Not only does this eat up valuable gardening time, it takes away any momentum you had built up.
You also should check the sharpness of any of your cutting tools. Pruners, loppers, saw blades, lawn mower blades, or anything else that you might need to cut with. Not only are sharp, well maintained tools better for the actual cut on the plant, it is safer for you. There have been numerous stories of a dull axe blade, bouncing off of the log and hitting a person, or the handle comes off because it was worn. You should also put a good edge to any of your shovels; it will make the digging much easier.
Lubricate and clean any moving parts. Those pruners that have been sitting around since last fall have probably gotten a little rusty and stiff, unless you are a very conscientious gardener that cleaned them before you put them away. I will also give you a handy tip here to use next fall: you will want to put a light layer of some kind of oil on your tools, i.e. shovels, pruners, etc. Fill a five-gallon pickle bucket with sand, about ½ to 2/3 of the way up. Then get some old used motor oil and pour a couple of ounces in the sand, mix it up real well. When you have that done, stick the shovel or any other tools in and out of the bucket a couple of times. The sand will help clean any rust or dirt off and the oil will apply a thin protective coating to it. You can also get some Linseed oil for the wooden handles, to help protect them. I don’t recommend using that oil on plastic handles; it will only make them slick.
2. Check Your Irrigation and Water Hoses
Rain, from Mother Nature, of course is the best type of water to use, but let’s be realistic-she does not always deliver when we need her to. So irrigate we must! If you have an irrigation system in place, check all of your heads for clogs, breaks, or places that there might be leaks. Soil and debris can accumulate over the heads, not allowing them to pop up. PVC pipes can crack over time or if they were not drained properly before freezing weather hit; run the irrigation to see if there is any seepage. This is also a good time to check your timer and make sure it is operating properly.
Okay, so lets say you are not one of those that are lucky enough to have an in place irrigation system and you water by hand, like me. This is the time to be checking your garden hoses for leaks and cracks. Rubber hoses dry rot over time and will start to leak or create weak spots that will eventually bust. If you have a hose that is over 4 or 5 years old, you might want to consider replacing it anyway. Check any of your nozzles that you use, they will also tend to get worn over time. Something that many people forget to check are the washers that fit in the hose end of a nozzle, they too can dry rot and crack.
3. Three Words: Sanitation, Sanitation, Sanitation
If you did not do a good job of cleaning up all of the leaf litter, dropped fruit and other debris last fall, I strongly urge you to do that! Not only does it make for a cleaner, neater appearance it can be life saving to your future crops. Diseases, fungi and insect larvae can grow over winter and it will rear its ugly head faster than you can blink an eye. This is also the reason to practice rotating your crops; in other words, don’t plant the same thing in the same spot, year after year. If you had any kind of disease or fungus issues last year, do not throw your debris in the compost bin, burn it or toss it in the trash.
4. Make a List and Check it Twice
Hopefully, you kept pretty good records from your previous gardens? Think back to what you did last year, what worked, what didn’t, and what you wished you had planted. The definition of an idiot is to do the same thing over and over again in hopes of a different outcome. If that certain type of tomato did not work in previous attempts, try something different. Make a list of what did work, and then build on that. Something to keep in mind, and I understand your crystal ball is probably still broken, try to think about your upcoming year. Do you foresee a very busy work year and your garden time may suffer? Then stay away from high maintenance plants. Roses here in the south come to mind, they are needing to be sprayed with a preventive fungicide rather often, if you miss a spray or two and the fungus hits, it is hard to rid your yard of it. An ounce of prevention is worth a pound of cure is actually a pretty good saying.
5. Stock Up on all of the Products you use Regularly
This goes along the same lines as checking your tools. Nothing will break your momentum or steal your gardening time quicker that finding some nasty little insect eating away on your favorite plant and not having any insecticide to apply. Fungicide can fall into this same category. Granted, it may not be a life and death situation, but the sooner you can get a handle on either of these situations, the better.
Fertilizer is not a bad thing to be stocked up on either. How many times have you been out working in the yard and realized it was time to feed something? Then you realize you don’t have any of that particular food. You can feed it with something else, which might be okay if it is a similar product. You can run out immediately and get some, killing your time again. OR, if you are like me, say to yourself, “I will get some next time I am at the store”, then forget all about it the next time you are at the store! Here again, a list is a good thing. Take inventory of what you use, what you have, and then make that list of what to get.
I am sure there are many other things that you need to do before you get down and dirty in the yard this spring. I wanted to give you a list of the “sometimes forgotten until it’s too late” items.
Happy Growing!
-Darren Sheriff