Cheating is not something we would necessarily recommend in most aspects of life, but when it comes to what you can and can’t do in our planting zone here in Bismarck—we are here to tell you that some rules are made to be broken (or at least bent a little)! As gardeners, it can be hard to avoid falling in love with plants that don’t necessarily ‘fit’ into the box of what is considered hardy in our planting zone. But despite what you may have heard from various sources, planting zones are not an absolute, black and white situation. We are firm believers that where there’s a will, there’s a way—and it is easier than you might think to ‘stretch’ the rules of a planting zone with the proper care and planting location. Here’s how!
What Exactly Is A Planting Zone Anyway?
In essence, planting zones outline the conditions of the different climatic regions in North America, which helps gardeners determine what will thrive and when to plant depending on where you live. It is a numerical system devised by the US Department of Agriculture (USDA) which is based on the coldest day of the year by region—plant hardiness Zone 1 being the coldest (where temps dip as low as -60° F, brrrr!) in the depths of the winter, and Zone 13 being the hottest. Interestingly though, the USDA actually revised the lines of these planting zones in 2012 to reflect warmth shifting north slightly.
Where Does Bismarck Lie on the Planting Zone Map?
Bismarck is located in planting zone 4a, which means that the minimum average temperature is between -25°F to -30°F. In general, the last expected frost date is around May 12th, while the first expected frost date in the fall is around September 25th. As a rule of thumb (aside from cold-hardy vegetables), it is recommended not to plant annuals or vegetables outdoors until Mother’s Day (or May 15th.)
How To Work Around Bismarck’s Planting Zone Rules
The thing with planting zone rules is that they are more of a guideline, not a strict science—especially as our climate changes and we are seeing warmer fluctuations. Final frost dates can fluctuate by the years, and many plants that aren’t officially ‘hardy’ in your growing zone can surprise you so long as they get a little bit of extra TLC and are planted in a way that gives them a better fighting chance to survive. Here’s a few ways that you can maintain happy, healthy plants even if they do not technically fall within Bismarck’s particular planting zone rules:
Sow Seeds Indoors: We have short summers here in Bismarck. If you are in the market for a veggie garden, you can stretch the system of Zone 4’s shorter growing season by starting seeds indoors ahead of schedule instead of waiting until the last risk of frost has passed to do so outdoors. This will get your plants started a little earlier, in turn extending your growing season.
Protect Tender Perennials: If you are planting more tender perennials with the hopes that you can keep them in the garden year-round, you will need to cross your fingers and hope for the best, knowing there are no guarantees—but there is hope! Give them the best chance at survival by providing as much extra protection from the elements as possible. Some of these measures once the cool weather arrives may help: extra layers of mulch, plant protector bags, and frost shields/blankets. Aside from that, hope for a mild winter and see what comes back next spring.
Identify & Take Advantage of Microclimates: There are techniques you can harness, like planting on a south-facing slope or even on the south-facing side of your home versus the east or north. Shadier parts of your garden experience less intense temperature fluctuations but are slower to melt, while rock gardens will provide more warmth and protection for smaller plants that you think might be a little more vulnerable to the elements. You can also take advantage of planting near hardscapes like stone patios as they absorb heat during the day, which then radiates back out at night.
Raise The Humidity: If you’ve got your eye on tropicals that don’t tend to fare well in Zone 4, you can fabricate higher humidity levels than what the natural conditions offer to keep them happy. For potted plants, place a pebble tray underneath it. Alternatively, spritz your plant with water every day or every other day to give the environment a more tropical vibe. However, tropicals will need to be brought in once the cooler nights arrive; there is no chance of them surviving our Bismarck winters.
As you can see, there are plenty of ways that you can bend the planting zone rules a little and still enjoy plants that are technically a little more tender when it comes to Bismarck’s planting zone! For more tips and tricks or to pick up some new plant babies, stop by Plant Perfect to check out our extensive collection of perennials and annuals.