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Have you ever wondered why the rosebush that was supposed to survive Fairbank’s extreme weather died on you last winter? Or why the tree rated zone 2 just keeled over?  I wondered this for years, myself.

But let’s start from the beginning.  Selecting plants that will mature and produce vegetables or fruits in Haines’ short summers can be challenging, especially if those plants are perennials and need to survive our fitful winters.  

When selecting annual vegetables, herbs and things like tomatoes, look for varieties that ripen or produce early (70 days or less) and that are listed as cold hardy, good for northern gardens and do well in wet, rainy conditions. Remember that “cold hardy” is a relative term.  A cold hardy pumpkin might thrive in night temps of 60°F, but that won’t cut it here.  Our warmest night temperatures are rarely above 55°F. 

For perennials such as fruit trees, bushes, and ornamentals, you’ll need to pay attention to the Hardiness Zone.  The US Department of Agriculture created a map dividing North American into 11 zones that are defined by extreme minimum temperatures.  Zone 1 can get down to -50° F.  Zone 11 doesn’t get colder than 40°F.  Haines ranges from Zone 4 (up the highway) to Zone 5 in town.  Again, look for cold hardy and early producing or early ripening varieties.  Choose varieties that can ripen in cool maritime climates and that ripen no later than late August, or early September if you have an ideal, southern facing spot.  

Keep in mind that many plants are listed as being perennial, especially when those plants have been shipped up from nurseries in the Lower 48.  Therefore, you can’t necessarily trust labels, even when they are listed as hardy to Zone 5.  This is especially true of ground covers and bulbs.

For the vegetable garden, cool weather crops such as the cabbage family, lettuce, Swiss chard, green peas, short carrots, potatoes and many others do well, but things like Brussel sprouts struggle to mature in time, especially as our falls are often cool and rainy.  Most beans die or fail to produce as they require more heat than our summer can provide.  This is also true of winter squash, corn, and even zucchini (summer squash) which can often get stunted or even killed by our cool springs.  Zucchini often suffer from blossom end rot due to rain—remove the blossom from the fruit as soon as it’s loose to help prevent this. Row covers can make a huge difference for many crops, giving them a heat boost and also protecting the cabbage family from root maggots.  Tomatoes, cucumbers and basil require a greenhouse to be productive and sweet.  Cucumbers are particularly vulnerable to cool soil temperatures and will shrivel and die in temps under 50°F.

For ornamental flowers, avoid those that require warmth, especially at night such as morning glories.  There is a wide selection of annual flowers that will thrive like classic petunias, begonias, marigolds, pansies and the famous nasturtiums that can take over your whole yard, given half a chance.  Often plants that burn up in the Lower 48’s heat like lobelia will last all summer long here and many perennials can be grown as annuals if started indoors very early or purchased as starts.

So, you’re asking, why did that Fairbank’s rose perish? 

Many plants can handle extreme cold, but not many can handle fluctuating back and forth.  This is because of something called chill hours.  Chill hours are the accumulated hours a plant needs between 32°-45°F before it will come out of dormancy and start to bud.  Because of our cool falls, some plants (like many roses) get their necessary chill hour requirements before we even get our first snow.  When the temperature rises in January and stays in the 40s for two weeks, the rose starts to wake up, thinking it’s spring.  Then the temp drops to 5 degrees and it’s sayonara little rose bush.  There are exceptions (Rugosa roses or rugosa hybrids for example) but most roses just can’t take our weather. 

When choosing perennials, look for plants with very high chill hours (700 hours or more).  Unfortunately, most nurseries don’t list chill hours in their descriptions.  You can, however, often find general information for a plant or variety with a quick online search.  

Finally, when selecting plants, use Haines’ best resource: our local community of gardeners.  Have a neighbor with a beautiful yard or vegetable patch?  Pick their brain. Ask them what varieties they plant, when and why.  Most gardeners are only too happy to chat for hours about our favorite pastime.

Blythe Carter owns and operates Blythe’s Garden