If you’re like us, you planted your flowers Mother’s Day weekend. Even with Colorado’s unpredictable springs, that date is generally in the clear for a hard frost. It has snowed as late as Father’s Day, but you have to live your life and try not to think about snow in June. We planted our winter squash, corn, and beans on May 1st because the forecast looked warm and damp. Flowers went in the ground and indoor-started veggies moved outside on May 7th or 8th. Yesterday it was 88°, but today, May 20th, we could get 3-5 inches of snow and the forecast calls for an overnight low of 28°. Tomorrow, the low is 30° and then things start to warm up to the mid-50s by Monday and 70° by Wednesday, with lots of rain between now and then. The precipitation is more than welcome, but the cold makes us worry about the garden. We take comfort in data, so we went in search of how cold is too cold for our plants. 

Here’s the breakdown of how cold affects our homestead, by the numbers. 

Bees

Our honeybees pulled through the winter, but we just split them into a second colony about ten days ago. We’re a little worried about the queenless hive being able to keep all the brood and queen cells warm enough, but the split, which has the queen and a smaller nest, should be fine. 

• 41°: the body temperature at which a bee will die.
• 93°: the average temperature at the center of the winter cluster, with brood present.
• 57°: the temperature at which bees form a tight cluster
• 45-50°: the temperature at which bees enter a state of torpor 

Dampness and wind are more likely to harm bees than the cold is.

Garden

Germination and seedling growth are highly dependent on water and soil temperature.

• 25°: hard freeze
• 28°: for 5 hours: the temperature at which most plants will freeze
• 32°: the temperature at which most seedlings will die. 

Evaporation will help raise the air temperature around the plants, so watering deeply in the evening can help, as can covering plants before the colder air sets in. We are using the alpacas’ pool, beach towels, tarps, outdoor blankets, old sheets—basically anything we can find—and I’m running the clean towels and sheets through the dryer first for good measure. And then I’m saying a prayer. 

I feel really lucky that I decided to plant peppers, tomatoes, and eggplants in the patio garden because I can move these more heat-loving plants inside for the weekend. I just have to keep the toddler out of them. 

Orchard

Our apple and pear trees are beyond the flowering stage and it looks like many of the blossoms have been pollinated (thanks, bees!). Julio found this guide to critical temperatures for fruit trees. It looks like our trees should be okay, for the most part, and enjoy a drink from all the precipitation. 

• 28°: the temperature at which 10% of buds will die.
• 25°: the temperature at which 90% of buds will die.

Alpacas

• 2 inches: how much fleece each alpaca has grown on her torso right now. 

They’re wet, but probably enjoying a break from being hot. Alpacas can tolerate very cold temperatures, provided they have a windbreak.

I was in the middle of writing this when the snow started, so I had to run outside and cover the babies. Now, I’m sipping stress relief tea and praying for the garden while taking deep breaths. Best wishes to you, fellow Front Range gardeners. 

We will update here with how the forecast played out and if our plants survived.