It’s 80! It’s snowing. It’s 70. It’s a blizzard! Welcome to spring in Colorado.
The last few weeks have been quite the challenge. Do I plant cold hardy crops or do I plan to shovel a foot of heavy wet snow? Planning garden activities is always a crap shoot in early spring. The apple blossoms shown here didn’t make it but many others did. If no other crazy snows happen, there will be plenty of fruit to harvest.
But today, I had to get the winter squash moved outside. They’ve grown so much in the last couple weeks, soon I won’t be able to untangle them from the window shades! The tomatoes and peppers will head out as long as I can keep night temperatures above 40. My cold frame is in use protecting the spring crop of radish, lettuce and beets. Instead I will use an upright mini-greenhouse the one shown here – for ~$20, a great deal from Hayneedle.
When starting seeds indoors the seedlings may seem robust in the window sill but are quite tender. They’ve had little exposure to drying winds, harsh sunlight, or a wide variation in temperatures. So you can’t just take your seedlings to the garden plot. A period of hardening off is required.
To harden off seedlings grown indoors:
- Expose to direct sunlight slowly
- Keep warm at night (>40 to avoid stunting growth)
- Ventilate on warm days to release heat
Nothing will kill off a seedling planted indoors faster than exposing it to too much sunlight too quickly. Leaves will burn. With Denver’s high altitude, I recommend not exposing seedlings to anything but a couple hours of morning sun when first put out. Check early and often to ensure the leaves are not wilting. Cover with shade material no later than 10 am in the first few days. The morning rays are at a lower angle and travel through more atmosphere. This filters UV rays more effectively, decreasing the risk of burn. After a week you can increase the exposure by an hour or two – and perhaps allow late afternoon sun. Mid-day sun should be avoided for at least two weeks.
My tomato and peppers were transplanted to plastic cups to better insulate their roots and keep moist. There are twenty four in total. I will need to do the same with the winter squash when the hubby brings home his venti ice teas from Starbucks.
Keeping temps warmer at night will reduce the risk of stunting the growth cycle. Below you see my greenhouse lit with a string of Christmas lights set on a timer. With lows of mid 30s being predicted next week, having the extra warmth will help. For the days that will reach 70 or above, I open up the zippered front to allow heat to escape.
The seedlings will stay in the greenhouse until Mother’s day. This is a pretty safe date to avoid a late frost, perhaps not snow, but frost for sure.
Want to know more about growing tomatoes? Read more here.