Season Extenders Bring Freshies to our Spring Plates

Sick of wilted boxed salad greens and bunches of kale that are past their prime?  One of the many things Yampa Valley gardeners have going for us is our cool climate – perfect for cool-season crops and especially greens of all kinds.  Add simple “season extension” to your bag of gardening tools and start early to have salad and baby greens in as little as 30 days!  Season extenders can also be used to start tender frost-phobic vegetables and herbs like tomatoes and basil well before our average last frost date of mid-June.

First, a brief primer on basic gardening terminology.  Perennials live from one growing season to the next, storing their energy in their roots during the winter – locally, think shallots, asparagus, horseradish and rhubarb; reliable perennial herbs include thyme, French tarragon and chives.  Annuals grow for only one season; they are either root or leaf crops – radish, beans, squash and basil.  Additionally, all plants have a hardiness characteristic. Most cool-season vegetables can tolerate light to moderate frosts, and many become bitter or tough as temperatures rise.  Seeds of warm-season plants will only germinate when soil temperatures are warm enough, and our cool summer nights can stunt their growth and ability to flower and produce fruit.  Warm-season plants wilt and die back at the first hint of frost.

Examples of cool-season annuals include root vegetables like carrots, beets, radishes, turnips, parsnips, kohlrabi, potatoes and the onion family; leafy cool-season crops include leafy greens, peas, broccoli, cabbage, cauliflower, and Brussel sprouts; parsley, cilantro, dill are cool-season annual herbs that do well in our climate.  Warm-season annuals include the coveted tomato, corn, winter squash, beans, cucumber, all the melons and gourds, eggplant, peppers, basil and marjoram. 

Season extenders are simple enclosures that create a microclimate suitable for cool-season annuals to thrive until summer temperatures drive them to seed.  They can be as fancy as used windows supported at an angle on a raised bed, with hinges to allow venting, or as simple as a half circle of sturdy wire mesh covered with row cloth or plastic.  Plastic covers do not breathe like woven row cloth and can easily overheat during a sunny day.  These covers can give plants as much as 10 degrees of protection – it may be 20 degrees out, but the plants experience 30 degrees.  Leafy greens can tolerate short periods of sub-freezing temperatures, so they easily live through these short dips into cold terrain.

The first step in building a spring greens bed is to find a south-facing area, sheltered from winds and foot and pet traffic.  It may be an existing part of your garden or an existing raised bed.  Raised beds are easiest to attach supporting structure to.  Greens have shallow roots, so a couple pieces of otherwise unusable framing lumber will work great for a small raised bed.  Construct a box or two and fill with good bagged garden soil or potting mix.  Decide what you have around to support a cover – windows from Milner Mall, wire mesh from the store and row cloth.  These photos provide some ideas.

Wet the soil and gently spread and press in seeds for greens, following the instructions on the seed packet about planting depth.  Keep moist, not drenched, and within a few days you will see the first sprouts.  Within a couple weeks, you can start to thin the seedlings and pick your first tender leaves for salads.  And you thought the season for “freshies” hadn’t yet begun!