A few years ago, I discovered a great use for some of my leftover vegetable seeds. I was trying to plant lettuce for a fall crop, but waited until mid- to late August to plant the seeds. By the time the weather got cold, my lettuce plants were about 2” tall. Hmmm, I thought, they’re not going to survive the winter. Oh well. And then I covered the whole bed with leaves, included it in my winter watering, but generally forgot about it.
When spring came along and I was cleaning the leaves out, I discovered my little lettuce plants had made it. Well, I was pretty sure they’d produce awfully bitter lettuce if allowed to mature, so I turned them under…. all but one, which escaped my notice. Imagine my surprise a few weeks later when I went outside to plant lettuce seedlings I’d purchased to see the single lettuce alive. I left it there, planted the store-bought seedlings nearby, and waited to start harvesting lettuce. Amazingly, the single, over-wintered lettuce was able to be harvested weeks earlier than the purchased seedlings. So, my accidental late planting of lettuce led me to a new use for my leftover seeds: fall planting vegetable seeds to get an earlier start in spring.
By Susan Perry
Colorado State University Extension Master Gardener in Larimer County
After this accidental discovery, I did some research and then tried the same thing with pea seeds. Just as I would if I planted peas in spring, I soaked them overnight and planted them – in late October, covering the bed with leaves and including it in my winter watering. I’ve done this for several years successfully, with about 90% germination early in the spring when the ground is warm enough. Conventional wisdom says plant your peas on St. Patrick’s Day, March 17. This year, my baby peas were between 1- and 2-inches tall by March 12. At that time, I planted just enough peas to fill in the gaps where nothing germinated.
It won’t work for all my seeds, but it has worked for lettuce and peas, and would probably work for other things like spinach, chard, cabbage and kale. I’m certain it wouldn’t work for warm-weather vegetables like tomatoes, peppers, or beans. The trick is selecting cold-hardy vegetables that will go dormant during the winter and start growing again once the soil temperature becomes warm enough in the spring. Some protection, such as a thick layer of leaves, is required to help insulate the seeds/seedlings during extremely cold weather.
Garlic works when planted in the fall in Colorado, so onions starts might too, as long as they’re planted in a well-drained location. Radishes, carrots and beets that are mature can be harvested even after the ground freezes — it may require a chisel, but the taste will be fine. However, these root crops will become inedible if subjected to freeze-thaw conditions and should be completely harvested by early spring, before the plants send up a flower stalk, when they become bitter. So it may be best to plan to harvest them for use in holiday dinners. Often the cold fall/early winter temperatures result in a sweeter flavor.
One of the challenges of planting in late summer is germination: the warm air and soil temperatures or drier conditions can result in inconsistent germination of cold-loving vegetables. Ensure soil is consistently moist and mulch to help keep soil temperatures cooler. Conversely, in the winter, mulch, leaves, or a blanket of snow will help keep the soil temperature a little warmer.
When planting in fall to overwinter for a spring harvest, keep in mind the location of your garden. Low spots tend to be colder and are places where water may accumulate. Good drainage is important during the winter to enable plants to survive until spring. Be sure to provide water at least monthly when there’s no snow cover or during extended warm winter periods to avoid stress due to our drying winter winds.
Another challenge comes during winter and spring, when we experience surprise cold snaps (think Feb. 5-6, when daytime temperatures didn’t crack zero.) In Colorado, we can have 50-degree days followed by single-digit days, so keep extra leaves or other mulch handy. You may also need floating row covers for an added layer of protection. As nighttime temperatures rise above freezing consistently, gradually remove some of the leaves/mulch to allow sun to reach the plants.
In the end, it is a gamble but I always ask myself, what’s the downside? I wasted a little time and used up some leftover seeds. The upside is I might have some homegrown vegetables earlier in the spring.