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Extending Your Vegetable Garden into the Fall
It is the middle of harvest time for many of your summer crops, but instead of starting to wind down for the year, it is the perfect time to plan your fall garden crop rotations.
It may not make sense to try to stuff more plants into what already seems like a jungle, but extending your vegetable garden into the fall is easier than it sounds.
The payoff: You keep your harvest going deep into the winter.
"For man, autumn is a time of harvest, of gathering together. For nature, it is a time of sowing, of scattering abroad."
When you grow a new rotation of annual crops in the fall/winter, you will avoid many garden summer problems, such as pests, watering, bolting, etc.).
Although the days get shorter in the fall, temperatures tend to be more consistent, and insects slow down their lifecycles to settle into hibernation.
Picking root crops in the winter is also advantageous because root plants tend to convert starches to sugars during the winter to warm up the plant and keep it alive during cooler temperatures.
Carrots, parsnips, beets, and winter radish will all be much sweeter and less woody if picked in the winter and early spring months.
Many brassicas, lettuces, and spinach will flower and become bitter (as they put their energy into producing seeds) if they sense the temperature rising above a certain level (known as photoperiodism).
Growing them in the cool of the fall will ensure that they still produce a healthy abundance of sweet and tender leaves.
Cloches and Coldframes to Extend the Harvest
Using cloches or cold frames (like the one pictured at the top of this blog) are great ways to extend your harvest in the fall and start your harvest early in the spring. These are simply boxes or containers put on top of your crops to keep them a few degrees warmer than the outdoor temperatures.
Here Alea Milham, of the blog, Premeditated Leftovers, uses old milk jugs, blender pitchers, and many different items to serve as cloches for her fall and spring gardens.
"My favorite item to upcycle and use as a cloche is 1-gallon vinegar jugs. Like milk jugs and plastic juice bottles, they have a lid, so I don't have to make one. However, unlike milk and juice containers, the lid on a vinegar jug is attached, so I don't have to worry about storing the lid when I'm not using it. I just pop the lid open during the day and snap it closed in the evening.
I use vinegar in cleaning and laundry, so I accumulate them throughout the year. I cut off the bottom of the jug to use them as a cloche. This makes it easy to stack them on top of each other when not in use."
Antique Cloches & DIY Coldframes
You are likely to find beautiful garden cloches such as these in antique Victorian ones in Europe's antique stores.
Master Gardener and garden blogger Jeanne Grunnert recommends an easy garden installation, and that is to simply add windows to existing raised beds.
Finally, bringing in beloved warm-weather herbs such as lemongrass and rosemary, crops like peppers or tomatoes that may still bear fruit indoors is also an acceptable way of extending your harvest. So don't discount doing that.
When all else fails, you can always grow your own sprouts no matter what the weather is like outdoors.
Fall Garden Crop Rotations
John Jeavons' book, "How to Grow More Vegetables," tells us that we can categorize our annual crops into three sections:
- Heavy feeders (our star players that use up a lot of minerals in the soil such as tomatoes, squashes, and brassicas like cabbages and cauliflowers)
- Heavy-givers (nitrogen-giving legumes such as peas and beans)
- Light-feeders (leafy greens that do not need so much fertilization to grow such as carrots, parsnips, beets, and other root crops except for potatoes)
If you grew a lot of tomatoes in the summer in a particular bed, it would be best to follow that with a planting of light feeders instead of brassicas in the fall.
The key to planning a fall garden is picking hardy vegetable varieties and using calendar math to count back from expected frost dates. The table below lists good candidates for a fall garden.
How to Know When to Start Fall Crops
Make your own Planting Calendar
There are several Planting Calendars available from gardening companies and seed stores. But you can easily create your own by following the steps below.
We live in zone 7 here in northern Virginia, and our first frost date is October 15, so our start dates for a few fall crops look like this:
- Select the variety of cool-weather crop you'd like to grow.
- Find out:
- What you crop's frost-tolerant temperature is. In the example above, the average lettuce is hardy down to 28F or -2C. Some varieties can tolerate lower temperatures.
- What its minimum germination temperature is. We will use this second temperature later.
- Find out when, on average, the frost-tolerant temperature occurs in your zone. You can search this on weather.com or weatherpark.com, by plugging in your zip code and pulling up your monthly average temperatures. Remember, we are working with averages here.
- Once you have found that frost-tolerant date (December 31, in the case of lettuces in Zone 7), work backward by subtracting the number of days to harvest from that date, December 31, minus 50 days is November 1. (You can plug in "50 days before December 31" on Google.) November 1 is now your possible "last day for planting" date.
- Go back to step 2 and find out when, on average, the minimum-germination temperature of that crop occurs in your zone. As in step number 3, you can use weather.com or weatherpark.com, plug in your zip code, and pull up your monthly average temperatures.
- Adjust the "last date for planting" date according to how long the weather will be at the ideal germination temperatures.
- Subtract two more weeks from that date to allow for the slower growth that happens in the fall. The result is the last day for "Recommended Planting"
One of the keys to growing for the fall is making sure the plants are big enough before the days get too short. One trick would be for you to start root crops very early in the summer (June) and then grow them in the full shade before transplanting them in the early fall.
Biennials & Perennials
The fall is also a great time to start your biennial and perennial plantings. Biennial crops (2 years life cycle) like onions/leeks, garlic, and swiss chard only flower in the second year and are hardy enough to survive frost conditions.
Planting them in the fall will give them a head-start for the following year's crop and allow them to establish a healthy root system.
Finally, transplanting berry bushes and other perennial vegetables or perennial herbs is an excellent thing to do in autumn because it gives these plants extra time to get acclimatized, with the possibility of getting a good harvest the very next year.
- Make a list of all the crops that you can grow in your garden this fall.
- Plan to extend their harvest even more by providing your plants some insulation from winter-temperatures.
- Read more about how to do this on the Gardening for all Four Seasons blog.