Weather Spark chart of average daily temperatures in Louisa County, Virginia
To find out more about your local weather statistics, go to WeatherSpark.com, and first look a the graph of average High and Low air Temperatures, and the chart below that. Here the average daily high in October is 71F (22C), the average nightly low is 49F (9.5C) and the overall daily average is 59F (15C). In November average temperatures are 9F (5C) lower and in December another 9F (5C) colder. The soil will stay warmer than the air for quite a while, which helps seed germination.
Harvest to Table logo
Stephen Albert of Harvest to Table in Northern California has run a great website with loads of good information, for decades. Nowadays it may be using AI (it gets repetitive), but the real info is in there, if you look. It is run as a SubStack, and has a generous free subscription version. Check outThe Complete Guide to Fall Vegetable Gardening: Planning, Planting, Growing, and Harvesting. This guide explains planning a fall garden, including deciding when to plant and calculating days to maturity; choosing crops; and everything from preparing the soil and protecting plants, to harvesting and extending the season. It includes crop-by-crop guides with details for planting, growing, and harvesting.
Watch for Nature’s Signals of the Deepening of Fall
The signs are there before the weather forecast lets you know. Stephen Albert lists these:
Nights begin cooling into the 50s and low 60s F (10–16°C).
Daylight hours become noticeably shorter
Soil temperatures decline
Morning dew becomes more common.
Tomatoes and squash begin slowing their production.
Sunflowers finish blooming and begin setting seed.
Goldenrod, asters, and other late-summer wildflowers come into bloom.
These natural signals indicate that cool-season vegetables will soon thrive.
By the time these things are obvious, you will hopefully have planned your fall and winter vegetable garden. The goal is to get crops established while there is still enough warmth and daylight to bring them to harvest.
Over-wintered Acadia spinach emerging undamaged from under the ice and snow. Ken Bezilla
Next figure when you think it will get that cold, with help from WeatherSpark.
Work backwards from the harvest date you want. Check the days to maturity for each crop. Then allow extra time, perhaps two weeks, for the shorter days and cooler temperatures of autumn. Different crops will have different last planting dates.
Soil thermometer. Photo by Green Living/Taylor
The Importance of Soil Temperatures
Also watch the soil temperature, which will tell you what you can plant when.
As the soil moves through several temperature ranges, be ready to plant different crops.
75–80°F (24-27C): Begin transplanting broccoli, cabbage and kale; direct-seed crops such as beets and carrots (and water them whenever needed).
65–75°F (18-24C): This is a good temperature range for many fall vegetables, including lettuce, spinach, carrots, beets, Swiss chard and Asian greens. If your Swiss chard survives the winter it will feed you plenty of leaves in spring
55–65°F (13-18C): This is an excellent range for later sowings of spinach, arugula and radishes, provided you still have enough days to mature them before it gets too cold.
Winter cover crops for vegetable gardens in zone 7a. Pam Dawling
This month, I’m writing about unusual greens for late fall and winter meals.
Spring Tower celtuce from Johnny’s Selected Seeds
Celtuce, Stem lettuce
Celtuce is the same crop family as regular lettuce. The difference is that it is bred to grow thick, succulent stalks, and that is the part eaten, raw or lightly steamed or stir-fried. It can also be pickled, or used as a gluten-free pasta substitute. Some people say the flavor of the stem is a crisp, nutty cross between romaine, celery and cucumber.
The leaves are eaten by people who like slightly bitter salad vegetables such as radicchio. Young leaves are edible about 5 weeks after planting and the stems are ready when about 12” (30 cm) tall, or shorter if you prefer. Trim and peel the stems, then chop however you like, rounds or diagonally-cut chunks. Celtuce goes well added late into miso or egg drop soup, or with tofu.
Purple Sword celtuce
Celtuce Varieties
As an Asian vegetable, Celtuce is also known as Aa choy. True Leaf Market (Kitazawa Seeds) has a Purple Sword variety. Green celtuce varieties are more widely available, such as Spring Tower from Johnny’s. I was entertained to discover that the fast-maturing spring lettuce Cracoviensis that I grew when I first moved to Virginia has since been classified as a type of celtuce. The killing temperature of outdoor unprotected celtuce is 20°F (-7°C). It bolts readily as spring starts to warm, but the leaves are not bitter and the stem is the prize!
Cracoviensis lettuce, or “red celtuce” Credit Southern Exposure Seed Exchange
Sowing and transplanting celtuce
Sow seed 1/8″ (3 mm) deep, about 1/4″ (6 mm) apart a few weeks before transplanting outdoors. For a continuous supply, sow every 2-3 weeks. Shade flats if necessary to keep the soil surface below 75°F (24°C) until germination. Transplant 8″-12″ (20-30 cm) apart in rows 12″-18″ (30-45 cm) apart.
Short term celtuce storage
Celtuce stems will keep for 3 weeks or so in a ziplock bag in a refrigerator vegetable drawer.
Jewels of Opar photo from Southern Exposure Seed Exchange
Aka fameflower, this is a heat-loving plant that can provide salad leaves in hot weather, and delicate pink flowers on spindly stems (nice filler for flower arrangements) followed by shiny ruby-red or orange-bronze seed pods, which are also useful in floral displays. Unlike celtuce, this is for those in hot climates (or try it in summer in mid-latitudes where lettuce is hard to keep growing in summer.) It grows 1’-3’ tall (30-90 cm) and as much as 2’-3’ (60-90 cm) wide. It doesn’t seem to suffer if grown thickly in the row. It forms dense mounds of succulent leaves (it’s related to purslane). The slightly succulent oval leaves make good salads or sandwich fillers. They are a nice size too: up to 4” x 2” (10 cm x 5 cm).
Jewels of Opar is a native plant and there are also cultivars such as Kingwood Gold and Limon valued by florists. It grows as a perennial in zones 8-10. It does self sow but not in a problematic way in zone 7. The evening-opening flowers attract bees and other polllinators.
September-sown shungiku (chrysanthemum greens) in January. Photo Pam Dawling
This Asian green has a distinctive flavor. It really is a chrysanthemum, not a lettuce, and not a brassica as most Asian greens are. Formerly called Chrysanthemum coronarium, Ismelia coronaria, Xanthophthalmum coronarium, or Pinardia coronaria, it also known as “garland chrysanthemum” or “chop suey greens” in English. It is known as “Kikuna” in western Japan, “tong hao” in Chinese, ssukgat in Korean and cải cúc or tần ô in Vietnamese.
Most chrysanthemums are perennial with poisonous leaves, but shungiku is an edible annual.
The flavor of the leaves was not at all popular with our crowd. I have written about our trial of this in our winter hoophouse to attract aphid predators in early spring. (We sowed in September, but our winter was too cold for them.) There are various colors of flowers. The flowers on the ones we grew were solid yellow, not banded with other colors. We bought seed from Small House Farm. Bevin Cohen says it does attract bees, butterflies and predatory insects, and would probably do well in the winter hoophouse, and could be provoked into bolting early in the spring.
Shungiku chrysanthemum greens. Photo Small House Farm
Rotations including unusual greens
Having non-brassica greens is a help with crop rotations.
A maximum of 1 year in 4 for brassicas is ideal to avoid disease and pest buildup. When possible, plant one year’s brassicas at some distance from the previous year’s, rather than in adjacent plots. The spread of disease can be reduced by avoiding walking through wet crops and by controlling weeds in the brassica family, such as rock cress, pepperweed, garlic mustard, and wild rocket.
Timing for fall crops
Planting dates for fall crops can be exacting because the cooling weather slows down the plants’ growth, and a day or two delay in sowing date can mean a week or two delay in harvest date.
The number of days to harvest given in seed catalogs is based on spring conditions – plants grow faster in warmer temperatures. To determine when to sow for fall plantings, start with your desired harvest date, noting when would be too late! Consult https://weatherspark.com to estimate when it will get too cold in your location.
Next subtract the number of days from seeding to transplant, plus the number of days from transplanting to harvest for that crop (given in the catalog description), plus the length of your ideal harvest period and another 14 days for the slowing rate of plant growth in fall compared to spring.
Some Eat-All Greens in early November. Photo Lori Katz
Eat-All Greens: Fall Cooking Greens
Eat-All Greens were invented by Carol Deppe, who explains them in her book The Tao of Vegetable Gardening . Carol grows and breeds vegetables in Corvallis, OR, in the Pacific NW, in a different climate zone from my home in central Virginia. Carol grows Eat-All Greens by broadcasting seed of one of her carefully chosen crops in a small patch. When it reaches 12″ tall, she cuts the top 9″ off for cooking, leaving the tough-stemmed lower part, perhaps for a second cut, or to return to the soil.
I decided to modify her idea for Virginia. Fall was a promising time of year for us to try this idea, as our spring planted greens only have a short season before they bolt. And summer is too hot, winter too cold. . . We sowed 9/16, got our first harvest on 10/21, 35 days after sowing, our second on 10/28 and our third on 11/3. Unlike Carol, we sowed our greens in rows side by side, enabling us to hoe the weeds. I doubt Carol has weeds.
You can read which greens we grew and which did best in this series of three posts:
By late December the greens were past their best. I seem not to have recorded harvests between 11/3 and 12/10, but I know there were some. We made a last harvest on 12/10, pulling the roots of the radishes and turnips we had in the mix. The daikons, Crimson Giant and White Icicle radishes did well.
We had a low temperature of 6F on January 5th that winter. Not much was left alive. Always enthusiastic to keep updating my list of cold-hardy winter vegetable crops, I took my notebook and walked the rows a few days later. Here’s a (short) list of the survivors:
Best were Morris Heading collards. Also still showing some life were Purple Top White Globe turnips, Ortolani Market Grower arugula and some (not all) of the Hanover kale (which is after all, a Siberian spring kale, not recommended for over-winter growing). I wrote up our whole Eat-All Greens experience for the January 2016 issue ofGrowing for Market magazine
Eat-All Greens rows with frost in December. Photo Bridget Aleshire
I developed clear ideas of what would I do different if we do this again. No chards, no beets, no kohlrabi. Thinner seed sowing, straighter rows (easier hoeing). Try some other Asian greens? Buy some of the specific varieties that Carol Deppe recommends. Maybe sow a week earlier. And a smaller patch! It’s fun!
Peanuts are an interesting and rewarding crop to grow on a small scale. Growers who offer farm tours will enjoy showing how the flowers “peg down” to develop the nuts under the soil, those concerned about local food security will appreciate peanuts as a source of locally grown protein and oil; and everyone can enjoy the challenge of trying a new crop.
Peanut Crop Requirements
Peanuts need a frost-free period of at least 110 days. Virginia type peanuts require 2,520–2,570 growing degree days (GDDs) above a base of 57°F (14°C). Consult Weatherspark.com to make sure you have enough frost-free days. One way of tracking GDDs is on the Climate Smart Farming Growing Degree Day Calculator website from Cornell, which can show you the season to date and the 6-day forecast, as well as the 15-year average and the 30-year “normal” for your location.
Peanuts like warm or hot conditions, with adequate but not excessive water. If you can provide these conditions, as well as relatively light, loose, free-draining soil and attention to controlling weeds, then I encourage you to give peanuts a try. We plant our peanuts in a raised bed, which helps provide looser soil. They can be hard to lift from heavy soil.
Carolina Black peanut. Photo by Southern Exposure Seed Exchange.
We get our seed peanuts from Southern Exposure Seed Exchange. Twenty-eight grams will plant about 25′ (7.6 m). Prepare a bed or row ahead of time. You can warm the soil by covering it with rowcover or plastic for 3–7 days before planting. The pH should be 5–6, and if calcium levels are at all low, add gypsum — the start of blooming is the latest time you can effectively do this. Calcium deficiency results in unfilled pods and low yields (see the “Peanut Production Practices” chapter in the annual Peanut Information publication from NCSU Extension for more on soil nutrient requirements). The NCSU website also has an interesting “Peanut Risk Tool and Field Log.”
Those thinking of pre-sprouting or transplanting peanuts should be alerted to a peculiarity of the crop: they do not germinate well without soil. Exactly what peanuts need from the soil remains a bit of a mystery. So if you want your peanuts to get an early start, don’t try to sow them in a soilless mix, or in paper towels or a glass jar. To successfully transplant peanuts, use actual soil or a sand/compost/soil mix.
Peanut Varieties
Carwile’s Virginia peanut. Photo by Raddysh Acorn for Southern Exposure Seed Exchange
If you have a relatively short growing season, I recommend starting with the 110-day variety Tennessee Red Valencia. It’s easy to grow, very productive and has large sweet kernels, 2–5 per shell. If you don’t want to hill, this variety is said to be the most accepting of this. Another 110-day variety is the unusual Carolina Black, an heirloom with a black skin. It’s sweet-tasting and slightly larger than the Spanish varieties. Virginia Jumbo needs 120 days, produces large rich-flavored kernels, 2 per shell, and prefers loose soil. Whopper also needs 120 days, and its claim to fame is obvious. Carwile’s Virginia is a 130-day heirloom variety with superior flavor and good drought resistance (though only average disease resistance). MorningChores.com has an excellent beginner description of seven pests and two diseases. Peanuts are prone to the same diseases as beans, with bacterial wilt being especially damaging. Sclerotinia blight is more prevalent at high pH.
Morning Chores’ Beginners Guide to Growing Peanuts
Sowing Peanuts
Sow around the last frost date. The soil temperature should be 65°F (18°C) at noon, at a 4″ (10 cm) depth, for 3 consecutive days. For us that’s late April. May is safer. Count back from your first frost date to find your last sowing date. The beginning of June is about the latest I’d want to try here. Shell the nuts (don’t split the kernels into halves) and sow 2″ (5 cm) deep, 12″ (30 cm) apart, in rows 30″–36″ (76–90 cm) apart. Inoculating the seeds with Rhizobium bacteria can produce enough nitrogen in root nodules to sustain the crop, as with other legumes. Active nodules are pink or red inside.
The seedlings may be slow to emerge, so preemptive weeding may be needed. If you have not interplanted, you could try pre-emergence flame-weeding. Peanuts are native to an area subject to periodic drought and fire, and have evolved to withstand heat. You can flame them soon after emergence, as the growing point is still in the soil. Older peanut plants may be damaged and then recover. The seedlings look somewhat like peas or clover. Because they grow slowly for the first 40 days, they will not thrive if you lose them in weeds (guess how I know?). Flaming or careful hoeing as soon as the peanuts emerge will effectively deal with broadleaf weeds. Grasses are not killed by flaming.
Small peanut plant . Pinterest photo
Peanut Cultivation
Once the seedlings are 12″ (30 cm) tall, you can hill them up, as you would potatoes, to increase yields. We skip this step —the peanuts have no difficulty pegging in the loose soil of our raised beds. We’ve grown Virginia Jumbo and Carwiles without hilling and got plenty of peanuts. But if you are not interplanting and have a good hiller attachment on a tiller or wheel hoe (or a visiting school group, perhaps), then hilling can deal with weeds and provide more loose soil for the nuts to develop in. Avoid disturbing the soil after pegging has begun.
Watering Peanuts
There are two periods when adequate watering is vital. The first is at planting, to ensure germination. The second is from 50 days after planting, when pegs start to enter the soil, until 2 weeks before harvest. This is the time when the pods are filling. Stop watering 10–14 days before harvest, to help the peanuts dry for storage.
Harvesting and Drying Peanuts
You can wait for a light frost to kill the tops, or you can simply harvest when enough peanuts are mature. You’ll have to dig some up and open them to see. The University of Florida has a helpful publication, “Methods to Evaluate Peanut Maturity for Optimal Seed Quality and Yield.” If the fall is wet, it might be best to pull or dig the plants early, when the seed is almost ripe, and dry them indoors. This will minimize losses from rotting.
Varying pod sizes on a peanut plant. Removal of all pods is critical, from match heads to full-size pods. Credit: Ethan Carter, UF/IFAS
In dry light soil, you can just pull the plant, and the peanuts will come up attached to the stems. Then you can bunch and hang them in an airy barn. Mice really love peanuts and will run off with them and stash them at a phenomenal rate, so be sure to set traps or provide a good cat. If the soil was dry and loose enough for you to pull the plant, the nuts will likely be relatively clean, so you can dry (and cure) them on the vine, which takes up to 3 weeks.
In heavier soils, dig the plants up lightly — no need to go deep. You can pull the nuts off the stems by hand and gather loose ones from the soil. For small-scale production, you can strip peanuts off the vines by dragging the plants through a V-shaped piece of equipment, from the far side towards yourself, letting peanuts collect in a tote.
If needed, wash the peanuts, spreading the loose ones out on trays to dry. Mold is an enemy when drying: moldy peanuts contain toxic aflatoxin, so get them dried quickly. Set up fans indoors, or dry the peanuts outdoors in the sun: 3–7 days is a likely amount of time. You could spread the peanuts on screens on wheelbarrows. Just wheel the barrow from place to place to catch the sun, and under cover if rain threatens. A second screen inverted over the first keeps mice away. This system works for very small-scale production. You could make mouse-proof lidded trays from rat wire and dry the peanuts on greenhouse benches, with fans.
Curing and Storing Peanuts
If vine-drying, you can also cure the peanuts on the vine, as described above. Otherwise pick the good nuts off the plants once they have dried and cure them in the sun for a few days. Peanuts will cure to a storable state in 2–3 weeks indoors at ambient temperatures or 6 days in a solar dryer of the type described in my book. It’s important not to heat the nuts higher than 85°F (29°C). Drying too fast causes skin slippage and kernel splitting. To find out when peanuts have finished curing, taste some. If they still have the watery crunch of water chestnuts, they are not ready; once they taste good, they’re cured. For long-term storage, a sealed container in a freezer works well. They need to be kept very dry. Like most seeds, peanuts are very good at drawing moisture from the air.
Immediately after harvest, you can eat all or some of your bounty, without drying or curing. These are a big hit! Here’s how we cook them for a party: fill a large pot two-thirds full of water, add 2 handfuls of salt and enough peanuts (in their shells) to fill the pot, but still have enough room to move. Cook for 5 whole hours, strain, and serve.
Roasting Peanuts
To roast peanuts, spread them shelled or unshelled in a single layer and cook at 350°F (175°C) for 20–25 minutes in the shell, or 15–20 minutes shelled.
Read More
This post is adapted from a chapter in my second edition of Sustainable Market Farming. The chapter in that book also includes peanut history, information on growing peanuts in a hoophouse, interplanting lettuce and peanuts, solar drying them, and saving seed.
Over-wintered Acadia spinach emerging undamaged from under the ice and snow. Ken Bezilla
Cold winter weather damage to our vegetable crops
Like people and gardens in many parts of the US, we had a very cold February snap. We had at least two nights down to 2°F (-17°C). In December 2025 we had one night at 13°F (-11°C), one at 14°F (-10°C), most were in the 20s. We had one 20°F (-7°C) night in January (1/4-1/5), one at 10°F (-12°C) (1/15-1/16), one at 7°F (1/23-1/24), then two nights at 3°F (-16° C) (1/26-1/27 and 1/30-1/31). In early February we got at least two nights at 2°F (-17°C). Our weather station was the victim of a hit and run, which broke the pole, so we haven’t been consistent at recording our outdoor temperatures. We need the soil to melt before we can dig a new post hole.
Our garlic beds before the snow Feb 2026. The tops can be seen poking through the hay mulch. Photo by Ken BezillaOur garlic beds totally covered in snowcrete February 2026. Ken BezillaOur garlic beds after the thaw Feb 2026. The tops are all still alive! Ken Bezilla
Luckily we had thick snow before it got really cold and the snow froze in place, forming what is now called “snowcrete”. Crops completely covered, like our spinach and garlic, seem to have survived. Ones that had tops out in the air suffered much more. Our Tadorna leeks and our Vates kale don’t look much good, but they are not dead.
Tadorna leeks damaged by exposure to cold weather Feb 2026 Pam DawlingVates kale exposed to cold above the snow Feb 2026 Pam Dawling
I keep records of how well our crops do in winter, both outdoors and in our double-layer hoophouse. I record this as Winter-Kill Temperatures of Cold-Hardy Crops, and I note each increasingly cold minimum temperature and when the various crops die of cold, to fine-tune our planning for next year.
We are in zone 7a, with an average annual minimum temperature of 0-5°F (-18°C to -15°C). According to https://weatherspark.com our temperature is rarely below 15°F (-9.5°C). Here’s screenshot from their site for Winter 2025-2026 so far.
The winter of 2024-2025 was fairly average in temperature
The winter of 2023-2024 was more like the average temperature, with extra precipitation in December and January.
The winter of 2022-2023 included a spell with a deep dive in temperature in late December, and again a cold March. Precipitation was fairly even.
Reflect spinach in the open got damaged but not killed at -9°F (-23°C), in a previous year Photo Pam Dawling
The winter of 2021-2022 was colder than the 90th percentile average several nights each month, particularly in November and April, meaning it felt like a long winter.
The winter 2020-2021 was mild, with our lowest temperature being a single late January night at 10°F (-12°C). We had one night at 11°F (-12°C) one at 17°F (-8°C), three at 18°F (-8°C also) and one at 19°F (-7°C). Very little snow or ice, similar to temperatures in the 2019-2020winter.
The winter of 2018-2019 had lowest temperatures of 6°F (-14°C) in late January 2019, 8°F (-13°C) in December 2018 and a couple of 11°F (-12°C). In early January 2018, we had some extremely cold temperatures of -8°F and -9°F (-22°C and -23°C). Our Vates kale got freeze-killed centers. Averaging our winter low over the four winters 2017-2021 gave 4.8°F (-15°C), within the zone 7a range.
Posts on aspects of winter growing, to help you be better prepared next winter!
Winter Preparations for Vegetable Gardens, includes an article Autumn’s first frost is falling later. For farmers, the consequences are wide-ranging by Sarah Vogelsong, November 3, 2020 from the Virginia Mercury.
Growing vegetables in a winter hoophouse
Lettuce in our hoophouse in winter. Pam Dawling
No crops died in our double-layer hoophouse, where we spread inner rowcovers when the outdoor night temperature is forecast to be 8°F (-13°C). We did get some cold damage to lettuce stems and chard stems but not much, considering.
Another aspect of early spring in our hoophouse, is bolting of the overwintered greens. See Success with Asian Greens in Spring. In spring the order of bolting of some Asian greens is: tatsoi, Maruba Santoh, Tokyo bekana, Koji, Napa cabbage, pak choy, Yukina Savoy, Komatsuna, mizuna, leaf radish, senposai. I wouldn’t even try sowing tatsoi after the winter solstice. Yesterday (2/17/26) I was researching bolting in order to find something to sow in some short-term open space we have. From memory I wasn’t sure which of Yukina Savoy and senposai bolted first, so I counted bolting plants in the plots which were sown on the same day. Yukina Savoy had 15 bolters among 67 plants (22%). Senposai had 9 bolters among 220 plants (4%). Then I considered that the senposai grow enormous quickly and I was sowing in the outer thirds of beds that would be interplanted with tomatoes, squash or cucumbers transplanted down the middle on March 15 or April 1. The shorter, smaller Yukina Savoy was my choice. We can eat the thinnings small in salads, and then harvest larger leaves as the plants grow bigger. In milder weather, it takes 21 days to baby size and 45 days to full size. I’m hoping we’re moving into milder weather now!
I’m prompted to write this post to alert growers to the publication of the revised USDA Plant Hardiness Zone Map (often incorrectly called the Cold-Hardiness Zone Map). Canada and Mexico are now included. Most areas are a quarter-zone warmer in winter than in 2012.
Click this link for more on the history of the USDA Plant Hardiness Map. Note that the original intention of this map, which shows the average annual minimum winter temperature, was to indicate which perennial plants (such as fruit trees or shrubs) would survive the winter in each location. It does also indicate which biennial and annual plants can successfully overwinter (on average). There are lots of things it was never designed for, such as indicating how long the winter lasts, or how many days will be below a certain temperature. It is very valuable for its purpose: showing which plants will survive in an average winter.
Zones 10 and 11 were added in 2012, and Zones 12 and 13 are added to the new 2023 map. Zones 12 and 13 are presently only found in Hawaii and Puerto Rico, where the average annual minimum temperatures are above 50°F (10°C) and 60°F (15°C) respectively. The new interactive map has closer definition between neighboring areas than previously, and can be examined at a finer scale. A city or town with heat-absorbing concrete, can be seen as warmer than surrounding countryside.
Comparison of plant hardiness zones mapped for the 11 largest Metropolitan Statistical Areas [MSAs (U.S. Census Bureau, 2003)] in the 1960, 1990, and recently revised Plant Hardiness Zone Maps.
This technical article by Widrlechner and others in HortTechnology in 2012 gives a short history of the Map, and explains how it can be used to predict winter-injury to plants, and avoid damage by changing shipment dates or adding plant protection. It explains how freeze injury can occur during three stages in the annual cycle of plants: firstly, extreme cold occurring during the fall, before plants have adapted to such temperature levels; secondly, during mid-winter when extreme cold can still overwhelm the plants’ adaptive survival mechanisms; thirdly, during late winter and early spring of plants “deharden” after satisfying their minimum physiological rest requirements, in unseasonably warm spells.
The article also discusses attempts in various regions to add in the effects of other weather features such as cloud cover, wind speed and snow cover. It also discusses the 1997 AHS heat zone map, and shows graphs correlating the Plant Hardiness Zone Map and the Heat Zone Map for three parts of the US. Note the date of publication: references to the “updated” map refer to the 2012 version, not 2023.
Pablo Batavian lettuce. The batavians are our most bolt-resistant heat-tolerant lettuces. Photo Nina Gentle
For summer weather, the American Horticultural Society in 1997 created a Heat Zone Map to show how many summer days are likely to exceed a certain temperature. It is not the mirror image of the USDA Plant Hardiness Map – it does not show the yearly average hottest temperature. I think an update of a heat zone map is due!
AHS Heat Zone Map 1997
According to the AHS map, I am in Zone 7 for summer temperatures (61-90 days a year reaching 86°F (30°C) or more) — right in the middle of the range. According to Weatherspark.com, from June 11 to August 30, our average daily high temperature is 86°F (30°C) or more. Summer nighttime temperatures are also an important feature of the weather, for us and our crops.
Twin Oaks is in USDA Plant Hardiness Zone 7a. (our zone remains unchanged after the November 2023 update, but we did move 5 Fahrenheit degrees milder from our 1990’s 6b to 7a in the 2012 revision). The average annual minimum winter temperature in zone 7a is 0°F–5°F (–18°C to –15°C). I have noticed that our local climate has changed on average, over the past ten-twenty years, to become drier, with milder winters and hotter summer nights.
Savoy cabbage with frost. Photo Lori Katz
Here are other features of our weather at Twin Oaks, Louisa, central Virginia:
Our average rainfall for a year is 37″ (100 cm), fairly evenly distributed throughout the year, at 2.2″–3.6″(5.6-9.1 cm) per month. February is the driest, May the wettest.
Our average daily maximum temperatures are 49°F (9.4°C) in December and January, 89°F (31.7°C) in July. The average night low temperatures are 29°F (–1.7°C) in January, 69°F (20.5°C) in July.
Our season from last frost to first frost is around 211 days. The average date of the last spring frost is April 24 (later than May 7 only happens one year in ten); the average date of the first fall frost is Oct 14 (earlier than Oct 1 only happens one year in ten).
Such grey weather! But will it rain? Photo Wren Vile
Our climate is controlled by three weather systems, mainly by moisture from the Gulf of Mexico, but also by the Bermuda High Pressure area in summer and the recurrent waves of cold Canadian air in winter. Due to the erratic movement of thunderstorms, some parts of our area may experience long periods of drought. September–November is the dry season but also the hurricane season.
Our latitude is 38° N, which is very relevant to onion growing and to daylight length.
Our period when daylight length is less than ten hours and little plant growth occurs, lasts from Nov 21 to Jan 21.
Climate Summary from Weatherspark.com
To learn some of your other weather details, see Weatherspark.com.
Cover Crops for November: Winter Rye (with Austrian Winter Peas early in November)
Winter rye headed up. Mow or turn it under very soon! Don’t let it shed seed. Photo Pam Dawling
The first half of November is the last chance to sow winter cover crops in central Virginia
Our average first frost is October 14-20. If yours is later, see my post Cover Crops for October. It is still worthwhile to sow a few cover crops up to three weeks past your average first frost, and I’ll tell you about those, with ideas on what to do if your climate is past that point.
If the area is ready for cover crops up to 10 days past the frost date, sow winter wheat or winter rye and hairy vetch or Austrian winter peas.
See Planning Winter Cover Crops, a post that includes my Short Simple Guide to Winter Cover Crops and my slideshow Cover Crops for Vegetable Growers.
Last Chance Cover Crops in November: Rye
Rye grows impressive roots that improve the soil. Kauffman Seeds
Winter rye can still be sown in the mid-Atlantic in the first half of November. Winter rye is the cereal grain rye, not ryegrass. Ryegrass comes in annual and perennial forms, but neither is a good winter cover crop here. They don’t produce as much biomass as cereal rye, and can become weeds in our climate.
Winter rye is hardier than any other cover crop and can take later planting dates. Some people do sow winter wheat in early November rather than winter rye, so if you don’t have rye seed, use wheat. It can be tricky to have the cover crop seed you want, without risking buying more than you need. Sometimes it pays to use what you already have, as it may not give good germination if saved over to next fall.
Winter rye has an allelopathic effect (inhibition of germination) on small seeds, that lasts three weeks or more after rye is turned under. This means you will need to be fairly confident that the weather will allow you to till the rye in with three weeks to go before sowing carrots, spinach or other spring crops with small seeds. Transplants are not affected in the same way. If necessary, reconfigure your crop rotation plan over the winter. Plan for the next food crops after winter rye to be ones planted after late April, such as late corn plantings, winter squash, transplanted watermelon, sweet potatoes, tomatoes, peppers, June-planted potatoes, fall brassicas, and second plantings of summer squash, cucumbers, beans.
A field of winter rye with a strip of crimson clover in early May. Photo Bridget Aleshire
Adds lots of organic matter if grown to full size.
Improves the soil’s ability to absorb and store water.
The roots hold the soil together and greatly reduce erosion.
Can be used to scavenge nutrients left over from a previous legume crop or to hold onto nutrients applied for a crop that failed.
Sow from 14 days before to 28 days after first fall frost.
Don’t sow before September in zone 7 – it may set seed.
Rye makes little growth in mid-winter, but very good growth once spring arrives.
Rye can be sown in the spring, although when incorporated, oats break down quicker.
Can be undersown in sweet corn or in fall brassicas in early September, and left as a winter cover crop.
Cover crop of rye and winter peas with flowering crimson clover. Photo Bridget Aleshire.
Include Austrian Winter Peas if possible in the first week of November
See my September post for more about the benefits of including legumes with winter cover crops grasses. Also how to inoculate legume seeds with the nitrogen-fixing bacteria. Austrian winter peas can be sown later than other legumes. See my October post for more about those. See Working with the time you have left for options if you are in another climate zone.
A key to success with legumes is to sow early enough in fall to establish before winter halts growth, and to plan not to need that plot next year until flowering time for that legume. Austrian winter peas bloom here at the end of April (about a week later than crimson clover, and a week earlier than hairy vetch). (If you have a legume that doesn’t reach flowering, you get less nitrogen for your money, and will need to add some compost or other source for the following food crop.) Suitable crops for following Austrian winter peas are ones planted after May 1: winter squash, melons, sweet potatoes, tomatoes, peppers, middle sowings of sweet corn, June-planted potatoes. This is pretty much the same list as crops that can be planted after winter rye.
Austrian winter peas Photo https://www.uaex.edu
October 15 (our average frost date) is our clover/peas watershed (legume-shed?). Before that date we use crimson clover; after it (until 11/8, 3 weeks after our average frost date) we sow Austrian Winter Peas, along with winter rye or winter wheat.
Austrian winter peas winter-kill in zone 6, but are hardy in zone 7. Hardy to 0°F (-18°C). Sow Austrian winter peas at least 35 days before first hard freeze (25°F/-4°C) – in zone 7, that’s a 50% chance on 11/8. See Weatherspark.com for info on your location, or Dave’s Garden.
Last Chance cover crop
In the second week of November, we sow winter rye alone as our last chance cover crop. It is too late for any legumes.
Grain seed will store OK for the next year, but peas and beans really lose viability fast. If you still have Austrian winter pea seed from last year, I’d say throw it in this November rather than keep it for a third year, even if you are past the usual date. Germination rate goes down to 50% after a couple of years, and the plants won’t be sturdy.
Barbara Pleasant tells us two other ways cover crops can improve soil: Rhizodeposition and bio-drilling.
Rhizodeposition is a process whereby plants release sugars and other substances through their roots. The root tips host colonies of helpful microorganisms that go deeper as the roots grow deeper. For rye, this depth can reach 6 feet (2 m)!
Bio-drilling is what happens when cover crop roots “drill” into compacted subsoil. Oilseed and daikon radishes are cover crops famous for this action. The roots push deep into tight subsoil. Bio-drilling also happens when deeply rooted cover crops penetrate the subsoil and then die. With winter rye this can happen when the headed-up rye is mowed close to the ground in spring, or the rye is tilled into the top soil, severing the roots below till level. The next crop can follow the root channels made by the cover crop. This gives access to nutrients (including dead roots and microbes) left behind by the cover crop.
How to protect the soil over the winter if it is too late for cover crops
Carrot harvest cart. Our Danvers carrots have plenty of sturdy leaves to protect the soil over winter. Photo Mari Korsbrekke
Sowing cover crops too late means you don’t get enough growth in the fall, and the soil is not adequately protected from erosion or from weed growth over the winter. Try really hard not to leave bare soil over the winter.
If it’s too late to sow cover crops, but you do have a healthy growth of weeds, mow them at the beginning of November and then leave everything alone until early spring. The weed roots will hold the soil together and the above-ground growth will protect the soil from heavy rain. Having live plants will provide food for the microbial life in the soil.
If you don’t have weeds, but only almost bare soil, and it’s too late to sow cover crops, find some kind of organic mulch to cover the soil. When we harvest our storage carrots in November, we return the cut tops to the soil surface. Another seasonal option is tree leaves (sometimes conveniently left in bags by the curb). Best to ask the “owners” before lifting them. Other ideas include straw or hay. Woodchips or sawdust will work for winter protection, but don’t till them in when spring arrives. Rake them off and compost them nearby. If turned under, they use up a lot of nitrogen decomposing, and your crops will be starved.
More resources on cover crops
My book Sustainable Market Farming has a chapter on cover crops and many pages of charts about particular options.
Cover of Managing Cover Crops Profitably book from SARE
The book Managing Cover Crops Profitably (third edition) from the Sustainable Agriculture Research & Education Program (SARE), is the best book I know on the subject. You buy the book for $19 or download it as a free PDF from SARE.
The January issue of Growing for Market is out, and in it is my article More strategies for dealing with a changing climate. A photo of our fava beans is on the cover. This is the third in a series of four. (You can see earlier blog posts about the first two, in the Articles category.) This article covers the use of soil temperature as a deciding factor on when to sow or plant, and includes a table of minimum (spring) and maximum (summer/fall) temperatures for about 50 crops. As the climate becomes harder to predict, using a calendar (“Plant potatoes on St Patrick’s Day!”) will need to be replaced by using information like soil temperatures, which reflect what the plants will actually experience this particular year.
The article also discusses scouting, which is the practice of making a regular tour of your crops to monitor growth and health. If you see a pest or a disease, you can determine if the level of infestation is enough to call for action, or if watchful waiting is in order. Keeping in touch with how your crops are doing will help you know when you need to take action to avert disaster or to make good use of an opportunity like an early-finishing crop opening up the possibility of using a longer-term cover crop.
I also talk a bit about being prepared for more extreme temperatures – trialing varieties that are more cold- or heat-tolerant than your old favorites, and using shadecloth and organic mulches to reduce heat stress. ATTRA’s Drought Resistant Soiladdresses ways to increase the organic matter content of the soil, and keep the soil covered at all times, helping you farms’ resilience.
In addition I added in a few more resources I’ve found to help with predicting climate change. DailyClimate.org – a daily email newsletter; NOAA Climate Prediction Center, and Weatherspark.com, a fun weather site is where you can see, for instance, what your average winter low has been, and plan plantings accordingly.
Why the fava bean photo? Wait till the soil temperature reaches 36F (2C) before sowing.
As well as my article, there are many other gems – Identify your biggest money-making crops by Chris Blanchard; A Tool Review of The Quick Cut Greens Harvester by Jean-Martin Fortier; 8,000 miles and 18 farmers markets, a travelogue by Gwynn Hamilton and Bert Webster about their cross-country road trip visiting farmers markets all the way; Understanding one of the few insecticides for organic growers by Raymond A. Cloyd, about spinosad formulated as Entrust, and Growers create their own wholesale market for local flowers in Seattle by Debra Prinzing, co-author ofThe 50-Mile Bouquet about the movement toward locally grown, sustainable flowers.
I also talk a bit about being prepared for more extreme temperatures – trialing varieties that are more cold- or heat-tolerant than your old favorites, and using shadecloth and organic mulches to reduce heat stress. 
Why the fava bean photo? Wait till the soil temperature reaches 36F (2C) before sowing.