I’m a huge fan of risky behavior in the garden. The edge is where the action is. Our seasonal weather in Utah is a wild ride to be sure, and you never quite know what the next week will bring. A boss level gardener strives to bring in a harvest in all eight seasons, but this is no easy feat here in our high-altitude steppe climate (yes, I track eight seasons a year, but that’s a story for another day….)
Perhaps I’m willing to take so many risks because I have plenty of tricks up my sleeve for manipulating the microclimates my plants inhabit. As we say at the OchO, “Safety doesn’t have to be your first priority but it damn well better be in the top three.”
When most of us think of season extension, we think of cold frames, greenhouses and other techniques for making things warmer in the cool months. This is a fantastic way to get early crops of lettuce and other leafy greens in the spring. Or perhaps, we think of using the these techniques to extend our harvest into, and even over, winter. This strategy can double or even triple your garden output. If you aren’t already doing this in the spring and fall, then hop on the Boss train and level up.
Bring on the heavies
Let’s take it one step further. Creating warmth in cool months by capturing the power of the sun is simple and straightforward. Simulating cool weather in the brutal dry heat of a Utah summer is much more difficult.
What’s the point? Who in the hell is even thinking about fall gardening in July, when most of us haven’t even gotten our first tomato or cucumber yet? (Not this guy; I acknowledge bragging is tacky, but also want to state for the record that I was harvesting tomatoes, cucumbers, and zucchini by June 15 this year. And no, not with some tacky “Early Girl” tomato bullshit. We’re talking real tomatoes, a Japanese variety, “Sakura.”)
The point? Broccoli, cauliflower, cabbage, the “heavies” in the garden in fall. I love my greens, but my kitchen also appreciates some density in the wok once the zucchini and peppers have faded from memory. And with their long DTM, it takes some early work to pull off a successful crop. DTM: days to maturity. This is the number of days from when a seed is planted until the vegetable is harvested.
Now it’s time to speak the eternal language of the universe: mathematics.
Do the math
Most full, thick, delicious heads of broccoli have a DTM of 60-70 days. Most types of cabbage take at least this long as well; some take much longer. Now, we can cheat and grow faster varieties, but these tend to be much smaller; and let’s be honest, size does matter.
Scenario #1: Get an early jump on fall
Fall in the northern hemisphere begins September 22, and we want to get a head start on the “heavies” above. We plant on September 1, when the hot, dry Utah summer finally breaks. At 65 DTM, we can run some simple math and expect a harvest on November 4. Excellent, nice work, high five! Well, not so fast….
The “days to maturity” number assumes growing in ideal conditions, midseason, when the days are much longer. As daylength shortens, the time it takes to grow a vegetable lengthens, as the plant is able to gather less and less sunlight energy each day in the fall. We must now add an additional 20-30% to our DTM to accommodate for decreasing day length.
Our 65-DTM broccoli has now become an 85-day broccoli, pushing our harvest out to November 24. No worries though, right, as that’s just in time for Thanksgiving! But…I need to rain on your parade once more.
On November 12, we will cross below a critical day length threshold. At nine hours, 59 minutes and 54 seconds, we fall below the 10 hours of sunlight that vegetables need to grow. Stuck in a time warp, they are unable to gather sufficient sunlight energy. While taking advantage of this can be a useful trick for extending your harvest window, unfortunately we will have not matured our head of broccoli, cauliflower or cabbage. In fact, as we approach this date, our plants become less vigorous, an open invitation to aphids and other pests. Fail.
Scenario #2: Get started in summer
With the above math in hand, let’s assume an adjusted DTM of 85 days for our “heavy” fall crops. Let’s also aim to have them finished by the mid-October, so we can take advantage of some secondary floret creation in our broccoli and cauliflower. For a harvest date of October 15, we must start seeds August 1. And for you, dear reader, that means you need to gather your seeds, soil and supplies this month.
The easy method: Start your plants indoors. All fall crops germinate and appreciate growing at the same temperature as a climate controlled human residence. No need for heat mats—it’s much easier than starting heat-loving crops in the spring. Transplant sturdy seedlings outside in September, four weeks after germination. For all the info you need on starting seeds indoors, read my very first article written for CATALYST here: [https://catalystmagazine.net/from-seed/]
The “let’s get crazy” method: Let’s do this outside. What hoops and plastic are to spring, shade cloth and misters are to summer. To grow cool weather crops in summer, one must drop the temperature and raise the humidity. The most straightforward approach is with shade cloth and misters.
Choose a spot in your garden that gets ample morning sun, full midday sun, and afternoon shade. If you are starting plants in pots, make sure they are elevated off the ground; I prefer pallets, staked three-high. This ensures air flow and helps keep soil temperatures down, and deters pests such as earwigs who will take full advantage of tight, dark, moist spaces such as pots sitting directly on the soil.
Next, erect hoops over your growing area, as if you were building a low tunnel. Cover this with 30-40% shade cloth. (I prefer using white. Black will also work, and is the easiest to find, but white has a much lower radiant heat transfer.) The 30-40% shade will lower the temperature substantially, yet also provide plenty of light to grow healthy plants.
Finally, install an appropriately sized patio misting system to the underside of the hoops, beneath the shade cloth. Connect this to a faucet with a timer. I run mine for 20 minutes, three times a day; 11 am, 2pm and 5pm. This further drops the temperature, raises the humidity, and has the added benefit of irrigating the seedlings at the same time.
This season, my fellow gardener, is your time to master the elusive “heavies” of the fall garden. I commend you in advance.
James Loomis is a full-time urban farmer, educator and keeper of the Old Cherry Orachard (aka OchO), a permaculture farm. He lives in Salt Lake City.