Shifting seasons

Tips on preparing your garden for winter — and the next bumper crop

A frost blanket can protect plants in fall.
Photo by Carol O\'Meara

As fall harvests wind down, some backyard gardeners may think the work is at an end. But local agricultural experts agree that there are several steps that should be taken to make next year’s growing season even more bountiful. Or even prolong the current yield.

Recent floods in Boulder County have altered the landscape of crops and gardens — any produce that made contact with floodwater should not be consumed or used for compost. But those with usable crops and those starting more or less from scratch do have options for improving their garden.

Janet Poley, co-owner of Hoot ’n’ Howl Farm, says one chore she and her husband Bob face at the end of the fall harvest is clearing out all of the crops that might carry disease or bugs into the next season.

“Once it freezes, we have a lot of cleanup to do,” Janet Poley says, explaining that they compost the old crop material or spread it over an area where they won’t grow the same crop the next year. She cautions against composting with the same crop unless one has a high-temperature composter, which kills anything that might be carried into the next season.

“We won’t put tomato compost back on a tomato field,” she says.

Carol O’Meara, coordinator of the master gardener program at the Colorado State University Extension-Boulder County, where she is extension agent for horticulture entomology, agrees. But she says crop rotation in a backyard garden simply won’t do the trick when it comes to keeping harmful insects from returning.

“If you have tomatoes or spinach or something like that in one bed, and then the next year you put it over into a different bed that’s four feet away, it’s not going to confuse that bug for very long,” O’Meara says. “It’s not going to circle the bed, saying ‘I know it was here last year!’”

And while plant diseases aren’t as mobile, she recommends pulling all crop material up and destroying anything that might have been afflicted.

“For disease, it is very true, because what you do now in the fall will set your garden up for good health in the spring,” O’Meara says, adding that disease is “a little more restricted in movement to certain things, like splashing water, moving it around on gardener’s gloves, this type of thing. So what I strongly recommend is meticulous garden cleanup.”

Among the most common diseases is early blight on tomato plants, in which the leaves yellow from the bottom with concentric rings.

“That’s the kind of disease you don’t want to compost, because it won’t be destroyed in most backyard compost situations,” she says.

The most likely bug culprits infiltrating gardens along the Front Range include the cucumber beetle, which lays its eggs in the soil; the spinach leaf miner; and the tomato horn worm, which pupates in the earth.

Like Poley, she says most backyard composts don’t get hot enough to kill these intruders. One would need to heat compost to 145 F or above for at least three days, turn it, then heat it for another three days at the same minimum temperature to ensure that bugs and disease are killed off, according to O’Meara.

While some recommend planting a ground cover in the fall, which Poley refers to as “green manure,” and then tilling it into the soil in the spring, she says Hoot ’n’ Howl doesn’t do it because of the time and labor required. Some subscribe to the practice because it enriches the soil by adding nutrients like nitrogen — perhaps even reducing the number of weeds that sprout up the following summer.

“But in general,” Poley says, “my experience is that nothing reduces weeds except good old pulling.”

O’Meara says planting a section of a garden with ground cover can be beneficial, but it can be a challenge for small plots since many crops are still producing during the window of time to plant such cover, mid-September to mid-October.

Popular ground cover candidates in our area include hairy vetch, crimson clover and winter rye, she notes. O’Meara adds that with or without ground cover, a garden should only be tilled once a year, either in fall or spring, because excessive tilling can disrupt beneficial fungi and other microbial communities. Spring tilling should be done about one month before you plant, she says. And according to O’Meara, it doesn’t matter whether you till in fall or spring, unless you are using fresh manure, which needs to sit for at least four months to avoid E. coli.

When asked about covering perennial crops that aren’t being pulled up and composted, Poley recommends covering strawberries with seedless straw.

That’s the only crop they cover with mulch, she says. Other plants that they leave in the ground yearround are certain flowers, like zinnia, because they help prevent wind erosion.

Poley also advises blowing out irrigation lines and dismantling drip tubing, storing them in a covered area where they will be protected from the elements.

“The sun will deteriorate things quickly,” she says. Another end-of-season chore at Hoot ’n’ Howl is to roll up the black woven fabric used as a weed barrier between rows, because the farm reuses it.

She also says some amateur farmers call it quits too early in the fall, when a hoop house or other greenhouse-like structure can extend the growing season a bit.

O’Meara adds that “you can be harvesting into December on that.”

She also advises that, when covering crops like tomato plants, to protect them from freezes, plastic is preferred if precipitation is in store, but a blanket is better if it’s dry. Either way, the material should touch the ground on all sides of the plant.

Poley notes that some crops, like turnips and beets, are not harmed by the first frost.

In fact, O’Meara says certain plants — like kale, parsnips, carrots, spinach and Brussels sprouts — actually sweeten with a frost.

Things like pumpkins and winter squash, however, are a different story.

“Don’t let them get kissed by frost,” O’Meara says.