Radishes make a great cover crop for your vegetable garden, adding nutrients and eliminating the need to till.

Of all I saw, heard and learned during the long day I spent wandering semi-aimlessly around the sprawling Maine Agriculture Trades Show at the Augusta Civic Center earlier this month, that’s the information that stood out.

Cover crops help prevent erosion as well as improving the soil. In the 40 years my wife and I have been tending our 50-by-50-foot vegetable garden, I’ve been intrigued by these cover crop benefits, but figured that growing winter rye or oats and killing them off at spring planting time would be labor intensive.

Frankly, I’m not ready for more work at the end of a growing season. But now, having learned about radishes, I’m re-evaluating.

Natalie Lounsbury, who recently received a master’s in soil science from the University of Maryland and farms with her mother at River Rise Farm in Turner, told a packed session sponsored by the Maine Organic Farmers and Gardeners Association (MOFGA) that radishes have many advantages over other cover crops.

Now, don’t picture the crisp, tender and tasty French Breakfast radish that gives spring a colorful start. Radishes used as a cover crop are forage radishes; in the Fedco catalog, they are located in the Organic Growers Supply section, not the seed section.

Where radishes have the advantage is their sensitivity to the cold. Three consecutive nights of temperatures in the 20s, and they’re history. Over the winter, many of the dead radishes are pushed out of the ground, where they decompose, adding organic material to the soil.

But it is the radishes’ tiny tap roots that do the most good, drilling into the soil, “as much as 7 feet in some cases, creating a root channel,” Lounsbury said. “Your vegetables aren’t stupid. They know the root channels are there, and they find them.” The roots follow those channels and reach more nutrients.

Rain also follows the channels, going deeper into the soil. The tap roots loosen hard-packed soil and mix up the nitrogen left in the soil, making it more accessible to the vegetables and reducing the need for farmers to use expensive fertilizer.

Maine gardeners and farmers should plant forage radishes at a quarter to half pound per 1,000 square feet, and they should do so in early August. The date is Lounsbury’s best guess, as she did her research in Maryland, not Maine.

Once the seeds sprout, the radish tops prevent weeds from sprouting by shading them out.

In spring, the garden is ready for planting, even with the tiniest carrot seeds (or other early spring crops, including spinach, beets, lettuce and peas), without tilling – which she and many other organic farmers believe compacts soil and destroys its structure. She displayed detailed research showing better performance by most plants where radishes were used, compared to other cover crops and no cover crops.

Two caveats. First, radishes are brassicas – which I hadn’t realized because in catalogs they aren’t lumped with the cabbage and Brussels sprouts.

The point is: Don’t plant brassicas in the areas where you use radishes as cover crops, because if pests attacked the radishes, they’ll get your brassicas, too. Speaking of which, plant the cover crops only every two or three years, because brassicas attract a lot of pests.

Find more information at notill veggies.org.

BEWARE OF SPOTTED LANTERNFLY

The Maine Department of Agriculture has a new insect pest to worry about, namely the spotted lanternfly. The 1-inch wide insect has been found in Pennsylvania. That’s still a ways from Maine, so why worry? Because they hitch rides on vehicles and in other ways, and quickly, explained Karen Coluzzi, who was staffing the department’s Maine Bug Watch booth at the agriculture show.

The insect has spotted wings, and the back wings are scarlet.

Though it prefers to breed on the tree of heaven (aka Chinese sumac), it will attack many other trees, including apples, plums, cherries, pine, grapes, oaks and poplars, and it could damage orchards and other agriculture, according to a U.S. Department of Agriculture (USDA) fact sheet.

MAINERS HIGH ON CSAS

The Maine Sustainable Agriculture Society (mesas.org), which promotes profitable year-round agriculture in Maine, presented a lot of information on using energy-efficient greenhouses, be they insulated, solar-powered and/or with heat pumps.

During one presentation, USDA statistician Gary Keough presented a mind-numbing amount of data, but one statistic stood out: Waldo County has the sixth highest percentage of crops sold through community supported agriculture (CSA) shares in the country, and two other Maine counties were in the top 20.

That says something about the state of CSAs in Maine.

HOPS POPULAR BUT NOT EASY

Maybe you’ve read about the national hops shortage? Craft brewers need a lot of hops for their beers, but are struggling to buy it. And maybe you’ve daydreamed you could get rich from growing hops.

My advice? Think before you jump.

In a presentation sponsored by MOFGA, Jason Johnston discussed his struggles with downy mildew, irrigation, fertilizing and harvesting. Johnston and his wife, Krista Delahunty, started Aroostook Hops six years ago.

At least they don’t have Japanese beetles. Yet. The pest hasn’t reached Aroostook County.

In southern Maine, however, the beetles hungrily chew away at hops bines (which, unlike vines, grow in a helix around supports). Then there’s the fact that hops growers spend a lot of time and money creating the poles, cables and twine on which the bines grow.

In one area, Aroostook Hops has had unqualified success: it sells all the hops it can grow to Maine brewers.

But when Johnston was asked how long it takes before a grower makes a profit, Delahunty – who was caring for the couple’s two young daughters at the back of the crowded hall – called out, “How about we’ll let you know” when it happens?

Tom Atewell has been writing the Maine Gardener column since 2004. He is a freelance writer gardening in Cape Elizabeth and can be contacted at 767-2297 or at tomatwell@me.com.