Fall Fun on the Roof

Autumn winds have blown into DC and we’ve been getting the Georgetown Rooftop Food Project ready for cool weather. Aside from gorgeous views like this one:

there are the regular fall garden tasks to check off the list. First things first—getting a new round of cold-hardy crops planted. On October 1 we sowed seeds for Encore lettuce mix, Ovation greens mix, Minutina, Mei Qing pac choi, Mokum carrots, Merlin beets, Hakurei turnips, and three kinds of radishes (Miyashige, Red Meat, and Easter Egg). Now, a few weeks later, we have cute ruffly rows of baby greens and root crops.

Another fall job is saving seeds to squirrel away for next year’s plantings. Sunflower seeds are easy—you just pry seeds out of the dried up flower head and pick off the husks.

Tomato seeds take a few more steps. After scooping the seeds into a bowl, you have to let them ferment for a few days until moldy, then rinse several times in clean water, which washes away the poorer quality seeds and leaves the viable ones. Good step by step instructions for saving tomato seeds can be found here.

With tomato production winding down and first frost on the way, it’s time to clear spent vines and sow cover crops! It’s fun to cast handfuls of winter rye, hairy vetch, and spurs oats seeds across the cleaned up beds. These cold-hardy cover crops will protect the soil from wind and rain and help build nutrient levels for next season. This site gives some good pointers on maintaining soil fertility in raised beds.

And to help with autumn clean up, we assembled two new compost bins so we can turn our garden “waste” into a nutrient goldmine right on the roof!

Back-to-School Buckwheat

Back to school, in the garden! Three weeks ago, we decided to sow a cover crop of buckwheat in an area of the garden where we had grown potatoes. Cover crops can have several positive impacts on the organic garden system. First, cover crops add biomass and build organic matter in the soils, breaking up clay soils and making more nutrients available to crops that follow. Some cover crops, like legumes and clovers, fix nitrogen from the air into the soil, working cooperatively with soil bacteria to do so. Cover crops can outgrow and smother weeds (especially buckwheat, which has to be the fasting growing non-weed we’ve ever seen!), and can also facilitate the disruption of pest and disease cycles in the garden. Cover crops tend to have a ‘mellowing’ effect on the soil, and also protect soil from erosion & the elements.

Point is, cover crops are cool. Problem is, many of us organic gardeners know that cover crops are a good thing, yet can never seem to get around to actually sowing them in our garden. The two main barriers to a lack of cover crops in the organic garden are space & seed. Unless you live in the outerburbs, many garden centers do not carry cover crop seed. And unless you have a large garden, it may seem like a waste of space to put a section of the garden in cover crop.

The key to using cover crops begins with having a stockpile of cover crop seed on hand. Most garden catalogues carry cover crop seed in small enough increments to use over the course of a couple years in the backyard. Four good cover crops to have in your closet are: buckwheat, oats, winter-rye, and white clover. If you have an area that is ‘spent’, like an early planting of squash, and are not about to do a second planting, just get out there and broadcast some of your cover crop seed. It’s fun, and makes you feel like a wise gardener. Buckwheat is a fast-growing summer cover crop, but does not do well in the cold. When the frost kills your tomatoes, you still might be able to sow a cold-hardy cover like winter-rye. Each cover crop has its purpose and place in the organic garden system.

Now that you have the seed, you might find yourself with a space problem, particularly in the urban garden. The space problem can be solved through the technique of undersowing, or getting cover crops started a few weeks before a particular vegetable crop is done, right underneath the vegetables, in the same bed. For instance, now’s a great time to ‘undersow’ your tomatoes with oats. The oats germinate, grow up a few inches, then the tomatoes die back, and the oats can carry on into the fall before eventually dying after several hard frosts. Eliot Coleman, the Maine organic farmer and author, writes extensively about undersowing cover crops in his book, The New Organic Grower.

Once you get started with cover crops, you won’t want to stop. Buckwheat is a great one to start with, and you can probably still sow it this week, giving you a few weeks of growth before the first killing frost…

Cover crops for new growing space

Spreading straw over cover crop seeds
Originally uploaded by Local Food Project at Airlie

We’re expanding the current layout of the Local Food Project garden to include at least two new sections on the west side. This area is currently outside the fence, but we’ll be replacing the fence line this winter to include our new sections (along with extra room for future growth).

To begin preparing the soil for next spring, we made one pass with the tiller about four weeks ago. Last week, we tilled again, then direct sowed field peas and oats by scooping them out in handfuls and letting them scatter over the freshly turned soil. These cover crops, also known as "green manures," do great things for the soil. According to Eliot Coleman's The New Organic Grower, "Green manure crops help protect against erosion, retain nutrients that might otherwise be leached from the soil, suppress the germination and growth of weeds, cycle nutrients from the lower to the upper layers of the soil, and--in the case of legumes--leave to the following crop a considerable quantity of nitrogen."

The little seeds that ran through our fingers will bring enormous benefits to our garden! To keep them protected, we fought high winds and covered each section with a light layer of straw. When we’re ready to put seedlings in the ground next season, we’ll plant directly through the cover crops, then watch as the plants thrive in the enriched soil.