Rural Studio Farm

Soil Blocking, or Making Soil Brownies

Students always call them soil brownies, and they do look tasty!

Soil blocking, which was developed in Europe and largely popularized in the US by legendary organic farmer, Elliot Coleman, is a practice of starting seedlings in cubes of compressed soil. While Rural Studio Farm still makes use of plastic flats for starting seeds of certain crops, soil blocks eliminate the waste and expense of using plastic containers.

The blocks are made in metal molds from a mixture of soil made here on site at Rural Studio Farm, which makes them more labor-intensive to begin with—and thus might not be suitable for larger scale farms.

However, farm manager Eric has found that, overall, seeds tend to germinate and grow better in blocks, and transplanting soil blocks into the field is faster and easier than having to remove each individual seedling from its tray.

Throughout the past two weeks, tomatoes, eggplants, and peppers that were started in 2-inch soil blocks were upgraded to 4-inch blocks to allow the roots to continue to develop before being transplanted to the field once the soil has warmed up more. The 4-inch mold is made with a 2-inch cavity to accommodate such an upgrade.

There are other advantages to soil blocks. As the growing roots reach the edge of a block, they stop growing in what is called “air pruning,” as opposed to wrapping themselves about as they would in a conventional pot or cell. Indeed, as the blocks are transplanted directly into the ground, root disturbance is almost entirely eliminated, meaning that more delicate plants that cannot tolerate root disturbance can be started this way.

Don’t Rebuke the Cuke

Loads of mature cucumbers hang from the trellised plants in the greenhouse

Like tomatoes, cucumbers are well suited to being grown in a greenhouse where warmer temperatures and the support of vertical growth can produce huge harvests. Eric Ball (Rural Studio’s farm manager) and the students constructed a trellis and began cucumber seeds back at the beginning of March and now their efforts are bearing fruit.

As the cucumber plants grow, Eric pruned off the side shoots so that each plant had a single growing stem, and he helped train the tendrils to grab the trellis. This reduces crowding, promotes good cucumber health and production, and improves ventilation.

Each leaf node produces a side shoot, a flower, and a tendril for climbing.

Until advances in plant breeding, cucumbers were typically monoecious, which means that each individual plant produces both male and female flowers. This also means that they are in need of a pollinator to transfer pollen from the male flower’s stamen to the female flower’s stigma (this can occur on flowers from the same plant). Since these cucumbers are being grown in a greenhouse, where pollinators are infrequent visitors, this means that ordinary cucumbers won’t set fruit unless hand-pollinated—a laborious and time-consuming activity for these productive and delicate-flowered plants.

As such, Eric selected a hybrid cucumber variety that is both parthenocarpic, meaning that fruit can develop without being fertilized, and gynoecious, meaning it produces primarily female flowers, since the redundant male flowers would only divert the plant’s limited resources away from fruit production.

Crop Cycles

This week was marked with large harvests, which were the endings of some spring crop cycles, and seed starting in the seed house, the beginning of new crop cycles.

A close-up of harvested and washed carrots, both purple and orange

Thankfully, teaching faculty, Mary English, Steve Long, Emily McGlohn, and Xavier Vendrell all graciously volunteered their time to help farm manager Eric during this busy period.

Harvested spring crops included lettuces, carrots, collard greens, kale, cutting celery, turnips, arugula, beets, and scallions, as well as herbs like spearmint, dill, thyme, and oregano. Many of these commodities were eaten fresh, but the rest were given to the kitchen where chef Cat processed and stored large quantities for future meals once students have returned.

At the same time, Eric and Emily started seeds for late spring and summer. These future crops were zucchini and summer squash, determinate tomatoes for the field, eggplants, red and orange bell peppers, spicy peppers, and butternut squash.

Eric also planted seeds for various beneficial insect-attracting flowering plants, culinary and medicinal herbs, and perennial ornamentals. While many of these accessory plants do not yield tangible crops, they do confer other benefits on the farm, such as bringing pollinators, deterring pest insects, and aesthetic compensation. It is also a key feature of Rural Studio Farm to use a polyculture model, planting a wide diversity of different crops and flowering plants.

Greenhouse Tomatoes

Nothing says summer quite like fresh tomatoes. However, because of Rural Studio Farm’s greenhouse, our tomatoes are already setting fruit in early April from tomatoes that students started at the end of January.

But growing tomatoes in a greenhouse is a little different than in the field. For one thing, there is less space for such sprawling, vining plants to grow. So in the greenhouse, students take advantage of vertical growth by supporting the growing tomatoes with strings dropped from a support line. Then students pruned the plants down to a single growing stem.

Tomato plants produce suckers at the nodes between stem and branch (coming off at about a 45-degree angle) that will eventually grow into separate stems, each producing its own branches and fruit, and students prune these off, sometimes daily once growth takes off. Such pruning produces fewer tomatoes overall, but these tomatoes are larger and more plants can be packed closer together, producing a higher total yield. Students also removed all branches below the first fruit cluster to open up air movement around the disease-prone plants, especially since airflow is limited in the greenhouse.

Since our farm manager Eric is working solo right now, he also started some smaller determinate tomatoes, which max out at five feet tall, in an effort to try and minimize such high-need practices, since determinate tomatoes require less support and only very minimal sucker pruning (only below the first flower cluster) or else yields are reduced.

Potatoes, Potahtoes

A wide view of potato plants, collards, and cover crops

Most potatoes are not grown from seed, but rather by planting out “seed potatoes,” which are just high-quality whole potatoes, or pieces of potatoes, that were saved from a previous season. Here in Alabama, February is the best month to plant them, which is what Eric and the students did, despite all the rain. There are many ways to plant out potatoes, but at Rural Studio Farm the students set them out along shallow trenches in the newly built in-ground raised beds.

Then, students covered the potatoes with several inches of hay (many growers hill up soil around the seed potatoes). The hay protects the potatoes, modulates temperatures, suppresses weeds, and helps to retain moisture.

After a few weeks, the potatoes pushed their way through the hay and continued to grow.

Once the sprouts reached about 8 – 12 inches, Eric then hilled up even more hay around the plants until only the growing tips were left exposed. As the potatoes grow, the tubers will form in the hilled-up hay, increasing yields. This also eliminates the need to do any digging to harvest the potatoes—just open up the hay.