A little over three weeks ago, I planted some radish and arugula seeds in the ground. With a little more sunshine and rain, those crops will be ready to harvest in a couple of weeks. They were the final seeds put in the garden for consumption in the 2014 growing season. They were not, however, the final seeds to be planted in the garden. In October, I sowed several rounds of cover crops in the garden. These “crops” aren’t meant to be consumed this year, but they serve an equally important role in the garden. Each time I finish harvesting a given crop in the field, any remaining plant material gets mowed down, then tilled shallowly so the debris can break down and rot into the soil. Most of the microorganisms that do the work of breaking down crops live in the top couple of inches of soil, and you certainly don’t want your micro-organisms, plant debris, and loose soil to wash away now that the soil lacks plant roots to keep it in place. Enter cover crops. Cover crops, as they are aptly named, cover the spaces in your garden that have opened up once you are done harvesting. On a huge farm, whole fields may sit in cover crop while others are used for growing crops for consumption, then they are switched back and forth each season. Because my farm is only an acre, I used every available inch to grow crops this year, but I will have cover crops do their work over the winter. Cover crops will survive cold and even frigid weather, and keep soil anchored through rainstorms, wind, and snow melt. In the spring, they will recommence growing and provide luxurious greens that can be mowed and tilled in to build the soil and provide organic fertilizer for the spring edible crops. This year, I have chosen to use a mix of plants to act as my cover crops.
Clover and Austrian Winter Peas are cold hardy legumes, plants that can take nitrogen from the air and fix it into the soil where it can act as a fertilizer. These plants will vine and spread to cover the surface of the ground. In the spring, they will make beautiful blossoms that will attract pollinators to the garden, and the tender tips of the pea plants can be eaten in salads or used in stir fry. Tillage radishes and brown-seeded mustard are both in the Brassica plant family and serve different purposes. Tillage radishes make long, skinny roots which will rot away in the spring and thereby help break up soil compaction and allow air and water percolation through the soil. The brown-seeded mustard plants will make edible greens in the spring, but they will also send up large stalks that will provide vertical structure for the peas to climb. The seed from these plants can be harvested to made spicy brown mustard! Winter rye is the most cold tolerant plant in my cover crop mix, and even if we get another frigid winter this year, it will survive and grow again in the spring to provide lots of biomass that will be cut down and added back to the soil. Over the winter, its deep roots will keep the soil in place. Buckwheat is a plant that is often grown as a summer cover crop because it grows rapidly in the heat and is quite sensitive to cold and frost. I had some buckwheat seed laying around and I sowed it in with my fall cover crops. I know it will die back soon, maybe even tonight with our first freeze, but in the meantime it has grown quickly and is no doubt helping keep the soil in place. It will die off just as the cool-loving crops want more space to spread out. Finally, there are a lot of volunteer cover crops doing their work out in the garden. Some people might call these plants weeds, but I look at them as a free cover crop. Mostly I see henbit or purple dead nettle (I have a hard time telling them apart when they’re little) just starting to leaf out. These are low-growing plants that will act as nurse crops, filling in the spaces between the intentional cover crops. What I’m hoping for this winter is a lush, green carpet to cover the bare soil. In the spring, I look for the green carpet to give rise to a beautiful stand of plants with low growing vines, lots of vertical structure, and flowers aplenty. At the moment, our green cover crop carpet is well underway, and with the rain we have been receiving for the past week, it is glowing and growing before my eyes. These plants are happy to be out in the cool weather and are saying, “bring it on!” to the winter. So am I.
It’s October. I just stopped at a restaurant with a chalkboard menu adorned with fake cobwebs and spiders. Folks are taking cornstalks from the field and bundling them up on their porches to adorn their doorways. Everywhere I look there are big orange pumpkins waiting to be carved into jack-o-lanterns. When I was a kid, I loved carving pumpkins as much as anyone, but now that I’m a farmer, sometimes I look at those huge pumpkins and wonder, “Is bigger really better?” I’m not trying to be the grinch that stole Halloween, but I think about growing vegetables ALL THE TIME, and because jack-o-lanterns are vegetables, I contemplate the cost of growing these huge veggies. I’m not talking the dollars and cents it takes to grow mammoth-sized pumpkins, I’m talking about the cost to the fertility of the garden.
Pumpkins are squash, and they belong to the family Cucurbitaceae along with cucumbers, melons, gourds, and zucchini. All of the cucurbits require a lot of room to grow because they have sprawling vines, and they are heavy feeders, meaning they require soil that is rich in many nutrients. You can think of them as plants with big appetites. Oftentimes, fertilizers, either synthetic or organic, are used to provide extra nutrients for pumpkins and their squash relatives. Most fertilizers include the three big plant nutrients: nitrogen, phosphorus, and potassium. Nitrogen, in particular, promotes rapid growth of plants, which is why plants grow so quickly after the application of nitrogen-heavy fertilizers. Along with big appetites, pumpkins get thirsty, and to grow a prize-winning big pumpkin, you need a lot of water. One source I found quoted 89-134 gallons per day for a 1000 square foot garden. This is especially important if the pumpkin is growing rapidly because of the addition of extra plant nutrients, like nitrogen. So what do all these fertilizers and gallons of water give us? Well, besides an awesomely huge pumpkin to look at, a watery pumpkin. Pumpkins are 85-90% water, so a medium-sized jack-o-lantern pumpkin at 18 lbs is around 15-16 lbs of water and 2-3 pounds of fiber and nutrients. Pumpkins are a good source of beta-carotene, they have a lot of fiber, the seeds are high in zinc, which is great for your immune system, and they contain a lot of vitamins and trace minerals. If you eat your pumpkin, you absorb many of those nutrients in your body, and a short time later, the fiber and metabolites go elsewhere (that’s the polite way of saying that they go down the toilet). If you don’t eat your pumpkin, the nutrients end up in a rotten puddle on your front porch, or maybe splattered on your sidewalk if there are marauding teenagers in your neighborhood. I would almost guarantee, though, that the nutrients don’t go back to the field where the pumpkin grew. Instead, there is now a nutrient “hole” in the garden, leaving fewer nutrients behind where the pumpkin was heavily feeding on water and soil nutrients all season long.
Before you get depressed and swear off jack-o-lanterns forever, there are some ways to grow pumpkins and keep your garden healthy instead of depleting it of nutrients. First, or last depending on how you look at it, instead of letting a jack-o-lantern go to waste at the end of the year, try composting it. A home composting system is easy to set up (you can check out my home composting system in my “After the Market” blog) and allows you to cycle the nutrients from your leftover vegetable waste back into your garden. Simply take finished compost from your pile and put it in the garden where your pumpkin was growing. Adding a nitrogen-fixing cover crop like clover, vetch, or field peas to your pumpkin patch can also help put nitrogen back in your garden by converting nitrogen from the air into nitrogen in the soil that plants can easily access. These nitrogen-fixing cover crops do this trough a symbiotic bacteria present on their roots. Amazing, right?! You can get free nitrogen for your plants from the air!
In my garden, I didn’t add extra nitrogen-rich fertilizers to my pumpkins and I didn’t irrigate them. I did give the baby pumpkin plants a little bit of compost, which helped to replace some of the nutrients removed by the previous crop taken from the garden. Otherwise, the air, sun, and rain provided everything else the pumpkins needed. Without excess nitrogen, they didn’t grow rapidly, and they didn’t put on excessive water weight as a result. Admittedly, I wasn’t trying to grow prize-winning huge pumpkins. I wasn’t even trying to grow jack-o-lanterns. Instead, I grew pie pumpkins, which are for eating even though they look pretty enough to be decorative. Pie pumpkins are smaller than jack-o-lanterns, and this year, my pie pumpkins averaged around 4 lbs each, which provides enough pumpkin flesh to make 1-2 pies. I didn’t want huge pumpkins because I didn’t have a lot of room for them in my 1-acre garden and I wanted the flavors and nutrients to be concentrated, not watered down. In my mind, it’s the best of both worlds – a vegetable that is delicious and healthy, albeit small.
If you come visit my stand at the farmers market, you may notice that some of my veggies are on the petite side. That’s because I use my “little pumpkin” philosophy all throughout the garden. My celery is small. So are my eggplants, beets, cabbages, and a bunch of other vegetables. Sometimes it’s because I grow small varieties and plant things close together so I can fit a lot of vegetables in a small space, but oftentimes it’s because I don’t use fertilizer and extra water on the plants. I believe the result is nutrient-dense and flavorful (and not watery) food. Sometimes bigger isn’t always better…sometimes good things come in small packages.