News from the Edible Demo Garden
December 2024: Giving the Garden a Rest
Fava beans are an attractive and popular cover crop due to their nitrogen-fixing effects in the soil. Photo: Flickr
After an especially busy summer and fall harvest season, it was time to consider what to plant next in the Edible Demo Garden. In Marin it’s possible to grow vegetables year-round and there are plenty of winter crops such as cabbage, cauliflower, and onions to select. However, another option is to not plant anything during the winter months and give the garden beds some time to rest and rejuvenate. This puts the focus on caring for the soil so that when it comes time for spring planting, the garden will be ready. With this plan in mind, the recent off-season activities for the Edible Demo Garden volunteers have concentrated on methods for giving the garden time to rest. The primary options for resting the garden are planting cover crops and allowing some beds to be fallow for a season.
Planting cover crops
There are many advantages to planting cover crops. Cover crops, sometimes referred to as “green manure”, are an excellent way to protect and improve soil. They increase organic matter, suppress weeds, prevent damage from wind and water erosion, and support beneficial insects and earthworms. Plus, they can look attractive while nurturing the garden.
A field of red clover attracts pollinators and suppresses weeds while giving a garden plot time to rest during the off-season. Photo: Flickr
Cover crops are divided into two main categories: legumes, such as clover and fava beans, and non-legumes, like rye and buckwheat. Legumes have the added benefit of fixing nitrogen by taking it from the air and converting it into a form to be used by plants. Cover crops are turned over when they start to flower and allowed to decompose prior to spring planting.
Two different cover crops were chosen for the Edible Demo Garden. Fava beans were planted in several of the garden beds and in the straw bales used for the summer crops. The latter is an experiment to determine if there is sufficient residual fertility in the straw bales to support another crop. In order to aid in germination and enhance their nitrogen fixing effects, the fava bean seeds were soaked in an inoculant containing rhizobacteria prior to planting. As an alternative cover crop, a green manure mix of bell beans, field peas, and purple/hairy vetch was planted in some of the raised beds. Past experience with crows eating the sprouting seeds necessitated the use of compost, straw, and protective netting to give the cover crop seedlings a fighting chance. The effectiveness of the different cover crops will be tested in spring when it is time to plant again.
Allowing beds to remain fallow
Layers of compost and mulch protect the soil in garden beds allowed to remain fallow.
Taking a garden plot out of the crop rotation for a season can give the soil time to naturally replenish nutrients. It can also be a way to discourage pests, prompting them to move on once their food source is gone. However, fallow garden beds can also invite weeds and leave the soil exposed to the elements. In the Edible Demo Garden, layers of compost and straw were added to suppress weeds and protect the soil in the beds designated to be fallow. The winter rains will keep the soil moist and provide a habitat for earthworms and beneficial microbes.
Click here for more information on cover crops and soil enhancement in the off-season.
