Friday, October 12, 2018

Fall Cleanup Tips for the Vegetable Garden by Peter Drake

Photo courtesy PlantTalk Colorado

Whether you have made a vegetable garden in a raised bed, an in-ground bed, or a container, now is a very good time to plan for how you can clean up your garden, and put it in order for the winter months to better ensure that, come next year’s planting, your garden will possess good health and balanced nutrition.
Raised vegetable garden diagram, photo courtesy

The best method of ensuring good health is to practice as much preventative medicine as possible and, as with everything else concerning your garden, this is where careful, daily observation and record-keeping are key.  [And, as a side note: If you have not already done so, it is best now to make a diagram of your raised bed, in-ground or container garden—noting where you have planted each type of crop, and writing down as much information as you can remember concerning how that crop performed for you this year: how it has reacted to weather events this season, how it has responded to any watering and fertilization schedule you have followed, and whether it has shown susceptibility to any disease, or insect pest.  When conducted alongside a thorough fall cleanup, this record-keeping will help to plan for next year’s planting and optimal garden health.]

Cleaning up a container vegetable garden for the winter offers perhaps the greatest range of options, depending on your resources and the plants you have grown in the container.  If you intend to follow a warm-season vegetable crop (such as beans, eggplant or zucchini) with a cool-season crop (such as onions, peas or spinach) and that warm-season crop has not suffered from any serious disease which could be transmitted to the next plant via the potting medium, then succession planting is easy: remove the debris of the previous plant, till the potting medium and amend with extra potting medium as necessary to improve texture and drainage prior to planting.  If you do not intend to conduct another planting in your containers this season, then you should place plant remains, and potting medium, on a compost pile, and wash your container with a solution of at least 10% bleach to ensure its sterilization, prior to winter storage—the exception to this is if a container plant is showing any signs of disease.  If it is diseased, then you should bag and dispose of both plant and planting medium separately, and not compost them, to ensure that disease does not spread.

For raised bed and in-ground bed vegetable gardens, practices of cleanup and winter preparation are broadly similar: You should remove all plant debris and, if it is not showing signs of fungal, bacterial or viral disease, you can compost this debris in order to return valuable nutrients to the soil.  If your plans have been showing signs of disease, however, you should bag and dispose of them separately.  This is particularly important for powdery mildew, a fungal disease which is one of the most common for vegetable crops, and thrives in moist conditions where air circulation is poor. Powdery mildew has been more prevalent this season due to the cooler, wetter spring conditions along the Front Range, followed by the present intense heat.  

Plants which have been infected with other diseases, such as fungal Early Blight (most commonly associated with tomatoes) and Tomato Spotted Wilt Virus and Impatiens Necrotic Spot Virus (TSWV and INSV) which can affect lettuce and peppers, as well as tomatoes, should also be bagged and discarded separately, to prevent the disease from overwintering in the garden and affecting next year’s crop.  Furthermore, since these diseases, as well as the pupae or adult stages of some insect pests, can overwinter in certain weeds, or other protected areas such as soil crevices and leaf deposits, it is also best to clean out perennial weeds and gently till the garden area to break up the soil surface.

Annual Ryegrass, photo courtesy University of Wisconsin Extension

Finally, after you’ve removed plant debris, and tilled the soil surface, you’ll want to protect the soil surface of your garden against wind and water erosion, while still promoting microbial life in the soil.  One of the best ways of doing this is to sow cover crop over your garden bed.  A simple crop to sow and maintain is annual ryegrass.  This can be sown as any conventional grass seed (evenly broadcast, raked so that all seeds are in even contact with the soil, mulched with clean straw and watered in sufficiently to germinate) and, while it will be killed by the first winter’s frost, the mat of grass will remain in place to prevent soil erosion, as well as to regulate soil temperature throughout the winter, providing a more agreeable environment for beneficial soil microbes.  Then, come spring, you can till the plant matter into your garden and allow it to decompose approximately one month before you plant the garden, allowing for the greatest amount of available nutrients for your soil.

For additional information, check out the following CSU Extension publications: