True or False: It Is Safe To Leave Garden Debris In the Garden?
Keep it? Till it? Compost it? Or does it need to go in the garbage?
Conventional wisdom is about “THE way things are done” around here. Gardening practices have changed over time, sometimes quite radically. It doesn’t mean the changes have all been for the better.
As food production shifted away from family gardens over to larger and larger commercial farms, the way things got done changed. Bigger machines worked the land. Bigger patches of one plant became fields of monocultures. Tilling and bare soil practices became normal as time saving and cost cutting measures.
Those changes were then mirrored back onto family farms and gardens because look these big farms are doing it this way, and they are making money. It must be working.
Except it wasn’t working at all. At least not ecologically.
So now the weather is shifting and it’s time to put the garden to bed until spring and the question is: What do we do with all the spent plants now that winter is coming?
Dealing with fall garden debris
There are several methods of putting a garden to bed and each one has its pros and cons.
Till all the plants into the ground.
Strip all the plants off to a compost pile.
Leave the plants where they are.
And just to be clear, which ever practice is done then the next steps include mulching or cover cropping to protect the soil (because tilling and leaving the soil bare is an intolerable ecological option! )
I covered off most of these practices in last week’s post on putting the garden to bed:
But is it safe to leave debris in the garden?
The conventional approach of stripping the garden down to bare soil either by tilling or moving all the plants off to a compost pile, or some combination of the two steps, is derived from the belief that this is how you minimize pests and diseases.
The idea is that you can break the cycle of pests and diseases by essentially creating a blank slate each year. The problem is that you not only break the pest cycle, you destroy the pest-eaters and all the good organisms contributing to plant and soil health at the same time. So this creates a real conundrum for a grower who doesn’t want to spray toxic chemicals to produce food.
What are your options when it comes to handling plant debris as you shut the garden down?
My rule of thumb is to make decisions based on plant health. Now keep in mind that my gardening focus is on creating high biodiversity and soil health. That biodiversity provides a strong protective force and so in my garden, pests and diseases are already minimized. Still it is important to use proactive measures and here are some guidelines as to what that looks like.
Plants to keep in place - meaning - cut the stems off at the ground level and lay the rest of the plant down and mulch over (or cover crop) include:
All healthy plants
Overmature or rotting veggies from healthy plants
All weeds that haven’t flowered and gone to seed (pulling is usually better than cutting these off)
The tops and vines of root crops that have been pulled can be put back over the soil from which they grew from and covered
Plants to move to the compost:
Oversized stems or plants that are going to interfere with mulching or cover crops
Heavy stemmed plants like sunflower or corn stalks that will take a LONG time to break down and so will recycle faster in a compost
Overmature or rotting veggies if there are too many to leave them in place, or if you are worried about attracting rodents, birds or other scavengers
Pest ladened plants that have been pre-treated (see below)
So what can’t be composted or left in the garden then?
Untreated pest ladened plants
Diseased plants
How to handle pest-laden plants:
The first step is to check for the presence of beneficials that are busy killing those pests. A great example is finding golden (or hardened) aphids on a plant covered in aphids. The presence of these “mummies” indicate beneficial wasps are at work. Likewise ladybug pupae are something to learn to identify and protect.
So if your pest problem already has beneficial avengers hard at work, then I would just lay the plants down right where they are and mulch over them. Remember that next year you are going to practice crop rotation, so you won’t be planting the same family of plants in that spot again. Even if some pests survive, they will have to work harder to find the new patch next spring.
But what if it’s a REALLY bad pest infestation and you just cannot seem to identify any beneficials? Well this is where a pre-treatment trick I developed during my PhD studies come in.
I did my PhD on the invasion of Western cherry fruit fly into my area. These little black and white flies lay eggs in ripening cherries, resulting in worms inside the cherries. This has a significant ‘yuck factor’ when eating cherries, let me tell you!
I was gathering up hundreds of pounds of wormy cherries to facilitate my studies. But what to do with all the leftover, but infested fruits???
My solution was to put the infected fruit into large plastic bags, make sure there was some moisture in the bag (easy with cherries), and tie the bag closed. I left these bags in the sun for 5 to 7 days. The black plastic and sunshine created a cooking effect. In no time at all the cherries inside the bag were brown and denatured. The result was no surviving worms, making the cherries eligible for composting.
This same practice can kill most common garden pests. Put the pest ladened plants into large black plastic bags to cook in the sun. You will easily tell the difference when you later open the bag the the plants and associated bugs are ‘cooked’. Compost the rest of the debris.
Technically you can bypass the bag step if you already have a hot compost where you can put the infested plants directly into the middle of the pile and bury them fully. The wild cards here are whether some pests escape, and whether the pile will get hot enough, fast enough to kill them before they dig out.
Again, the way to avoid all of this extra work, is to create a diversified garden to begin with, and protect your beneficials instead of worrying about pests.
What about diseases?
Diseases are a different problem. Something caused by a deficiency, like blossom end rot in tomatoes, is a localized mineral deficiency problem. Plants like that can be left in the garden.
But other diseases can be more persistent and troublesome. You generally don’t even want these plants in your compost, and you really don’t want to till them into the soil either.
The best strategy for diseases is to remove the entire plant at the first sign of the disease, bag it and throw it in the garbage. Then look for disease-resistant varieties for your garden next year.
Alternatively, if you are struggling with a disease common in your area, then it’s time to become a top garden sleuth. Look for the very best plant that either didn’t get the diseases, or produced food regardless of the disease, and save seed from that plant or plants. Use only those seeds the following year and repeat the process of extreme selection down to only the very best plants. This has been how disease resistant varieties have been created, and the process works quickly if you select the plants diligently.
The Safety of Garden Debris
To summarize the practices here, you can safely leave most healthy plants and over-ripe produce right where it is. You can remove and compost any materials that are too big or interfering with your ability to use mulch and cover crops to protect the garden soil over winter.
Pest laden plants can be left right where they are if you have a diversified garden that supports beneficials, and you practice crop rotation. But you can also pre-treat these plants using the black plastic cooking method and then add the materials to your compost pile.
Diseased plants are the exception. They should not tilled into the soil or composted because some diseases will persist in the soil for many years and they are impervious to tilling and compost practices. The best thing to do here is remove the whole plant at the first sign of disease and throw it away (sad but true). And then work with resistant varieties or stop growing that type of plant altogether.
Convention wisdom of laying the garden bare before winter is NOT an appropriate course of action (EVER) if you are concerned about ecological sustainability and reducing climate change. Garden debris is part of the natural cycling of nutrients between plants and the soil, and it can help you build deeper and richer soil faster than what happens in nature if you handle it well.
Happy gardening!
Not that I have much of a garden but I alwasy leave them as they are. Normally the garden is covered with leaves from the trees nu the end of November. But based on what you said, I should remove the broccoli stems - we grew this for the first time.