As the leaves change color and fall from the trees, most of us are busy closing up our gardens for the season. But don’t put your garden tools away just yet. There’s a common spring gardening chore that is best done in the fall.
I’d like to make a case for fertilizing your garden in the fall rather than the spring.
It’s accepted wisdom in the gardening community to fertilize in the spring when you’re getting started for the season. But in recent years, we’ve discovered that all of this fertilizing can negatively impact the world beyond our gardens. It’s time to look at fertilizing in a different way, hopefully, a better way.
What’s the Problem with Spring Fertilizing?
Before I tell you why I think fertilizing in the spring is a problem, I’d like to tell you about my summer vacation.
I promise it’s relevant.
This year, my family and I decided to rent a lake house in the Finger Lakes for a week. It was beautiful, right on the lake with a private dock. Visions of swimming, snorkeling, and kayaking permeated our dreams in the weeks leading up to our vacation.
Then we arrived to find a lake that looked like this.
Needless to say, all thoughts of swimming went out the window.
We tried a few times, but whenever we got in and out of the lake, we were covered in this fine, stringy green hair that was hard to get off. No one was going to dunk their heads under the water in that mess. Not to mention, your lizard brain is going into overdrive because you’re not able to see what’s in the water around you.
What does this have to do with fertilizing your garden in the spring?
When we warn about the problems of overfertilizing and fertilizer runoff, we use language that makes it hard to picture the problem. I’ve already done it a few paragraphs earlier in this article. We say things like “fertilizer runoff,” and we talk about how it can “negatively impact lakes, streams and other bodies of water.”
While those warnings are all well and good, they don’t mean too much if you can’t visualize the problem.
This is how it goes with humans.
We have a hard time picturing or caring about a problem unless it’s relevant to us or our experience. So, it’s hard to wrap your head around fertilizer runoff until it shows up quite tangibly to ruin your summer vacation.
Speaking of which…
We arrived at the lake after several days of heavy rain prior to a long period without rain. We were greeted by an algae bloom caused by, you guessed it, fertilizer runoff! Algae thrive on nitrogen and phosphorous. As a gardener, I’m sure those nutrients sound familiar. When rain washed those nutrients from surrounding farms and gardens into the lake – bam – instant algae growth.
Far too often, the fertilizers we choose to use in the spring are nutrients that are meant to be readily available to plants. That means they’re surface-applied. They’re made to be absorbed into the soil when we water, sprayed onto the foliage, or scratched into the surface of the soil. These are all susceptible to fertilizer runoff.
By the way, that goes for your organic fertilizers, too.
That algae didn’t care if it was ammonium from a fertilizer plant or organic liquid fish slurry that was running into the lake – to the algae, nitrogen is nitrogen, and it throws that whole ecosystem out of whack for days.
The worst part about all of this (my vacation aside) is that the fertilizer isn’t doing what it’s meant to – providing nutrients to your garden. Instead, it’s feeding algae in a lake.
Okay, Tracey, then what are we supposed to do? Stop fertilizing our gardens?
Of course not. What I’m proposing is nothing extraordinary; it’s not even a new idea. I’m simply suggesting that the best way to feed our gardens is to feed our soil differently, and that starts in the fall rather than the spring.
(By the way, the algae bloom finally cleared up two days before the end of our vacation. We spent hours in the lake making up for lost time.)
Why Feeding Your Garden in the Fall is Different
Picture a beautiful forest.
There are tall, stately trees, mosses and lichens, delicate flowers that grow in dappled sunshine, strange mushrooms and all kinds of plants growing on the forest floor. Now, contrary to popular belief, there aren’t tiny fairies roaming the forest every spring with bags of fertilizer and jugs of liquid plant food.
Instead, every autumn, the leaves fall, plants die off and rot in place. There is a constant cycle of decay happening on the forest floor, which returns nutrients to the soil. There are two main components to this cycle – the organic matter that’s being broken down and the organisms responsible for speeding up the process, delivering nutrients to the roots of plants.
I’ll bet you’re beginning to see where this is going.
Fertilizing your garden in the fall is not only better for your garden but better for the rest of the land and waterways surrounding it.
Fall feeding is slow feeding. It mimics nature, which is far superior to us in this whole business of growing things.
How is Fertilizing in the Fall Different from in the Spring?
Rather than adding a premixed organic or chemical fertilizer to our garden, which is susceptible to runoff, we add organic materials whose nutrients aren’t available right away. They need to break down before the plants can use them. In this way, the nutrients stay where we want them – in our garden.
Just as in the natural world, we can provide our garden with friendly assistants who help break down organic matter. Worms, bacteria, and fungi all come into play, creating a symbiotic world beneath our feet. Certain fungi and bacteria also attach themselves to the roots of our garden plants to pass nutrients to them.
This creates a living soil, which is better at creating and retaining nutrients.
The best way to take advantage of fall fertilizing is to make the switch to no-dig gardening. Put away your tiller, save your back, and let the soil heal as a new microbiome grows. Whether you grow in raised beds or directly in the soil, no-dig gardening is easy to implement. Cheryl can get you started here.
If no-dig isn’t for you, that’s okay too. It does mean, however, that you’ll have to be more diligent in repopulating your soil each fall with microbial helpers.
What Should I Add to My Garden in the Fall?
One thing to keep in mind is that if you switch to fall gardening, it’s a slow process. It can take a couple of seasons to get a good cycle of decomposing organic matter going. You may need to feed supplementally. However, I recommend getting your soil tested in the spring to see whether or not you need to supplement.
Soil Helpers that Aid in Decomposition & Nutrient Uptake
Worms – a measure of soil health is the number of worms in your soil. If you rarely see one of these wriggly little guys, it might be time to move them in yourself.
Red wigglers are the best option. (Don’t add night crawlers; they’re not good for your soil.) Adding red wigglers in the fall allows them to tunnel around all winter long, digesting organic matter and leaving behind worm castings, a bonus natural fertilizer.
Mycorrhizae – this is a fancy name for the microscopic fungi that live in the soil and attach themselves to the roots of plants. These little guys help decomposing organic matter break down faster and process nutrients, making them available to plants. You can read more about the benefits of using mycorrhizae here.
Beneficial Soil Bacteria – much like mycorrhizae, beneficial bacteria occur naturally in living soil. If you’ve been tilling and fertilizing year after year, you might have lower levels of bacteria in your soil. They also play a role in breaking down organic material into rich, dark soil, and collecting nitrogen from the air and storing it in the soil.
A great option is to choose a product that contains both mycorrhizae and bacteria, such as Smart Grower Supercharge.
Organic Material and Amendments
Now, we add organic materials that have nutrients bound up in them and let the microbiome do its work. If you’re a no-dig gardener, you’ll be layering these on top of your mulch. Alternatively, you can lift your mulch and add these before covering it all up again.
For those who aren’t no-dig gardeners, go ahead and dig your chosen amendments into the soil well. You want to make sure they’re covered and incorporated, as it will lead to quicker decomposition.
Leaves and leaf mold – just like that lovely forest, your soil will benefit from a layer of leaves. If you’ve got a mulching attachment on your mower, give them a good chopping before adding them to your garden. Avoid black walnut leaves as they’re allelopathic and can inhibit plant growth.
If you prefer, you can break down your leaves first and create leaf mold.
Wood Ash – adding ashes from a fire pit or wood stove returns potassium and lime to your soil, both necessary for good soil health. Just be sure you’re using clean ashes, in which nothing like plastic or treated wood was burned.
Grass Clippings – grass clippings are a great source of nitrogen, especially when incorporated well and left to break down over the winter.
Kelp Meal – mix in kelp meal to replenish trace minerals, such as calcium and magnesium. So often, we focus on the big three – NPK – and forget that plants use a whole spectrum of minerals and nutrients to thrive. (By the way, I prefer the Down to Earth brand for soil amendments as their products come in compostable boxes.)
Compost – of course, you can’t forget to add compost. Not only will it continue to break down, releasing nutrients, but it improves soil structure and drainage.
Composted Manure – manure is an excellent source of nutrients and minerals and improves soil structure. Be sure you use well-aged or composted manure so you don’t burn the soil or any perennials you winter over. Cow, horse, chicken, even bat guano are all great choices.
Bone Meal – Bone meal is a source of slow-release phosphorus. Phosphorus is essential for strong roots, as well as flowering and fruiting.
Blood Meal – blood meal is another nitrogen-rich slow-release fertilizer.
Top It Off
Now that you’ve fertilized your garden so things can slowly break down in the off-season, it’s a good idea to keep it all covered.
Mulch your garden – You’ll keep the soil warmer for longer (which will aid in decomposition) and lock in moisture, another key ingredient for everything to break down properly. By leaving that mulch in place, it becomes next year’s starting layer of organic matter to break down, continuing the annual cycle of decay.
Rot in Place – Remove the top of your plants and leave the crown and roots to break down so they can return nutrients to the soil. This is important for beans and other legumes. It’s a myth that planting beans in your garden as a companion plant will boost nitrogen. The bacteria that live among the roots soak up the nitrogen and only release it as the plant decomposes in place.
Plant green manure – these winter-hardy crops are sown in the fall, grow during the winter, and then chopped and dropped before spring so the soil can absorb the nitrogen.
Come the following spring, you’ll have soil that’s packed with the nutrients and minerals your plants need for the coming growing season.
When you switch to fall fertilizing, the organic matter continues decomposing, releasing nutrients in the soil throughout the season. Like the forest we mentioned, your garden is now in a natural cycle that will continue to improve year after year.
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