Do Organic Fertilizers Work in the Winter?

Do Organic Fertilizers Work in the Winter?

An article by Travis Key from Lazy Dog Farm

Our last blog discussed the differences in organic fertilizers versus synthetic fertilizers for your backyard garden. We explained how organic fertilizers are made of large, carbon-based molecules that must be broken into smaller forms so the plant can absorb them. We also talked about the benefits of this breakdown process as it relates to feeding your soil biology and establishing a healthy soil ecosystem.

But you may have heard that organic fertilizers don’t work in the cooler months. There is some merit to this statement, but it’s not as black and white as some would make you think. Below we’ll share our experiences using organic fertilizers in the cool-season garden and explain how we’re still able to keep our plants happy in the fall and winter garden seasons.

I will admit that this article obviously has a little regional bias because everyone is not able to grow a garden throughout the fall and winter months. Some of you may live in the northern states and be covered with snow for most of the winter. But believe it or not, most of the country can still grow food throughout the winter. Depending on where you live, you may be limited to cold-hardy stuff like Brussels sprouts, collards, and spinach. Or if you live in the south like us, your fall and winter garden options are extremely diverse.

Enzymes and Their Role

The breakdown of organic nutrient sources into smaller molecules is performed by microorganisms in the soil. This is why quickly transitioning from synthetic to organic fertilizers is tough for many gardeners. If you haven’t established good soil biology, there’s not much there to help you digest these organic compounds so the plants can use them.

Much like our body breaks down the things we eat, microorganisms use enzymes to digest large organic molecules. The rate of enzyme activity is primarily a function of heat. Most enzymes have an optimal temperature for which the enzyme works to break down molecules. Below that optimal temperature, the enzymatic activity will be slowed or completely stopped. And above that optimal temperature, the enzyme can become “denatured” if it gets too hot.
What Happens in Soil?

There’s no doubt that lower temperatures can slow or halt enzymatic activity in soils, but how will this change the effectiveness of organic fertilizers in the cooler months? I think it depends on a lot of factors, but I can tell you that organic fertilizers work just fine for us throughout the winter without any issues. Keep in mind that we rarely get below 25 degrees here in south Georgia, but I haven’t had any issues with nutrient delivery from organic sources in the cooler months.

One of the great things like we like about AgroThrive is the fact that it is “pre-digested” and works much faster than most organic fertilizer formulations on the market. This is why we use it year-round in the spring, summer, fall, and winter garden. It works for us no matter the soil temperature, and we can also count on it to give our plants what they need.

What Factors Come Into Play Here?


I’ve never gardened in any state but Georgia, so I can’t speak for states north of us. I’m sure there’s a threshold for which soil enzymatic activity and organic fertilizer breakdown drastically slows in the winter months, but it’s not an issue here. It seems to me that if it’s still warm enough to grow cabbage, broccoli, cauliflower, and other cool-season veggies, it’s probably warm enough to get organic fertilizers to work.

Reason tells us that the colder it gets, the slower the breakdown of organic fertilizers will likely be. If you’re in the middle of the country or somewhere between the middle and the south, you probably want to plan organic fertilizer applications sooner than later. Consider the slower breakdown in the cooler months and adjust. Maybe consider loading your soil with organic nutrients in the early to mid-fall when soil temperatures are still relatively warm.


Soil moisture levels will also affect the level of microbial activity. A cold and dry winter would not be favorable for organic fertilizer breakdown. Although it might not seem like your garden soil needs a lot of water during the cooler months, be sure to keep it moist. This will keep the microbiology in your soil thriving and allow those organic compounds to be digested.

Soil Health

If you’ve been promoting a healthy soil ecosystem in your backyard garden for years, you’re probably not going to have any issues with organic nutrient delivery in the cooler months. This is why we feel it’s important to feed your soil (and plants) year-round. Even if you’re not actively growing food in your garden during the winter months, consider growing cover crops to keep your soil alive and thriving below the surface.

Thousands of gardeners have been tuning in to The Lazy Dog Farm YouTube channel where Travis covers a variety topics ranging from how to successfully start seedlings to how to make a flavorful hotsauce that packs a punch. Accompanied by his wife Brooklyn and their two boys, the gardens on their 2 acre homestead in southwest Georgia are always filled with a wide variety of vegetables that are enjoyed fresh or preserved for later.

1 comment

  • Bruce Anthony

    In reading this article how temperature, moisture and soil health affect breakdown of organic materials, I was thinking if I added organic granules to my hot compost in the winter. It seems like it would get broken down and made available when I spread the compost in my garden.
    I believe I read Agrothrive can be used directly into hydroponics, is this true thank you

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