The 10 day forecast in East TN shows that night time temps are now consistently above 50F, so it’s now safe to plant your summer crops! I get a lot of questions around this time of year about how much fertilizer is needed. While you might think this has a straightforward answer, I’d like to take a little time to deep dive a bit more into this topic…
Soil pH Considerations
First, nutrient uptake by your plants is highly dependent on your soil pH. If your soil is too acidic or too alkaline, then it doesn’t matter how much fertilizer you apply, your plants may not be able to access it. Here is a great visual showing that most nutrients are available between a pH of 6 and 7.5. If you’re outside of this range, you may be in trouble!
The only way to know for sure what your soil pH is is to get a soil test done. You can buy kits at hardware stores, but these may not be very reliable. Extension offices offer low-cost testing options done by professional labs and I highly recommend you get a soil test done at least every 3 years. If your soil is too acidic (a very common problem in East TN) you will need to add garden lime (calcium carbonate) to your soil, and if it is too alkaline (not common), you’ll need to add sulphur. Out of the 30 or so soil tests our program sent off this year, I’d say at least a third were too acidic and only 1 was too alkaline.
Soil Health Practices
Second, it’s important to keep soil health in mind when we are thinking about feeding our plants. Healthy soils grow healthy plants, but it can take 3-5 years of effort to build up healthy soil if you’re not starting with it. We have a lot of dense red clay in East TN, so it’s an uphill battle in many cases, but one that is well worth it. There are 5 main soil health principles for gardeners, which you can read more about here. They are:
- Keep your soil covered at all times (mulch or cover crops)
- Limit soil disturbances (avoid tilling and convert to a no-till system)
- Increase plant diversity (companion planting and crop rotation)
- Keep living plants & roots in the soil at all times (succession sowing and use cover crops when not growing food crops)
- Integrate animals (harder to do in a garden than on a farm, but consider this to mean adding aged manure to your garden each year)
Now that we’ve got that out of the way, let’s talk fertilizer! First, a “balanced” fertilizer is NOT one that reads 10-10-10. No plant on G-d’s green earth needs an equal amount of nitrogen, phosphorus and potassium. Grow Appalachia’s Mountain Pride (3-4-3) or Seven Spring’s Harmony (5-4-3) would qualify as balanced fertilizers. They provide a combination of quick and slow release nutrients in a form that is safe for the soil microbial life. Conventional fertilizers often burn the soil life and are essentially like feeding your plants steroids.
Because the organic fertilizers contain a lot of slow releasing nutrients, I like to give each plant a ¼ cup of Harmony fertilizer in the planting hole or a ¼ cup per row foot for seeds. This gives them plenty of nutrition for the growing season! I don’t recommend broadcasting the fertilizer over your whole garden and tilling it in. This is a really good way to feed all of your weeds. By placing the fertilizer only in the planting hole or seed trench, you can ensure that it mostly goes towards feeding your crops!
For mid-summer fertilizer applications, I prefer to use a good organic liquid fertilizer. You can scratch the dry fertilizer into the soil around the plants, but this seems like too much work. I recommend getting a spray bottle attachment for a garden hose and soaking the soil around the roots of your plants. One to two tablespoons of fish emulsion per gallon of water applied monthly through the growing season will give a welcome boost to your plants.
So that’s the long answer to a short question! You don’t have to implement everything in the first year, but keep adding what you can to your gardening routine and the benefits will pay off big in future years!