Figuring Out Fertilizer
Updated: Sep 29
Have you ever stood and looked at the plant fertilizer shelf and had no idea what one to choose? Let me help you.
Types of Fertilizer
Most plant fertilizer is labelled with three numbers on the container. Before knowing what one to choose we need to understand what each of those numbers mean. The first group of numbers is the nitrogen percentage, the next phosphorus and the third group potassium (or potash). Knowing that still doesn't help unless we know what each nutrient focuses on. Think of it this way, nitrogen = leaf production, phosphorus = root growth, potassium = flower/fruit production. Look for a fertilizer with the highest number being where you want to see the most growth.
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For example; for lettuce, spinach, cabbage and anything leafy you may want a 20-5-5. For carrots, potatoes and beets, a 5-20-5. And for tomatoes, peppers, squash and cucumbers (your "fruit" bearing plants) a 5-5-20.
Those would be extremes. We do want to keep the whole plant healthy so choosing a fertilizer with higher numbers in all three categories with a slight leaning to where you want to focus most will give you the best option. The only vegetables that I fertilize with more than compost are my tomatoes, peppers, squash and cucumbers as this gives them a boost with our short growing season. For these I use a 18-18-21. Other vegetables grow well and produce without needing that boost. For your annual flowers 20-20-20 is your best option. These fertilizers need to be mixed with water prior to applying. Follow the package directions for diluting.
How Often should you Fertilize?
This depends on how quickly and how much you want your plant to produce and grow. I suggest fertilizing every other week but even once a month will encourage your plant growth and production.
Don't ever fertilize very dry plants. This will cause burning of the roots because of the high nitrogen levels in the fertilizer. If they were watered the day previously and aren't drooping you should be good to go.
There are also options of using other plants and weeds to make an organic fertilizer type "tea" by putting them in a bucket with water and allowing them to sit and "steep" for a few days. By choosing plants with leaves that are high in nitrogen, potassium and phosphorus you are able to return that directly to your plants through the tea water. This is something I am just learning about and plan to try this summer. Follow along on my Instagram to see how it goes.
Lets not forget compost as fertilizer. It is your most basic type of plant food, containing various amounts of beneficial nutrients. A good compost alone will provide enough food for fast growing veggies like carrots, potatoes, beets and onions.
I hope this helps you feel more confident next time you go to pick up a plant fertilizer. Subscribe to my blog or follow me on Facebook or Instagram for many more growing tips.