Today I want to teach you how to choose the best vegetable fertilizer for your plants and what the numbers on fertilizer mean.
Have you ever stood and looked at the plant fertilizer shelf and had no idea what one to choose? I have. It can feel very overwhelming. Here are some tips I have learned about how to choose the best fertilizer for each one of your vegetables, herbs and flowers.
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What do the Numbers on Fertilizer Mean?
Most plant fertilizer is labelled with three numbers on the container. (As is this fertilizer from Amazon.)
Before knowing what fertilizer to select for our vegetables we need to understand what each of the numbers on the fertilizer means. 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 understand how each nutrient effects our plant. 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 concentrated plant growth.
For example; for lettuce, spinach, cabbage and anything leafy you may want a 20-5-5 plant fertilizer (maximizing leaf production). For carrots, potatoes and beets a 5-20-5 plant fertilizer (maximizing rood growth). And for tomatoes, peppers, squash and cucumbers, your "fruit" bearing plants, a 5-5-20 plant fertilizer (maximizing flower and fruit production).
The above examples may 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 gives 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 and encourages more fruit production. For these I use a 18-18-21. Other vegetables tend grow well and produce without needing that boost as long as you have healthy garden soil mixed with a quality compost. The best fertilizer for annual flowers is 20-20-20, helping them grow to their full potential and producing many flowers during our short growing season. These fertilizers need to be mixed with water prior to applying. Follow the package directions for diluting.