I am planning to mix top soil and cow manure with 1:1 ratio and use for growing vegetables, flowers, plants in a plastic container/pot. I will be using fertilizers for the plants with NPK 16-12-12 as per the recommended usage in the pack. Will the plants grow well?
The answer is "maybe." Here are some factors to consider:
- Is the cow manure is well aged (composted) or is it new? It's important that it be aged for it to work with your plants, as explained in this article: Turn manure into compost for your garden
- When properly used, manure eliminates the need to apply chemical fertilizer, since they both supply, the three major nutrients needed by plants: nitrogen, phosphorus and potassium. Here is another article specifically devoted to fertilizers: Fertilizing Your Garden
Finally, you might find the information in this OSU publication helpful: Growing Your Own (EM9027). It covers everything you need to know about vegetable gardening in the PNW. Good luck!