Redhatlady, I'm not a fan of synthetic fertilizers.* They leave behind residual salts that can harm plants over time, they don't have all the micro-nutrients of organic fertilizers and are like steroids for your plants.* By that I mean they force a flush of growth that is tender and juicy, just what insect pests perfer.* Synthetics also feed the plant and not the soil.* It's best to have good soil feeding your plants.* I prefer fish emulsion mixed with seaweed or with kelp.* You can also get that at your local Home Depot, Lowe's and nurseries.* It doesn't smell good so don't inhale, but the smell dissipates after watering.
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.