Q.when is the best time to fertlize my plants
I bought some tomatoes and some roses and I heard that you need to feed the plants to grow healthy. I bought my tomatoes and transplanted them in a planter container last month, and the roses that I transplanted three days ago in a planter. How soon do I feed my plants? (The potting soil I bought says it has fertilizer already in it (Miracle Grow, up to 6 months.)
Fertilizing is an important subject, and there are lots of kinds of fertilizers, and the timing depend on the kind of plant, your climate and soil, and the type of fertilizer you're using. Good for you for wanting to learn. This article will tell you a bit about fertilizing tomatoes: https://www.gardeningknowhow.com/edible/vegetables/tomato/tomato-fertilizer.htm
and this article talks about fertilizing roses: https://www.gardeningknowhow.com/ornamental/flowers/roses/rose-fertilizer.htm