How to feed your plants
Just like people, plants have their own particular requirements and it is not the best policy (understatement of the year!) to assume they all need the same feeding. Some plants need a lot of love whereas others require very little.
Most important rule: there needs to be balance in the garden. If you feed your plants too much fertilizer that is high in nitrogen you might get a lot more foliage but a reduction in the fruit or flowers that the plant will produce. Why? Well, because the plants will be using that nitrogen as energy to grow faster rather than produce more fruit or flowers. Mother Nature has a lot of talents, but let’s say multitasking isn’t one of them 
Plants are always giving us signs of their food requirements or if they have been stressed. They will wilt, or they might change color, their leaves might curl up or simply drop off. If there is something wrong with a plants nutrition it can often be seen quite easily. It is just a matter of reading these signs and knowing what is going on. As all plants are different, to fully understand the requirements of the particular plants or trees that you are growing you need to get information specific to those plants.
If you find signs of stress in your plants you should take samples to the local nurseries of the leaves and any abnormalities that you might notice in the soil. There might be signs of mold in the soil, which could suggest too much water, and the roots of your plants might be rotting. If the leaves of your plants are turning yellow on the other hand they might be suffering from a shortage of water.
The three most important elements in the soil of plants are nitrogen; for the promotion of leaf and stem growth. Phosphorus; for the root growth and Potassium; which helps in the growth of flowers and fruits.
If you find there are any deficiencies in these areas then additional nutrients will need to be added to the soil. How and what? That’s a different story. A pretty complicated story actualy. You may wanne do a search here: gardening for beginners
