Just like people, in order for trees to be healthy, they need good food and water to be their very best.
A lack of nutrients may manifest in your trees with stunted growth, leaves and roots, discoloration in the leaves, and even small or lack of fruit. When a tree is compromised, it will be more susceptible to damage by pests and diseases.
The easiest way to ensure your trees are getting what they need is to apply fertilizer, and the best time to do that would be in Spring. There are many options including organic, fast and slow-release, liquid, powdered, and granules. If you have sandy soils, nutrients may leach out of the soil and your trees may need feeding more often.
Fast-growing leafy trees like Michelia may need more nitrogen, as well as gross feeders like Buxus.
Too much nitrogen for fruit trees may result in more foliage growth and less fruit. These trees may need more potassium-rich fertilizers. Olive trees will produce more foliage and minimal fruit if there is too much nitrogen.
If you notice signs of deficiency in your trees then use a fast release fertilizer for a quick “pick me up”. Then apply a slow-release compound to sustain the tree through the growing period going forward.
Pots need special attention and will absolutely need to have fertilizer supplied, as the tree cannot send roots out to look for what the tree needs.
Whole tree mulch is a great soil conditioner and with leaf matter, a component of the product, the breakdown of the mulch can contribute to the available nitrogen. Good mulching as always has its advantages.