Q: Should I use fertilizer spikes or the granular stuff found in bags?
A: Broadcast fertilizers work best on trees and shrubs as they feed the whole root area. The disadvantage of fertilizer spikes is they only get to the roots immediately surrounding the spike. If you currently have fertilizer spikes, simply crumble them and spread them under the canopy of the tree or shrub. Gently remove any mulch prior to spreading, especially if you are have cypress mulch, which has a tendency to become compacted. Spread the fertilizer from just outside the trunk of the tree, shrub or palm throughout the whole area underneath the canopy. Water in the fertilizer then replace the mulch.
Adult trees and shrubs, which have been in the landscape for three years or more, need not be fertilized especially if they are growing near lawngrass areas. Remember that fertilizer is not food; the leaves of the plant supply the food for the plant. If the tree or shrub is growing well and appears to be healthy it is probably not necessary to apply fertilizer. Of course, there are exceptions to every rule and palms, citrus and flowering plants fit into that category.
Palms are heavy users of potassium, magnesium, and manganese, therefore give them fertilizers specially formulated for palms three to six times a year. Look for a palm fertilizer with a nutrient ratio as close to 2:1:3:1 (Nitrogen:Phosphorus:K-Potassium:Mg-Magnesium, respectively) as possible. Try to find a fertilizer where the N, K, and Mg are in a controlled or slow-release form. The nutrients will probably be sulfur-coated or resin-coated in order to make them slow release. So look for a formula along the lines of 8:4:12:4, where the last “4″ is magnesium. This will give you a great fertilizer that will keep your palms growing but with less chance of potassium or magnesium deficiencies developing.
Citrus requires fertilization in small increments several times a year but avoid fertilizing from October through February. Acid loving plants such as azalea can be fertilized spring, summer and fall. Camellias can be fertilized before spring growth, after first flush, midsummer and early winter. Always, always, always (did I stress that enough?) follow the directions on the fertilizer label. Look for slow release nitrogen on all your fertilizer purchases.