Fertilizing Schedule for Deciduous Fruit Trees
Fertilization is best done in small quantities throughout the year. If we time our fertilizing according to the plant’s cycle, we make the best of our investment. Just keep in mind, if your tree is growing and fruiting well, you don't need to fertilize. If you are fertilizing every season, make sure that the quantity of fertilizer put on the trees is small. We don't want to change the PH of the soil by over fertilizing. So, here are the seasons and what you can do at the time for fertilization:
Winter season (December to February, or when fruit trees do not have leaves on them)
At this time of the year, I suggest fertilizing with an organic, slow release, even number fertilizer, such as 5-5-5, that contains mycorrhizal fungi and bacteria. Add the amount recommended on the package. If your tree grows great but it is not producing, instead of fertilizer add epsom salt (yes! The one from the drug store - I recommend using an unscented one).
Note: If you are structurally training a young tree (developing the main scaffolds or branches), don't use epsom salt at this time of the year, as it encourages unwanted fruiting during the beginning stages.
Start in December with the fertilizer, adding the amount recommended on the package. (If you are using All Purpose E. B. Stone Plant Food use 1 lb. = 3 cups for every 50 sq ft. for plants in the ground.)
In January and February use the epsom salt. If you have a mature citrus tree that is 5 feet tall, use 2 cups per month; for trees 10+ feet tall, use 4 cups per month. For small trees, 1 to 2 feet tall, use ¼ cup of epsom salt per month. Best practice is to dissolve the epsom salt in a 5-gallon bucket of water and add it to the plant. If your mature tree grows great but it is not producing, add epsom salt for the full winter season following the ratios according to its size. This is also a good time to enrich the soil with compost.
Spring season
At this time you can fertilize your tree with any fertilizer. You can do fruit tree fertilizer or any complete fertilizer (meaning not a single element fertilizer) you have in hand. (I like to use E.B. Stone Organic citrus and fruit tree food ratio 7-3-3) Add the amount recommended on the package. Try to fertilize in small doses throughout the 3 months of spring.
Summer season
Most fruit trees are fruitting at this time of the year. When fruit trees are in full fruit production, we do not want to fertilize with manure of any kind, nor fertilizers with lots of nitrogen. Manure changes the flavor of the fruit, and nitrogen makes trees focus on growth. If we are fertilizing the tree when they are in full fruit production, we want to use fertilizers with micronutrients and small numbers, such as 3-1-2. If your tree is happy (growing well), healthy, and flowering or fruiting well, this will be the season you can skip in the fertilizing schedule.
Fall season (Sept, Oct, Nov)
This is one of the most important moments to fertilize your citrus trees. This will prepare trees for the winter ahead and for next year's growth and production. At this time, use two things alternately: an organic fertilizer (I use All Purpose E. B. Stone Plant Food ratio 5-5-5) and epsom salt.
Start in September with epsom salt. If you have a mature tree, 5 feet tall, use 2 cups of salt. For plants 10+ feet tall, you can do 4 cups a month for the season. For small trees use ¼ cup of epsom salt per month. Best practice is to dissolve the epsom salt in a 5-gallon bucket and water the plant with it.
In October add fertilizer following the recommended amount on the package. ( If you are using the All Purpose E. B. Stone Plant Food ratio 5-5-5, apply 1 lb. = 3 cups for every 50 sq ft. for plants in the ground.)
In November add again epsom salt using the suggestions above.