How To Fertilize An Oak Tree and What’s The Right Time To Do So?

Fertilize an Oak Tree

Guy Lambrechts/Etienne Jeanneret/SDI Productions/Richard Clark/gettyimages

Trees like oaks that require little upkeep are invaluable because they provide a relaxed, shady environment and a haven for birds and other species of life. Nourishing a thriving oak tree ever so often can help it produce more acorns, but it isn’t strictly necessary.


In today’s article, we will be covering how to fertilize an oak tree. So, continue reading!


Broadly there are two main types of oak trees: red oaks, which do well in USDA plant hardiness ranges 3–8, and white oaks, which do well in USDA plant hardiness ranges 3–9.


Skip To:


What Is The Best Fertilizer For An Oak Tree?

To foster a healthy oak tree, it is necessary to cater to the tree’s particular nutrient requirements in the initial stages of its development. These trees aren’t even close to being termed, heavy feeders. However, they can have vascular problems if you do not know how to fertilize an oak tree. These problems can be fatal.


Both flowering and acorn formation require sufficient amounts of phosphorus and potassium nutrients. While other nutrients are essential, oak plants rely on nitrogen the most.


They employ it to encourage thick stem and branch expansion, producing abundant new growth at the foliage level. The optimum NPK for them would have high nitrogen content.


Here’s how to fertilize large oak trees in their initial days with the best fertilizers.


Jobe’s Tree and Shrubs Fertilizer Spikes 15-3-3

Fertilizer for trees and shrubs from Jobe’s works wonders, with a 15-3-3 phosphorus/potassium ratio. With the help of just a few nitrogen spikes that are simple, uncomplicated, and mess-free to use, you can quickly provide your growing oak with nourishment during the entire planting period to achieve excellent outcomes.


Down To Earth All-Natural Tree & Shrub Fertilizer Mix 4-2-4

If you are a newbie, using this fertilizer would be a wise choice.

All-natural substances promote leaf development and shield your oaks from harm from the time they are young saplings.


Jacks Classic No.4 All Purpose Fertilizer 20-20-20

With this well-balanced NPK proportion of water-soluble feed, you can assist in the restoration of nutrient-depleted soil. The demands for feeding a plant throughout the year can be met with this versatile product.

How Much Fertilizer Do Live Oaks Need?

If you’re still wondering how to fertilize large oak trees, know that oaks are incredibly adaptable and resilient, so they don’t necessarily need extra fertilizer to thrive in the landscape.


However, if you provide your oaks with supplementary nutrition in the starting years, you should apply sufficient fertilizer to deliver around two lbs of nitrogen every 1,000 sq ft of planting space. The ideal nutrition ratio for fertilizers is 12-6-6; however, 12-4-8 is also effective.


Best time to Fertilize Oak Trees

If you are looking for ways how to fertilize an oak tree, know that you should do it at the right time. To get the best results from fertilizing an oak tree or any other plant, the best time of the year is in the middle of spring since this is a standard rule that applies to all plants.


The soil is often warm and sunny in the spring, and these are the circumstances in which fertilizer is most likely to be successful.


Fertilizer Tips

How to fertilize Live Oak Tree?

While live oaks in their natural habitat likely wouldn’t gain from fertilization, they can make good use of nitrogen, phosphorus, and potassium-rich fertilizer in a landscaped setting.


Start by applying a slow-release fertilizer with a ratio of 30:10:7, which will continue to be effective for two years. Fertilizer will aid in keeping the root hairs in good condition so that they can continue to do their job of sucking moisture and soil nutrients.


How to fertilize large oak trees?

One must know about the oak tree’s growth rate to correctly fertilize it at the right stage. An oak tree that has reached its full maturity and is in good health does not need any additional food.


Adding fertilizer to a large mature oak tree can actually do more harm than good. Also, when organic matter such as dead leaves and twigs breaks down and get absorbed in the soil, it gives the extra nutrition to the tree.

How to fertilize an old oak tree?

Old trees do not need fertilizers. By the time they turn old they have a developed system and a steady growth. It is not advisable to disturb that. It is essential to fertilize only the young, rapidly expanding trees in the early stages to better their growth.


To keep the foliage of mature trees looking vibrant and healthy, fertilizer may be necessary once every 2 – 3 years till they reach maturity.


Tips to Maintain Oak Tree Health

Let us share some tips on how to maintain the health of an oak tree:


Handling the Root System

If at all possible, avoid disturbing the soil just above plant roots. The outermost border of a tree’s leaf is referred to as the drip line. Reduce the amount of leveling, excavating, and tunneling done and the amount of pedestrian traffic and parking areas done.


When management practices are carried out correctly, the root zone continues to allow unimpeded water and air movement. The region that extends six feet out of the trunk is the most susceptible to damage and should never be touched or fully covered.



When pruning a live oak, there are a few more considerations to make in addition to removing any dead branches that must be clipped to protect public health. Removing dead wood from the tree enables proper wound repair, essential for maintaining the tree’s overall health.


It is also essential to inspect the canopy. If the limbs appear too bulky at the ends, you should selectively thin those limbs to lighten the load and prevent limb malfunction. Once you know how to fertilize an oak tree, you are aware that they require fertilizers in their initial days only.


The rate at which oak trees grow will also slow down as they get older. This is an inevitable component of the life of a tree. If the oak is cared for properly, the tree can continue growing and keep its health and foliage intact for decades.



In most cases, oak trees do not need hydration during dry spells, and in fact, more watering may have adverse effects on trees because warm-moist circumstances can favor hazardous infections. Oak tree trunks, in particular, must not experience any moisture problems.


Natural rainfall is sufficient for most years, but if winters are particularly dry, early spring irrigation may be necessary. Another option is to put organic mulch around the tree’s base to prevent water loss via the soil.


Newly planted trees need supplementary watering when they still get their footing in the landscape. These plants must be watered as frequently as once per week during the dry season.



To prevent weeds from competing with oak roots for water and nutrients, mulch is an excellent addition to any garden. When mulch decomposes, it adds more organic material to the soil, promoting water precipitation, oxygenation in the root system, and the availability of nutrients over the long run.



How do you fertilize oak trees is simple to find because, under normal conditions, a mature oak does not need any extra nutrients to remain healthy.


Extraction of toxic detritus, diseases, or poor development in the oak tree varieties may need the use of additional fertilizer. In most cases, fertilizing young trees can help them become established more healthily.


Related: How long do oak trees live | How much time oak trees take to mature |



 Q. Is natural fertilizer favorable for oak trees?

A. Choosing between fertilizers comes down to individual choice. However, you can make a more educated choice if you know how each fertilizer component functions and impacts the trees. While researching how to fertilize live oak trees, you must have found organic ways to do it as well.


Organic matter contributes to a natural increase in soil fertility, allowing plants to nourish for an extended period while promoting healthy aeration and drainage.


However, for targeted problems and specific deficiencies, store-bought fertilizers are better. If nutrients are provided as needed, growth can be stimulated at a faster rate. However, these chemical based fertilizers don’t contribute much to long-term soil fertility or microbial activity.


Q. What variety of fertilizer is best for Red oaks?

A. When an oak tree’s canopy opens up over terrain and towers over you like a skyscraper, it is a sight to behold. It’s crucial to remember that oak trees often require fertilization if you want them to be healthy and vigorous.


If you’re still wondering how to fertilize an old oak tree variety called Red Oaks, you should know that oak trees require fertilization only in the early stages to reach their maximum growth potential.


Selecting a fertilizer for red oak trees is easiest if you stick to the 12-4-8 nitrogen, phosphorous, and potassium ratio. Fertilizer promotes oak tree growth, which in turn increases the yield of acorns.


Q. How to water an oak tree?

A. Now that we have learned how to fertilize live oak trees let’s look at watering them.

Oak trees, whether young or old, require only once in a month watering. Winter rains will provide enough moisture for a living oak tree during the colder seasons. If it is a dry winter, you should irrigate your live oak tree once or twice, but the water must be slowly discharged to avoid moisture stress.

Q. What’s the worst fertilizing mistake you could make?

A. Since you have understood how do you fertilize oak trees, let’s look at the worst mistakes to avoid while fertilizing:

  • Inefficient water management
  • Using fertilizer at the incorrect time
  • Avoiding a soil test
  • Putting down the wrong kind of fertilizer
  • Using an excessive amount of fertilizer to get quick growth
  • Doing without an insecticide
  • Fertilizing a large mature oak and overwhelming it


To Sum Up..

Fertilizing an oak tree is important but it should be done only in the initial years. Mature oaks do not need fertilizers. The best time to fertilize them is Spring. Just read the instructions given on the fertilizer package before proceeding.