The elegant Magnolia is an ancient tree that has existed on Earth longer than the bees, who love its nourishing pollen and ambrosial nectar.
Out of hundreds of species in the Magnoliaceae family, only a handful grow in residential spaces. These can be either evergreen or deciduous and can range in height from a “dwarf” 8ft to a considerable 70ft.
In order to maintain lush foliage and the large, multi-hued, and fragrant flowers they’re known for, the best fertilizer for magnolia trees will be an important part of their care.
- Best Magnolia Tree Fertilizers
- Choosing the Ideal Magnolia Fertilizer
- Best Magnolia Tree Fertilizer Reviews
- How to Feed Magnolia Trees
- When to Fertilize Magnolias
- Verdict: Best Fertilizers for Magnolia Trees
- FAQ’s Fertilizing Magnolia Trees
Best Magnolia Tree Fertilizers
For effective ways to fertilize these antique bloomers, be sure to read all the way to the bottom. But, if you’re simply looking for the best fertilizer for magnolias, below are my picks for the 6 best performers that I’ve personally tested in a variety of climate and soil conditions.
Best Organic Pre-Flowering
1. Down to Earth Organic Flower Fertilizer Mix 4-8-4
Ideal for use right at the start of your Magnolia’s growing season to encourage bud set and longer-lasting flowers.
Best All-Purpose Fertilizer
2. Jacks Classic 20-20-20 All-Purpose Fertilizer
Expedite healthy root establishment for Magnolia trees, especially those planted in nutrient-depleted soil, with this water-soluble feed. Can be used in a broad range of garden fertilizing applications.
Best Fertilizer Granules
3. Shake ‘N Feed Flowering Trees and Shrubs 18-6-12
Once flowering has finished, apply this granular feed to boost resistance to pests and diseases throughout the summer and lush, winter foliage.
Choosing the Ideal Magnolia Fertilizer
To encourage an abundance of large, fragrant blossoms, the specific nutrient needs of Magnolias must be met. These trees are not considered heavy feeders and grow best in fertile, nitrogen-rich soil.
Magnolias rouse from winter dormancy by absorbing phosphorus and potassium from the soil, before nitrogen. This is why for varieties that bloom in spring, I use a high phosphorus fertilizer pre-flowering 4-8-4. Then switch over to a standard tree and shrub fertilizer such as a 16-8-16 after flowering. A standard 10-10-10 top dressing will also be fine if that is what you have to hand.
In order for all this seasonal beauty to grow in a healthy, unforced way, a gradual, consistent approach has proven best for fertilizing magnolias of any variety. On this basis use a slow-release fertilizer in spring or apply a regular top dressing, throughout early spring into early summer.
Pro Tip: While nitrogen is more critical than other macronutrients, the more fertile your soil is, the less it will need. In this case, an equally balanced feed (like a 10-10-10 NPK) would be more appropriate.
Understanding N-P-K Ratio
Choosing the right NPK is easy when you understand what your trees need, as determined by a quality soil test. The results of which will determine a suitable ratio of nutrients to supplement what your soil is already offering. But, what is an NPK, exactly?
An 18-6-12 NPK, for example, has 18% nitrogen, 6% phosphorus, and 12% potassium. Every plant requires these macro-nutrients for optimal health. Different NPK ratios are designed to support varying environmental conditions, like soil quality.
Nitrogen (N) – is a key component in chlorophyll formation, encouraging green color and the creation of plant food via photosynthesis.
Phosphorus (P) – plays a major role in the growth and overall structure of trees. Promoting healthy root development and accelerated tree maturity.
Potassium (K) – drives the circulation of water, nutrients, and carbohydrates throughout plants, shrubs, and trees.
Magnolia Soil pH and Nutrient Uptake
The best soil pH for trees, in general, varies between species. Many of them are quite tolerant of soils that range from alkaline to slightly acidic.
Magnolias, in particular, grow most successfully in an acidic pH between 5.0 and 6.0. Testing the pH around your magnolia may prove advantageous. Especially if your tree is showing signs of deficiency, stress, or a lack of blooms.
When soil pH is below 5.0, nutrients become more mobile. Meaning they become too accessible and are absorbed in excess of what your tree needs. A ph above 6.0 locks soil nutrients in place, making them inaccessible to roots. This issue inevitably leads to nutrient deficiencies and stunted growth.
Granular Vs Liquid Fertilizer
Slow-releasing, granular fertilizers are commonly preferred, over liquid options, as the best fertilizer type for magnolia trees.
Granules break down slowly, with the help of soil microbes, available moisture, and soil temperature. Supplying the kind of steady, consistent access to nutrients that magnolia trees most benefit from. And they can often do so with just one application for the entire growing season, depending on the brand.
Of course, it’s tempting to go for fast results, especially if you live in a region with a short growing season. But, large doses of liquid nutrients are absorbed quickly and usually all at once. This surge can cause irreparable damage to magnolia trees and, unfortunately, makes accidental over-fertilizing quite common.
That aside, liquid fertilizers do have their benefits. When new magnolia trees are planted in less-than-fertile soil, liquids offer an immediate uptake of nutrients for faster root establishment and the appearance of new growth.
Even if you regularly use slow-release fertilizers, a quick boost of specific liquid nutrients may also benefit during big growth spurts, to accommodate for any deficiencies, or in times of drought.
Liquid Concentrate or Spray
Liquid fertilizers come in concentrated, pre-mixed, and water-soluble granule forms. These carry nutrients directly to roots when used as a soil drench or in slow-drip irrigation systems. As a foliar spray, liquids can provide quick relief for chlorosis (yellowing leaves).
Liquid feeds are often more economical and may show faster results. But, they don’t necessarily work better than slow-release options, in the long term.
As mentioned, over-feeding is one of the most common causes of tree failure. This is especially so with liquids and could lead to root and foliage burn. So, caution is recommended with these, as is following exact manufacturer directions.
Granular fertilizers (both organic and synthetic) are easy to use and can provide consistent nourishment for up to nine months. Nutrients are released from each granule as warming temperatures and soil moisture slowly melt their coating away.
The biggest benefit to these is the gradual flow of nourishment to plant roots. Rather than inundating them with a blast of heavy nutrients all at once, when they don’t need it.
Granules are applied by casting them evenly around the base of trees, shrubs, and plants. No watering is needed to activate them and is less likely to leach into nearby surfaces or groundwater.
Spikes are highly convenient to use, especially if you have lots of potted trees. Pre-measured in various sizes, they’re easy to push into loamy soil and run little risk of burning.
The soil around mature magnolias tends to get compacted, making it difficult to insert spikes. A perk of spikes is that they can be broken up and evenly worked around large trees. Providing the same convenient nutrient flow.
Nutrients are released from spikes by increased moisture and soil microbes and carry the added benefit of stimulating an increased resistance to disease and pests. Unused portions can then be stored mess-free.
An Organic vs Synthetic Comparison
Deciding between organic and synthetic fertilizers for your magnolia is simply a matter of personal preference and end-result expectations. However, an understanding of how each works and affects your environment can support an informed decision.
Organics are plant or animal-based and contain nutrient levels that mimic what would naturally be available to trees in the wild. These options also increase soil fertility and nourish trees for longer, while encouraging proper aeration and drainage.
Synthetic fertilizers are mass-produced using minerals and chemical compounds. They can provide a big boost to branch and bud growth by providing higher levels of nutrients than plants would normally have access to. But, have little to no impact on healthy, microbial, soil activity, soil texture, or long-term fertility.
Best Magnolia Tree Fertilizer Reviews
Magnolias grow best in regions with warm summers and mild winters. But, it is possible in colder regions to pot smaller varieties and winter them over indoors.
I have several different magnolias around my garden, so I’ve had the opportunity to test several different fertilizer options. The following are my picks for the top 6 performers, based on NPK results, versatility-of-use, and product features that can accommodate most soil types.
- Effective on all flowering trees and plants
- Formulated for vigorous growth, beautiful blooms, and healthy plant stock
- May attract pets and wildlife with an organic smell
If you’re looking for something completely organic, I’d say you’re in safe hands with Down to Earth Flower Fertilizer. The increased phosphorus in this NPK is just what your Magnolia will need as it comes out of winter dormancy and gears up to bloom.
Given that nutrients get absorbed at a faster rate in pots, I chose to test this product on my collection of potted, dwarf magnolias. Within days, new buds appeared, and leaf shoots began to turn a darker, glossy green. I found that blooms seemed to last just that bit longer, as well.
How To Use: For new saplings, add ½-1 cup per hole, mix into the soil, and water in the well. For mature trees, side-dress ¼-½ cup per plant, once each month during the growing season.
- Optimal nutrition for bud production and green foliage
- Dissolves faster and cakes less than other top brands
- It may give off an earthy odor
These water-soluble granules from Jack’s Classic have become a popular choice for me in helping new, ground-planted magnolias become established, especially in poless-than-desirableor soil.
After planting a few saplings, I tested this as both a soil drench and a foliar spray. Within just a few weeks, healthy root growth had begun. As was evident by more abundant blooms than I expected and vibrant, green, and copper leaves.
The versatility of Jacks Classic knows no bounds when it comes to practical feeding applications in and around the garden. It can be used as a fertilizer for vegetables, trees, shrubs, border plantings, as well as pots. It’s become my ‘go-to’ when something needs fast nutrients at any time throughout the growing season.
How To Use: Apply 1 tablespoon per gallon of water used. Repeat every 10-14 days.
- New foliage and buds appear in just two days
- Formulated to improve soil pH for neutral or acid-loving plants
- May cause root and leaf burn, if not watered in thoroughly
Miracle-Gro is one that I like to include in my tests, to see how it holds up to the competition. I shook this nitrogen-focused feed around my mature magnolia (one that I knew had a soil pH issue).
Within one week, the foliage color changed from brown to green, and new flower buds appeared. By adjusting the pH, my beautiful magnolia was now better able to absorb nutrients.
In addition to using this as a feed for aged Magnolias (that tend to require more nitrogen), it can also be used to keep foliage vibrant and pest-free, once flowering has finished.
How To Use: For ground-planted shrubs, shake the recommended amount onto soil within the drip line. In pots: work up to 2 tbsp into the soil. Water both thoroughly after application.
- Contains patented probiotics for healthy soil
- Certified organic by the OMRI
- May be attractive to pets and wildlife when applied as a tea
People and pet-safe products give me a lot more confidence when letting my kids and dogs run around where I’ve fertilized. This is similar in application method to Miracle-Gro’s Shake and Feed. But, completely organic, with seven different strains of beneficial microbes.
I tested this on two different magnolia trees. I scattered dry granules within the dripline around one. I then diluted the granules into a tea and soil-soaked the other. The earthy smell definitely caught the attention of my canine “helpers”, but I got the same amazing foliage and bud growth from both.
How To Use: Scatter or mix the label-recommended amount directly onto the soil. Water granules in well. Dosage will be specific to container size, plant size, and ground plantings.
- Gentle enough NPK for well-composted soil
- Fast growth in just one season
- NPK ratio may be too low for trees in poor soil
This slow-releasing, granular option from Scott’s performed really well on potted, Babydoll Magnolias that I have growing in well-composted soil. Alleviating my concern about too much nitrogen causing root burn.
The higher ratio of phosphorus and potassium increased the number of blooms on my dogwood and hydrangeas, as well. Win-win!
How To Use: 1 cup spread over every sq ft of the growing area within the drip line feeds for up to 2 months. Work granules into the top 3” of soil and water thoroughly.
- Specially formulated to increase flower and fruit yields
- Higher pH for acid-loving plants
- May require a higher dose if applied to mulched soil.
As an alternative to Dr. Earth granules, this Holly-Tone mix also contains beneficial microbes and a well-balanced NPK. With added sulfur to balance out your soil pH, this 4-3-4 formula really has it all.
If that’s not enough, it’s also formulated to help increase tolerance to colder climates. This certainly gives gardeners a little farther north an edge, given that Magnolias typically grow in warmer climates.
How To Use: For shrubs, 1 cup per foot of branch spread. For trees, 1 lb per inch of trunk diameter. Once in spring, then repeat at half the dosage in fall.
How to Feed Magnolia Trees
Magnolias are not heavy feeders and therefore benefit most from a gradual fertilizing approach. Using a slow-release fertilizer will provide mature trees with an effectively steady flow of nutrients.
Heavier-feeding saplings may initially benefit from a faster-acting liquid that supports rapid growth and root establishment.
Too much, though, may result in forced growth and weak branches that are vulnerable to pests, disease, and frost damage. Magnolia trees, in general, grow healthier in form and color, when allowed to grow at a natural pace.
Fertilizers with a higher percentage of nitrogen, and ample amounts of phosphorus and potassium, will encourage bountiful blooms, vibrant foliage, and a robust tree structure.
Naturally, each brand will have different instructions. However, when using granules, the recommended application rate is 1/10 lb for every inch of tree trunk diameter. Applying these just before a forecasted rainfall will hasten activation.
Liquid fertilizers should be applied using a watering can or a hose attachment, during the cooler hours of the day to prevent scorching.
Avoiding Fertilizer Burn
The most common cause of fertilizer burn is the over-application of it. That’s why it’s important to test your soil to make sure your Magnolia actually needs it. Take trunk measurements, as well, to ensure you’re applying the most beneficial amount.
Remember, too much liquid nitrogen can burn roots when applied to the soil, and leaves when sprayed. Too much potassium and phosphorus can leave excessive salts in the soil that will quickly absorb all available moisture, dehydrating your trees.
Symptoms of over-fertilization include:
- A developing crust on the soil surface
- Yellowing or wilting of branches and leaves
- Out-of-season leaf and bud drop
If caught early, there are steps you can take to try and revive your Magnolia. Remove the dying or wilting branches and leaves. Thoroughly water the area where you previously fertilized, to flush out the excess. Then, cover the root zone with mulch to facilitate moisture absorption.
When to Fertilize Magnolias
Magnolia trees experience a rapid surge of growth in spring, as they wake from winter dormancy, often putting out flowers before the foliage. Once foliage emerges, growth slows down a bit. To get the highest benefit from your fertilizer, you’ll want to apply it before, or just as new buds begin to appear along the stems.
If you feel your magnolia needs a second dose, apply it no later than mid-July. Slow-releasing fertilizers need time to take effect. Fertilizing any later than this will stimulate new growth that can be damaged by an early frost and leave the tree, as a whole, vulnerable.
If it experiences stress from summer drought, fertilizer should not be applied a second time. Roots, weakened by a lack of water, can become burned or shift into survival mode. Sending out new growth and blooms when it lacks the energy to do so.
Another timing factor will be soil condition. For Magnolias planted in sandy soil, splitting the applications has proven effective. Once in early spring and again in late spring.
Fertilizing Magnolia Trees Pre-Blooming
Applying fertilizer in early spring, just prior to the swelling of buds, will focus a proportional amount of your Magnolia tree’s energy on the natural occurrence of producing abundant blossoms before the foliage. The balance will go toward lush greenery.
Watering well, at this time, is equally as important. Water allows nutrients to be better absorbed and circulated throughout the tree. Increased sunlight will also facilitate bud production. Keep this in mind when choosing a planting site.
Before fertilizing, it’s a good idea to test the soil to see what nutrients, if any, were depleted during the previous year. The result will give you the opportunity to adjust what you apply, to accommodate any revealed deficiencies.
But, a lack of blooms may not indicate a problem. Some magnolia varieties don’t bloom until they’re at least three years old, while others wait until they’re 10 years old.
How Often to Apply Magnolia Fertilizer
How often to fertilize your Magnolia trees will be dictated by the brand you choose, soil quality, and your tree’s age and size. Yet, because most fertilizers are made to accommodate several different plant types, make sure that the NPK meets your magnolia’s specific nutrient needs.
Trees growing in fertile soil may not need any at all. Yet, when trees are hungry, the soil may become depleted of nutrients quickly.
In this case, mature trees will need their first dose of slow-release fertilizer, in spring, as buds begin to emerge. Dr. Earth’s organic granules require a follow-up application in 6 weeks. Miracle-Gro’s shake n’ feed option lasts for up to 3 months.
If you have nutrient-deficient soil that needs an immediate boost, Down to Earth’s organic flower mix and Jack’s Classic triple 20 work fast to provide tired trees with what they need to return to radiant health.
Verdict: Best Fertilizers for Magnolia Trees
The verdict is in! The best magnolia fertilizer will primarily depend on soil quality and tree age. Magnolias benefit from a boost of phosphorus and potassium ahead of flowering, making Down to Earth Organic Fertilizer the perfect option right at the start of Spring.
Best Organic Pre-Flowering
1. Down to Earth Organic Flower Fertilizer Mix 4-8-4
Ideal for use right at the start of the Magnolia growing season to encourage bud set and enable flowers to last longer.
For new plantings and where soil fertility is an issue, Jacks Classic All Purpose Fertilizer will help fix nutrient deficiencies and encourage strong and healthy growth from your Magnolias.
Best All-Purpose Fertilizer
2. Jacks Classic No.4 20-20-20 All Purpose Fertilizer
Help get new Magnolia plantings established, especially when planted in nutrient-depleted soil with this water-soluble feed. Can be used for a wide variety of garden fertilizing requirements.
To see Magnolias through the rest of summer, post-flowering, you need Miracle-Gro Shake N’ Feed. Working this into the soil will increase nitrogen and potassium availability to ensure healthy foliage and resistance to pests and diseases.
If a bit more potassium is needed to boost nutrient and moisture circulation, then Espoma’s Holly-Tone granules will increase your chances of blooming success.
Best Fertilizer Granules
3. Shake ‘N Feed Flowering Trees and Shrubs Plant Food 18-6-12
A granular feed that can be used once Magnolia flowering has finished. Works to enhance lush, long-lasting foliage and resistance to pests and diseases throughout the summer months.