Good afternoon. Does anyone know how one can use fertilizer NPK 12-12-17 (Mg-S) for palm trees or in other words how to reduce the amount of Phosphates or Phosphorus so that the fertilizer does not damage the palm trees growing in soil? In our island I can't find any other fertilizer formula and importing (ordering online) fertilizer is unaffordable.

Other ingredients are:

22% SO3 (water soluble)
2% MgO
0.1% Bor (B, Borax?)

Now if that's not possible and if this fertilizer is useless or too dangerous for palms even in small amounts, what can I use it for/on? Thank you.

There shouldn't be a problem with that analysis. Palms aren't that sensitive to Phosphorus. It's a good all-purpose food that you can use on pretty much everything.

If the palms are growing in the ground, nutrients contained in the soil and available for uptake are key to determining what NPK ratio is appropriate. IOW, no one can offer meaningful advice insofar as how to supplement existing nutritional resources unless acting on the results of a soil test, without which you're essentially operating blind.

If the plants are in the landscape and the soil is sandy, you might be able to assume the lion's share of nutrients will largely be washed away from the roots by rains, which is to say you assume you'll be operating from the perspective that nearly no nutrition is available, a fertilizer with a ratio close to 4:1:6 + Mg would be a logical choice. A fertilizer's ratio and its NPK %s are different. The ratio of the NPK %s are what determines whether or not a fertilizer is appropriate. Example: A high % of containerized plants do best with fertilizers that provide NPK in a 3:1:2 ratio, respectively. There are many popular 3:1:2 ratio fertilizers, including 24-8-16. 12-4-8, and 9-3-6. If all else was equal, all 3 would be equally appropriate. I'm not suggesting a 3:1:2 ratio fertilizer is best or good for palms; rather, that the RATIO is the key.

You'll also want to ensure the fertilizer you're using has all nutrients essential to normal growth; or, that you have a plan to supply all essential nutrients by using additional supplements to cover what the fertilizer you choose lacks.

Too, all plants are sensitive to excessive amounts of phosphorous in the soil or grow medium. While the average plant uses about 6x as much N as P. The 12-12-17 you inquire about supplies roughly 2.5x more P than the plant wants or can use. That can be an issue because an excess of P limits uptake of several nutrients - Ca, K, Cu, Zn, and particularly Fe (iron), so you were justified in your concerns re the level of P the 12-12-17 contains.

What have you observed that causes you to believe the plants are not getting the nutrients they need? Is the fertilizer product you have a soluble product, slow release, or controlled release (like Osmocote)? I ask because it's sometimes better to forego fertilizer applications altogether than to apply a product that isn't appropriate.

Al

Hi @PicoAzores,

You are wise to be concerned about the possibility of applying excessive phosphorus, not just to your trees but also to the soil, where it might runoff and cause pollution.

The 12-12-17 ratio of that fertilizer means it has more phosphorus than the palm tree can probably use compared to the amounts of nitrogen and potassium. It would be better if the middle, phosphorus number, was more like 4.

You can offset this by using less of the fertilizer than would be optimal to get maximum growth (which usually means applying more nitrogen). The fertilizer package may have directions for the amount to use per square meter (or another area size). Calculate the amount this would be, proportionally, for the rooting area around your palm tree. Then reduce it to only 1/3 of that amount to keep the phosphorus low enough. Palms have dense fibrous root systems close to the trunk. Look for information online about fertilizing them.

It appears that your islands have a range of soil types (link below). Some of them will hold phosphorus against runoff. Others won't. Although holding the P from runoff is good for the environment, it can be bad for your tree as the phosphorus can eventually build up to levels that are too high.

See if you can find out what type of soil is in your garden.

https://revistas.rcaap.pt/rca/...

Best wishes! Sometimes I wish I lived where palm trees grow.🌴 Most of the time I'm glad I at least get to visit them once in awhile.
Pat

tapla said: If the palms are growing in the ground, nutrients contained in the soil and available for uptake are key to determining what NPK ratio is appropriate. IOW, no one can offer meaningful advice insofar as how to supplement existing nutritional resources unless acting on the results of a soil test, without which you're essentially operating blind.

If the plants are in the landscape and the soil is sandy, you might be able to assume the lion's share of nutrients will largely be washed away from the roots by rains, which is to say you assume you'll be operating from the perspective that nearly no nutrition is available, a fertilizer with a ratio close to 4:1:6 + Mg would be a logical choice. A fertilizer's ratio and its NPK %s are different. The ratio of the NPK %s are what determines whether or not a fertilizer is appropriate. Example: A high % of containerized plants do best with fertilizers that provide NPK in a 3:1:2 ratio, respectively. There are many popular 3:1:2 ratio fertilizers, including 24-8-16. 12-4-8, and 9-3-6. If all else was equal, all 3 would be equally appropriate. I'm not suggesting a 3:1:2 ratio fertilizer is best or good for palms; rather, that the RATIO is the key.

You'll also want to ensure the fertilizer you're using has all nutrients essential to normal growth; or, that you have a plan to supply all essential nutrients by using additional supplements to cover what the fertilizer you choose lacks.

Too, all plants are sensitive to excessive amounts of phosphorous in the soil or grow medium. While the average plant uses about 6x as much N as P. The 12-12-17 you inquire about supplies roughly 2.5x more P than the plant wants or can use. That can be an issue because an excess of P limits uptake of several nutrients - Ca, K, Cu, Zn, and particularly Fe (iron), so you were justified in your concerns re the level of P the 12-12-17 contains.

What have you observed that causes you to believe the plants are not getting the nutrients they need? Is the fertilizer product you have a soluble product, slow release, or controlled release (like Osmocote)? I ask because it's sometimes better to forego fertilizer applications altogether than to apply a product that isn't appropriate.

Al

The 12-12-17 I got is like blue "granules" must be water soluble I think. Why would they make such fertilizer that may damage any plants? Do you know what it can be used on?

Soil test I don't know how to do it as that's too complicated matter for me.

I wrote all the ingredients in the bag as I provided here all what's described on the bag.

I avoid using fertilizers especially if immediate release and in pots as that killed my palms in the past. But when in this cool climate that lacks heat a palm tree grows 10 times slower than in a hot climate, I would like to speed it up to add some fertilizer around its soil. Yet this is the only formula is available on this remote island and they don't sell anything else nor take any orders for different kind of fertilizers.

Hortaholic said: Hi @PicoAzores,

You are wise to be concerned about the possibility of applying excessive phosphorus, not just to your trees but also to the soil, where it might runoff and cause pollution.

The 12-12-17 ratio of that fertilizer means it has more phosphorus than the palm tree can probably use compared to the amounts of nitrogen and potassium. It would be better if the middle, phosphorus number, was more like 4.

You can offset this by using less of the fertilizer than would be optimal to get maximum growth (which usually means applying more nitrogen). The fertilizer package may have directions for the amount to use per square meter (or another area size). Calculate the amount this would be, proportionally, for the rooting area around your palm tree. Then reduce it to only 1/3 of that amount to keep the phosphorus low enough. Palms have dense fibrous root systems close to the trunk. Look for information online about fertilizing them.

It appears that your islands have a range of soil types (link below). Some of them will hold phosphorus against runoff. Others won't. Although holding the P from runoff is good for the environment, it can be bad for your tree as the phosphorus can eventually build up to levels that are too high.

See if you can find out what type of soil is in your garden.

https://revistas.rcaap.pt/rca/...

Best wishes! Sometimes I wish I lived where palm trees grow.🌴 Most of the time I'm glad I at least get to visit them once in awhile.
Pat

Hi Pat,

I understand I should use less of the fertilizer as if I was just phosphorizing the plant and not much adding N-K for it. So instead of a good handful I will add just a tiny bit around the tree. Yet supply of fertilizers variety and instructions of use is very poor in Portugal and in the Azores islands. You can visit Azores if you have heard about them. It's an easy 4 hour flight from Boston or NYC to the Azores. 9 islands tota and all are different. The climate is like the tropics minus 20F or 10C which means when tropical climate is 20C to 35C (68F to 95F) the Azores is 10C to 25C roughly or 50F to 77F which means it is the same climatic pattern but reduced by 10C. Thus palm trees grow, but only those which can survive without much heat above 27C or 80F. So those palms that need constant 90F or more year round can't be grown in the Azores. I have already made research what tropical palms grow best in the Azores and am growing only those palms. Areca catechu is one of those palms and but it grows so slowly that instead of 15 ft. it is only 5 ft. in height after 10 years of life. Others such as Washingtonia or even Bismarckia are growing quite fast I would say, despite lack of year round heat and even lack of summer heat above 80F. If you can consider an occasional 78F-80F for a couple hours per day a "heat". Otherwise what you get here is 55F to 64F year round with 64F as TOP temperature and 60F as median.

Now regarding our "soil". It's not really a "soil" but rather a large vase... What I mean is that this area was run over by a volcano, lava flows. Thus the "yard" is all solid rock. What I did while I had some funds I bought like 50 trucks of "soil" (dug up from depth elsewhere on the island) and deposited around the field by thickness of about a foot or two feet. Under it is lava stone or solid boulder. Thus not all trees can put their roots deeper than 2-3 feet... and it heats up fast under a sun. Wind topples such trees easily. Can't water too much as supply water is expensive and well or spring is not available here. This is the worst growing conditions ever. Basically means it is equal to growing in vases, cement or stone planters or pots. Trees that like to ave their roots deeper than 2 ft. or let's say 3 ft. are out of luck. Only those trees survive long term that can let their roots into the lava rock or lava slab. Lava slab is probably dozens of meters deep if any soil under it at all. It's a challenge.

I understand I need the formula 3-1-3 or 12-4-12 for my palms. Not in this country. They won't supply me with it even if I paid a million bucks. Thus I must use the only available 12-12-17 or not use it at all.

Pico, I can tell you from personal experience that if you use that fertilizer as per the instructions your Washingtonia will thrive. They are practically a weed here and respond to any fertilizer by growing even faster and lusher. I've used MUCH stronger fertilizers than that on much more delicate plants with no ill effects.

It's not about strength, it's about providing an appropriate balance/ratio of nutrients while still working within the larger framework of the level of total dissolved solids. Since a toxicity (any excess) has the same potential to limit as a deficiency, there is something of an interest on the grower's part to supply a product or products that aren't inherently limiting under existing circumstances.

@PicoAzores has interest in increasing the plant's rate of growth. Nitrogen plays a major role in accomplishing that goal. In landscapes and especially where soils are sandy, nitrogen is commonly the most deficient nutrient. If depending only on the 12-12-17 as a nutrition source, there is no way possible PA can meet the plant's N needs w/o supplying a serious excess of P. If supplying the fertilizer such that the P level is appropriate in the soil, both N and K will be deficient. That doesn't sound like a clarion call or enthusiastic endorsement.

I'm not saying PA can't use the product, even though I wouldn't. I'm saying it's not a good choice. That it doesn't kill the tree if it's used, or it doesn't bring with it conspicuous symptoms, doesn't mean the product is appropriate. If the product had 3 or 4% phosphorous as opposed to 12%, it would be a much better choice. That excess P, with nowhere to go insofar as leaching or percolation, can very quickly result in limited uptake of Ca, K, Cu, Zn, and especially Fe; and, it's the RATIO of nutrients, each to the others, that determines how uptake of antagonists of phosphorous are affected. This means that using it in very small quantities won't change how it affects uptake of the antagonists listed.

Al

The Azores are volcanic islands made out of a lot of aluminum and iron, and very little of anything else. If the only fertilizer available is 12-12-17, maybe there's a reason. Over a few centuries of gardening, maybe the people of the Azores have figured out that's the fertilizer needed in their particular environment?

or, it could be what's cheap to make from locally available ingredients?

Washingtonias do not need heat to thrive (they do great in our climate, which is extremely mild, cooler than yours in the summer) and they are not at all demanding about nutrients (they grow in nearly pure alluvial sand both in nature and in various places around here).

You will likely get good results from that plant by keeping the amount limited. Measure what you use. Start low, observe growth, and go up as needed. If you have a lot of plants, do an experiment with two groups treated differently, which ought to be informative.

I would dissolve the product in water before application in order to avoid toxicity issues and ensure a more even distribution. You will get better results (all things equal) with repeat application at a lower level, if that is possible, because of the soil limitations you have described (nutrients being constantly leached by water). And never underestimate the value of compost, even applied intermittently in the form of mulch (though ideally mixed into the soil) for giving rocky soil long term potential.

I do not know much about boron but it may actually be the most hazardous component of the mix when delivered in excess. There is a relatively small difference between a therapeutic dose and one that limits growth. You can read up on this if it concerns you.

Considering that the fertilizer isn't the only source of nutrients, I doubt that ANY toxicity that might limit growth is an issue. Hundreds of thousands (possibly millions) of people have been using similar products for years without major issues. Plants are much forgiving than you give them credit for.

Considering your location, I would be adding anything organic I could find.

CPPgardener said: Considering that the fertilizer isn't the only source of nutrients, I doubt that ANY toxicity that might limit growth is an issue. Hundreds of thousands (possibly millions) of people have been using similar products for years without major issues. Plants are much forgiving than you give them credit for.

Too much of a good thing is usually harmful, and I guarantee there will be adverse events if the OP adds enough of these granules to the area where the palms are growing. The actual amount required for that to happen is an open question, as I understand this thread. And I don't have any easy answers.

With any kind of manipulation of the environment, I think it's an important first principle to use the least amount of product to get the desired effect. I advocate measurement and restraint. Because once you start sprinkling stuff on the ground (or adding it to the soil in whatever way) you can't really un-sprinkle it a lot of the time. And why use 4 times or 10 times the amount you need if you're paying 4x or 10x the cost for that product.

I say this based on experience, because the fertilizer that I use around the house (blue granules of 24-8-16 with all essential nutrients) for my patio container plants (almost all succulents) is dosed at 1/20 (=5%) of the amount recommended on the package for regular outdoor use in containers. I am glad I tested it at this low dose first, rather than going with the recommended amount. More would have been wasteful.

Hi again @PicoAzores
Thank you for the thoughts about visiting the Azores and Portugal! I wish I could. A friend has spent many vacations in the Algarve and told many stories of its beauty. And great food.

You are very dedicated to having a garden! I've walked on hard lava flows in Oregon in the western USA. I can't imagine having to truck in soil and then garden on top of it! Do you think palms will be in danger of blowing over if they can only root 30 cm or so deep?

@CasaCostero and @CalPolygardener have grown palms and so I think their comments are germane. I especially like Casa's suggestion to start small and watch the response. Also that it is better to add small doses more frequently in your conditions. I do this here for potted plants using soluble fertilizer at 1/4-1/2 strength with every watering. But I can get slow-release fertilizers that work well in soil in our climate. You will create a similar result if you apply small amounts more frequently.

Share some pictures sometime! Your garden and palms, views.

Pat