Home Garden Basics The Very Best Organic Fertilizer

The Very Best Organic Fertilizer

by Dawn

Otherwise known as Magic Fertilizer!

Yes, that’s right, magic.  Ok, well, maybe not magic, but you might think it is once you see what it does for your houseplants.  This organic fertilizer legitimately ROCKS (and they aren’t even paying me to say this!)

I discovered Neptune’s Harvest a few years ago when I was looking for an organic fertilizer for my houseplants during the winter.  I put my plants, with a few exceptions, outside for the summer, but being in cold and snowy CT, they all return to the warmth and safety of home by early October. 

If you’re anything like me, by spring, some of your plants are looking a bit ill.  That’s what was happening to me so I went searching at my local garden store, Mackey’s, for a solution, and this is what they suggested.

Let me tell you, these people are geniuses! My plants perked up after just a few applications and started looking happy and healthy.  My grapefruit tree, Spike (read my grapefruit tree story here), started sprouting new leaves within a week, I kid you not!, and looked better than he had in years.  

Neptune's Harvest Organic Fertilizer
BEST fertilizer EVEERRRRRR!!!!!

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Understanding Fertilizer

So, what are the specifics and why is there more than one formulation?  I’m gonna try to explain the three number thing on the front of the bottles without making your eyes glaze over.  Feel free to skip the next few paragraphs if you already know all about the magic of N-P-K.

Nitrogen: The N on the label

N (the first number in series) stands for nitrogen.  Nitrogen is the element in the soil that causes plants to grow nice and green.  If there is too much, your plants may grow beautiful big green leaves without producing fruit or flowers. 

Nitrogen comes primarily from manure and grass clippings, leaves, and that type of thing, although legumes (peas, beans, clover, among others) “fix” nitrogen in the soil. This means that they, with the aid of certain soil bacteria, take nitrogen in a form that is unusable by other plants and make it into a form that can be used. 

That’s why you might see recommendations to plant “heavy feeders”, such as tomatoes, in the same spot you had peas or beans the previous season (more on that in a future blog post, I promise!).

Phosphorus: The P on the label

P (the middle number in the series) stands for phosphorus.  Phosphorus basically helps plants pick up and use the other nutrients it needs.  Without sufficient phosphorus, plants will have small leaves and fail to flower.  Their root systems might also be small or weak.  If the deficiency is severe enough, the plant’s leaves will look purplish. 

If you have had a soil test in your garden and you know you are deficient in phosphorus, bone meal is a good organic option.

It’s possible for plants to be deficient when soil isn’t, because the soil likes to hold the phosphorus tightly and not release it to the plants.  So, if your soil test is coming up okay for phosphorus but your plants seem to be deficient, try applying compost.  It should help plants use the phosphorus already in the soil, making additional supplementation unnecessary.

Potassium: The K on the label

The last number in the series is K or potassium.  Potassium is necessary for the plant to perform photosynthesis, the plant’s energy collection process.  Without adequate potassium, it will not grow adequately and the quality of fruits and vegetables will be lower.  Basically, the plant will die without potassium because it won’t be able to eat.

Fertilizer Comes in Different Formulations

Rose & Flowering Formula

If you look at the bottles, you’ll see that the Rose & Flowering formula has the highest concentration of all three nutrients, but phosphorus is highest.  This makes sense as phosphorus is most necessary to create beautiful flowers. 

Seaweed Formula

You’ll see that the Seaweed formula (You can get it here) does not contain anything but potassium, and I tend to use this as a supplement to the other formulas, not as a standalone.  

Fish Formula

My go-to for my indoor plants is the Fish fertilizer (you can get it here)  It’s not so concentrated that I worry about it building up too quickly in the soil in the pot, and it’s a nice balance of the three nutrients.  It’s also great for seed starting for the same reasons. 

HOWEVER, the fish fertilizer is DIS.GUST.ING!  Seriously.  Brown and smelly and chunky and generally ewwwww!!!!  It’s quite literally ground up fish so I guess that makes sense, but yuck!  In fact, you could make your own by going to a fish market and asking for all their castoffs and guts, but I’d rather buy the stuff, thanks.

Thankfully, you only use a tiny bit at a time in fairly large amounts of water (directions on the back of the bottle) so you won’t smell it once you apply it.  However, you will find, if you have cats, that your plants are going to become VERY popular for awhile after you water with the fertilizer. 

I wish I had taken a picture of my kittens trying to drink the water out of the plants, but I was too busy keeping them away!  The bottle does say not to ingest, although I can’t imagine anyone (except apparently cats) actually doing so!  

How Often to Fertilize

The bottle of Fish formula says to fertilize once a week.  I have to be honest, I have never been that consistent.  If you remember, I mentioned in a previous post that I’m lazy.  Yes, that applies to the houseplants too! 

If you are a good plant parent and you do fertilize that often, I would suggest taking your plants outside on a nice sunny day about every 2 months and flushing them with clear water.  What I mean is that you should run clear water into the pots until it runs out the bottom for a couple of minutes.

This is because fertilizer salts can build up in the potting soil and cause problems for your plants.  The salt comes from the nitrogen and it can keep your plants from absorbing water adequately if the concentration is too high. 

If you want a REALLY technical discussion of salt concentrations in crop plants, check out this article.  

I hope this has been helpful and that you’ll give the magic fertilizer a shot. 

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Posts Related to Organic Fertilizer

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As always, keep smiling and have a crazy organic day!  

best organic fertilizer for your plants
Neptune's Harvest Organic Fertilizer
healthy flowers due to good fertilizer

The Best Organic Fertilizer for Houseplants


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seminte de rosii 08/27/2019 - 9:30 am

Thanks for interesting information. I just want to let you know my easyest own fertilizer I use

1 Tablespoon Epsom salt disolved in 1 gallon water I use it to water tomatoes once in a month

Epsom salt is made up of magnesium and sulfate – both vital plant nutrients.

Dawn 08/28/2019 - 5:02 pm

Great information! Thank you!


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