Have you ever gone to a garden center in search of some fertilizer and you come up to this GIANT display of all types of fertilizers with all these numbers and different names and it is totally confusing? Yeah, me too. But, working at a garden center, you learn pretty quick what the story is with all of the labels on fertilizer. You also learn that using the correct fertilizer for the correct plant or application makes a BIG difference in your garden’s productivity! So, today’s post is all about NPK. What is NPK? Read on to find out!
NPK is the three numbers you see on any fertilizer bag. It might look like this: 20-20-20 or 12-0-0 or 10-52-10. You get the idea. And these three numbers stand for Nitrogen, Phosphorus, and Potassium. Say wha? So in our example 10-52-10 … this fertilizer has 10% nitrogen, 52% phosphorus, 10% potassium. Which all sounds fine and dandy, but what does that mean? Well, let’s break it down!
Nitrogen is the first number listed on fertilizer. Nitrogen is important to plants because it provides leafy green growth and promotes strong stem development. Nitrogen is especially helpful in plants like leafy greens, cabbages, celery, or herbs (where you actually eat the leaves and aren’t concerned with getting a fruit set or blooms). So, for your salad greens and herbs, it is beneficial to provide them with a fertilizer high in nitrogen. You would also want to add nitrogen to your soil if you notice leaves that are yellowing or turning pale. Also, if your plants look spindly and don’t have a lot of leafy growth, that would be another reason to bump up the nitrogen. Blood meal is a great organic fertilizer that is 100% nitrogen and is perfect for when you are troubleshooting a nitrogen deficient plant.
Phosphorus is the second number listed on fertilizer. It provides strong roots and promotes blooming and fruit sets. Therefore, phosphorus is important for most vegetable/fruit production. Fertilizers high in phosphorus promote root vegetables to perform better. Phosphorus also promotes budding for all veggie plants. So, for tomatoes, peppers, eggplant, zucchinis, cucumbers, etc. etc. (any veggie that grows off a flower bud) phosphorus is key in the development. Phosphorus would also come in handy if you have a plant that is huge, leafy, nice and green …. but you aren’t seeing ANY buds, blossoms, fruit. It needs a shot of phosphorus to promote those buds to start. Also, on the root veggie side, if you have gorgeous onion or carrot leaves above ground, but pull a carrot to check on how they are doing and it is spindly and small …. phosphorus might just be your golden ticket. Bone meal is an organic high phosphorus source (with the added bonus of a little nitrogen in some cases).
The last piece of our NPK story is potassium. Potassium promotes overall plant vigor and helps your plant protect itself from diseases. Potassium is really key in promoting healthy plants and making sure that your plants last through the season without succumbing to diseases. Potassium should be available to plants from the beginning to make sure they start off healthy. Any plant can benefit from adding some potassium to it’s diet. Kelp meal is a good source of organic potassium. Potash is also a very high source of potassium.
SO NOW WHAT?
I know, you may be thinking to yourself “seriously, I have to buy all these different bags of fertilizer and add them all separately??” and the answer is NO! If you are planting something specific, or having a specific problem with a plant … then yes, giving it an extra boost of one of it’s key nutrients may be in order. And now that you understand NPK, you will be able to much easier target your fertilizing needs to the plants you have growing! (YAY!)
But, for the most part … if you are just starting out your garden for the year, you are going to want to give your plants a little dose of everything. That is the best thing to do! Start off your plant with all of their essential nutrients and watch them grow big and strong and happy! So, in this case, you can buy an organic fertilizer that already has all 3 nutrients in it! Score! These fertilizers will have a little bit of each key nutrient and will help any garden perform better. I’ve been using tomato tone for a few years now with great results.
Over to you: What do you use to fertilize your garden? Let me know in the comments below!
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