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Granular Fertilizer for Hostas – The What Why and How

If you’re a gardener, then you know the importance of fertilizer. Not only does it help your plants grow bigger and healthier, but it can also make them more resilient to pests and diseases. But what kind of fertilizer should you be using for hostas?

In this article, we’ll talk about one type that works well, granular fertilizer for hostas—what it is, why you should use it, and how to apply it. We’ll also provide some tips on choosing the right granular fertilizer for your needs. So read on to learn more.

What Is Granular Fertilizer?

Granular fertilizer is a type of plant food that comes in granulated form of small granules resembling coarse salt. It’s usually sold in bags, and it comes as either a single- or multi- nutrient source formula. It will have three numbers printed on the bag which represent their contents: nitrogen (N), phosphorus (P), and potash (k).

What Are the Three Main Types of Granular Fertilizer?

Granular fertilizers come in three different forms:

  • Man-made chemical fertilizers, sometimes called fast release
  • Slow release chemical fertilizers
  • Natural or organic fertilizers

Chemical Fertilizers

These are fast acting fertilizers, producing the quickest visible results. They are the lowest cost fertilizer you can buy and are a good choice for fertilizing your hostas or any garden plants.

The downside of these fertilizers is they need to be applied regularly throughout the growing season as the fertilizer that is not taken up by your plants is quickly washed away with each watering.

The frequency of application can be as often as a light application every two weeks to provide a study supply of nutrients to your hostas. Or, as little as four times a year.

A quick rule of thumb is your first application should be about a week before the pips emerge. Your last application should be just after the hostas finish flowering.

Fertilizers come in many formulations, and granular fertilizers are no exception. Fertilizers intended for the garden will have NKP values that are the same or somewhat close together. The fertilizers with a high amount of nitrogen compared to the phosphorus and potash values are considered being lawn fertilizers and not applicable here.

Common formulations are 10-10-10, 15-15-15, 10-5-10, 12-12-17, 19-19-19, and the list goes on…

Slow Release Fertilizers

This type of fertilizer can come in a granular form and typically lasts from 90 days to 8-9 months. The 3 month formulation is common in retail stores.

We should normally choose the release time to match your growing season or for a shorter period if you want to reapply the fertilizer during your growing period.

These fertilizers are always more expensive than the chemical fertilizers above. The larger size containers can reduce your cost, especially 50-pound sacks, if you have a large garden.

For more information, see our article Slow Release Fertilizer for Hostas with more details about this fertilizer and using it.

Natural Fertilizers

Yes, organic materials can be processed to produce granulated pelletized fertilizers. Below is a video of an organic fertilizer granulator. A couple of examples of this type of fertilizer are MicroLife Multi-Purpose 6-2-4 and Fox Farm All Purpose 6-4-5.  https://www.youtube.com/watch?v=MGu7yE9q7gg

Natural fertilizers are, by their nature, slow release. Fish fertilizers can last for a few weeks while manures and composts can last the entire growing season.

Cost wise the natural fertilizers are more expensive than the slow-release fertilizers above, but if you want an easy way to use natural fertilizer, this could be your answer.

How Do I Apply Granular Fertilizer for the Best Results?

With granular fertilizers, application is the key. If you don’t apply them properly, you won’t get the results you’re looking for. Here are a few tips on how to apply granular fertilizer to your hostas:

  • Spread the granules evenly over the surface of the soil.
  • Or dribble the granules as a side dressing near or around the plants.
  • Water the soil well after applying the fertilizer, very important.

It is difficult to use a handheld broadcast spreader in an established garden. Sometimes this can be done in the spring before the plants start to grow or emerge.

If the granules get trapped in the foliage or stems of the plants, the fertilizer when wet can burn and even kill a tender shoot. So, be sure and brush off any trapped granules after applying the fertilizer.

How Much Fertilizer Should I Use?

Man-made chemical granular fertilizers have little lasting power. How much you should apply per 1,000 square feet will vary depending on the product you are using.

However, a general rule of thumb is to apply no more than 1 pound of nitrogen per 1,000 square feet every 6 to 8 weeks during the growing season.

An application of one-half pound per 1000 square feet is a safe starting point. The lower application rate would also apply if you are adding any other nutrients to the garden, including compost.

To find how much nitrogen a specific fertilizer contains, look at the first number (nitrogen) of the NKP label. 

If the container is labeled 20-10-10, the 20 tells you that 20 percent of the fertilizer is nitrogen and 5 pounds of fertilizer contains 1 pound of nitrogen.

All the fertilizer in the bag is equal to 100 percent and 20 percent of the bag is nitrogen. Then 100/20=5 pounds of bagged fertilizer to equal 1 pound of actual nitrogen. So we would apply 5 pounds of fertilizer per 1000 square feet or 1/2 pound per 100 square feet.

Another example is the label states the NKP for the fertilizer is 10-12-5, the 10 tells you that 10% of the fertilizer is nitrogen. Therefore 10 pounds of fertilizer contains 1 pound of nitrogen.

Slow release granular fertilizers are simple to use but do not appear to conform to the one pound rule above. This is because as the time over which the fertilizer is released to the plants increases, the amount of slow release fertilizer applied increases and with it the amount of nitrogen.

Osmocote 14-14-14 is applied at 14 pounds (which contains 2 pounds of nitrogen) per 1000 square feet. This fertilizer typically lasts 3-4 months.

Osmocote 15-9-12 is applied at 20 pounds (which contains 3 pounds of nitrogen) per 1000 square feet. This fertilizer typically lasts 5-6 months.

Natural granular fertilizers are so varied that following the label directions is a must for new users and if you have questions, contact the manufacturer. The information above will help you with interpreting the label.  

How Often Should I Fertilize My Hostas?

With man-made chemical granular fertilizers, the 6 to 8 week application period is a good starting place.

If you want to provide a more constant supply of fertilizer and feed them every 2 weeks instead of every 6 weeks, the amount of fertilizer in the 2 week feeding period needs to be reduced to prevent overfeeding and poor quality plants. I find that six weeks is a good starting point.

The math is simple. Three applications in the six-week period would add three times the fertilizer as the six week feeding. To correct this, just divide the 1 pound of nitrogen per thousand square feet by three and feed 1/3 of a pound per 1000 square feet every two weeks.

More work for you and some improvement in your plants. My suggestion is do the six weeks and see how your hostas perform. If they look like they are going downhill towards the end of the six weeks, try a feeding every three weeks.

With slow-release, granular fertilizers again just follow the directions on the label and only vary the timing with experience.

To repeat myself with natural granular fertilizers again just follow the directions on the label and only vary the timing with experience.

What About Granular Fertilizer for My Container Hostas

Should you use ordinary granular fertilizer to feed your container hostas? No, I do not recommend it.

Can you feed your container plants with inexpensive granular fertilizer? Yes, you can and it is done successfully.

Why should you avoid using ordinary fertilizer in your containers?

First, it is difficult to add the correct amounts to a group of containers of assorted sizes and overfeeding can and does happen easily.

Second containers require frequent watering, which quickly flushes out the fertilizer, causing a feast or famine situation. Adding more fertilizer does not improve the situation and is like to damage your plants from over fertilization.

Stick with slow-release or liquid fertilizers. You and your plants will be happier.

Closing Thoughts

Most of us grow plants for the beauty they provide and the sense of accomplishment that accompanies success.

Fertilizers are flexible in that if enough is not applied, your plants will most likely still grow and look good but will not reach their maximum potential.  

Over fertilizing, on the other hand, can be deadly and can stunt the plant’s growth, cause them to be weak and spindly or increase their susceptibility to diseases and insect damage.

This article provides a background for using granular fertilizers. But success usually comes easily by choosing the fertilizer that fits your needs, that you feel comfortable using, and simply following the directions on the fertilizer label.