Is Seaweed Fertilizer Good For Roses | The Definitive Guide

Do you know that seaweed fertilizer contains a range of excellent nutrients?

These include magnesium, nitrogen, potassium, and more.

So, is seaweed fertilizer good for roses? Let’s find out.

(It is).

But before moving ahead, let me quickly introduce the topic to you.

What is seaweed fertilizer?

Seaweed is a type of algae that grows in the ocean.

In other words, seaweed (macroalgae) refers to thousands of species of marine plants and protists that grow in the sea.

Now the question is, what does this mean?

Simply put, the seaweed fertilizer is derived from marine algae. This means that it is made from organic material found in seaweed species.

is seaweed fertilizer good for roses

The best part?

The natural seaweed fertilizer is an excellent source of micronutrients, minerals, and other organic matter for roses.

Before moving ahead, you should know that seaweed fertilizer can be in two forms:

  1. Liquid
  1. Granular

Note: It is mainly used in liquid form, making it easy to mix into garden soil or mulch.

This takes us straight to the next topic.

Is Seaweed Fertilizer Good For Roses?

Yes! This organic option is great for roses.

Overview: The seaweed fertilizer is great for roses. It provides a perfect balance of nutrients as it is a source of nitrogen, potassium, and magnesium. Plus, it is great for soil structure as it results in better water and air movement through the soil. Note that seaweed contains natural plant growth hormones as well.

Let me explain this in detail.

It is a source of nitrogen.

The seaweed fertilizer provides a perfect balance of nutrients for roses.

If I talk about nitrogen, it is essential for roses as it promotes healthy, vigorous leaf growth.

Over here, note that a rose’s ability to produce flowers resides in its leaves.

This means that healthy foliage leads to more flowers.

Interesting, isn’t it?

In the same way, the seaweed fertilizer provides other beneficial nutrients as well. Here are some of them:

  • Phosphorus: It promotes abundant flower production and healthy root development.

Plus, it allows roses to send nutrients throughout their plant system, photosynthesize, and transfer energy.

  • Magnesium: It is necessary to make chlorophyll (pigment involved in photosynthesis).

Moreover, it also allows roses to absorb phosphorus.

  • Potassium: It ensures the production of high-quality flowers.

You should also know that potassium boosts a rose’s immune system, providing it additional protection against insect damage and diseases.


Important Note: If your soil already has a high nitrogen content, seaweed fertilizer can burn the roots (if applied in excess).

Therefore, do not apply too much fertilizer in this case.

The idea is that you should dilute the fertilizer in some cases. I will explain this to you later in this article.

But for now, remember that nitrogen deficiency leads to reduced tiller development and slow growth.

This makes the seaweed fertilizer suitable for roses.

With this, let’s jump straight to the next point.

It acidifies and adds iron to the soil.

This makes seaweed fertilizer great for iron-hungry plants like camellias, gardenias, azaleas and rhododendrons.

But, what about roses?

Remember that roses require a slightly acidic pH (around 6.5). So if your soil is alkaline, the seaweed fertilizer can lower the pH.

Note: If you want to test your soil pH, you can use an inexpensive soil kit from amazon. This can be crucial as it will help you confidently plant your roses in ideal conditions.

is seaweed fertilizer good for roses

With that being said, let’s talk about iron.

Roses need iron as it aids in chlorophyll formation. To be precise, iron promotes nice dark green foliage.

This is why “iron deficiency” can lead to chlorosis (yellowing of leaves).

Simple, right?

This takes us straight to the next point.

Seaweed contains natural plant growth hormones.

These include auxin, cytokinins and gibberellins.

These hormones are essential biostimulants that boost the health of roses. Here are some details:

  • Auxin: It has a positive effect on roots.
  • Cytokinins: It helps with new growth including roots, fruits and flowers.
  • Gibberellins: It supports stem and flower development.

So, here’s the takeaway.

The plants that are grown in soil with added seaweed extract exhibit better fruit yield, resistance to pathogens, increased plant growth, and better germination.

Now, let’s move on to the next point.

It is great for soil structure.

This organic fertilizer is great for your soil health.

Well, why is that?

Seaweed improves the moisture-holding capacity of the soil and promotes the growth of beneficial soil microorganisms.

Here are some of the benefits of microbes in soil:

  • Fix nitrogen for plant uptake
  • Improve soil structure
  • Recycle and regulate carbon, phosphorous and nitrogen

To be precise, the seaweed fertilizer is a good soil conditioner.

is seaweed fertilizer good for roses

The micronutrients adjust the pH of the soil and improve the soil structure and drainage. This makes it suitable for roses.

Now, let’s talk about sustainability.

It is sustainable.

Here’s a thing.

The sustainability of the seaweed fertilizer makes it extremely popular for roses.

To understand this, remember that most seaweed-based fertilizers are made from kelp, a variety of seaweed.

So, the kelp fertilizer positively impacts the CO2 cycle as kelp absorbs a massive amount of carbon dioxide.

To sum it up, the seaweed fertilizer is organic. Plus, it also comes from a sustainable source and can be gathered without damaging the environment.

Simple, isn’t it?

Vegan Gardening:

The seaweed fertilizer is a popular choice for gardeners who avoid animal-derived or chemical fertilizers.

As you already know, chemical fertilizers have a lot of disadvantages as well.

This is when the concept of vegan gardening comes in place – To protect the environment while producing crops.

Related: Is Fish Emulsion Fertilizer Good For Roses | In-depth Guide

Bone Meal Fertilizer For Peonies | Good or Not?

When you know this, let’s move on straight to the next topic.

How to make liquid seaweed fertilizer?

Now when you have decided to use seaweed fertilizer for roses, it is time to make it.

Here is the step-by-step guide.

Collect seaweed:

First of all, you have to harvest seaweed from the beach.

You will simply need a bag or a bucket to collect seaweed that’s washed up on shore. You can also order dried seaweed online.

When you are done collecting seaweed, move on to the next step.

Rinse it:

After bringing seaweed home, rinse it using tap water.

Now, let it dry in the sun. You can now mix it with organic matter (like dry leaves) in a compost bin before applying it to your roses.

Or, you can simply add the seaweed to a bucket. Now, fill it with tap water.

Let the seaweed soak for a month as it breaks down. After this, strain the seaweed tea to remove any leftover seaweed bits that didn’t break.

how to make liquid seaweed fertilizer?

You can use this seaweed tea to fertilize your roses.

Pretty simple, isn’t it?

With kelp meal:

You can also prepare seaweed fertilizer using a kelp meal.

For that, simply mix the kelp meal with water. For proper dilution, I recommend you use 1/4 cup of kelp meal per gallon of water.

Now, stir the mixture and let it sit for a couple of days.

Finally, you have the liquid kelp fertilizer for roses.

This takes us straight to the next topic.

How and When To Apply?

Now the question is, how and when to apply the seaweed fertilizer to roses?

Here’s everything you need to know.


If you have prepared the seaweed fertilizer using the above method, it is time to apply it.

  • Use a 1/4 to 1/2 cup of seaweed extract in 2 gallons of water.

If you are foliar feeding, add two tablespoons of seaweed extract to a gallon of water.

Remember that foliar applications are efficient and effective. So, spray the fertilizer directly on your roses.

The best part?

Your roses will immediately absorb the fertilizer.

In general, apply the liquid to the leaves until it starts to drip off. Here is a general guide to seaweed fertilizer application:

  • For small houseplants or herbs: Mix it in a hand-held spray bottle. Now, mist the plants.

You can also use a watering can to mix it. Then, sprinkle the diluted solution over your plants.

  • For a larger planting area to cover, mix a larger amount of solution. Finally, add it to a sprayer to apply.

Alternatively, simply compost it. Then add it to your garden.

seaweed fertilizer for roses

This takes us straight to the next topic.


  • Like other fertilizers, apply it during the active growing season.

The seaweed fertilizer improves seed germination and early root growth for roses.

Before moving ahead, I have a question for you. Is fertilization in spring a good idea?


In spring, new growth starts. This means that nutrient uptake begins as the soil temperature increases.

So, your fertilizing schedule should be based on how often the rose is blooming.

Let me explain.

Generally, roses should be fertilized after each bloom cycle. Over here, note that most roses bloom between late spring and early fall.

Further reading:

Is Mushroom Compost Good For Tomatoes?

DAP Fertilizer | All You Need To Know

Now that you know this, let’s move straight to the next topic.

The Disadvantages:

The seaweed fertilizer is great for roses.

But, nothing is perfect. Here are some drawbacks of this fertilizer:

  • It has a low NPK value.

NPK refers to the percentage of nitrogen (N), phosphorus (P) and potassium (K) in a fertilizer.

Due to the limited macronutrients in the seaweed fertilizer, you may need to supplement using liquid fish fertilizer.

This takes us straight to the next idea.

  • The shelf life is shorter.

Shelf life refers to the length of time for which the fertilizer remains usable.

Due to the nature of seaweed fertilizer, its shelf life is much shorter than granular inorganic products.

If you want to get the most out of your fertilizer, store it in a tightly closed container at room temperature.

These conditions will keep it stable for a year.

Wrapping Up:

So, there you have it.

Is seaweed fertilizer good for roses? Yes! This organic option is great for roses.

To summarise, it is a source of nitrogen, magnesium, potassium, and other trace minerals. In liquid form, it is fast-acting as well.

However, there are some drawbacks as well.

Overall, I recommend you try this organic option. If you have any questions, feel free to get in touch. Stay tuned for more.

Is Seaweed Fertilizer Good For Roses | The Definitive Guide

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