All about plant fertilization

How and when to fertilize Rosemary plant


Rosemary is a perennial and shrub plant typical of the Mediterranean, whose cultivation has spread to practically all the latitudes of the world. Its particular aroma and flavor have made it a must-see species in any kitchen. In ideal conditions it can reach a meter of height with a very dense fallaje. In this article we will be in charge of analyzing everything related to the use of fertilizer for rosemary. When is the right time to apply it, how to do it and what are the best fertilizers. We will also take a moment to list the most important care you must take for your crop.

Fun fact: Today’s etymologists do not agree with the origin of the word rosemary. Some say that it comes from the Latin rose “rose” and maris “sea”, that is to say “rose of the sea”. Others point out that it is from the Latin rhus “scrub” and maris “sea”, therefore, “scrub of the sea”. Similarly, others say it means “sea dew.” Regardless of the exact origin, there is no doubt that it is closely related to the shores of the Mediterranean Sea.

1. NPK values – What do they mean?


If you’ve already fertilized some other garden plant with some commercial fertilizer, you probably notice that each package has three numbers separated by a hyphen. In case you are an inexperienced gardener, you may not know what these numbers mean and how important they are.

Since I consider it extremely important to know what these three issues are, we will begin this post by explaining it. They are what are known as NPK values. Where each of the letters represents one of the main nutrients.

Fertilizer for Rosemary plant
Rosemary plant
  • N stands for nitrogen. It is the main nutrient that influences the growth of a plant.
  • P stands for phosphorous. It is responsible for promoting the formation of roots and the development of flowers and fruits.
  • K stands for potassium. It is very useful to help the transfer of water and nutrients in your plants.

Therefore, each number is the percentage by weight of each nutrient with respect to the total weight. In case you do not finish understanding, we will see an example:

“Suppose you bought a small bag of 5-10-15 mix fertilizer that weighs 1kg. So 50g of the total is nitrogen, 100g is phosphorous and 150g is potassium. The rest is completed with minor elements.”

I think that with the previous example it must have been more than clear that they are NPK values. Therefore, we can continue with this article on rosemary.

2. How to grow this plant


Although we will not go too deep, with what we will see we will make sure that at least you do not make big mistakes. Being able to properly grow this small shrub so that it grows healthy and strong.

Please note that the following list has not been ordered in any way. It has a totally random order, so each point is as important as the previous and the next.

  • Temperature: It adapts quite well to hot and cold climates. Although it really works best in hot or temperate climates. In case the climate where you live has quite strong frosts, it is better that you worship indoors.
  • Soil: prefers soils with good permeability and drainage. Some stony soils are ideal, always avoid clayey soils. Also, the pH range should be kept between 6 and 7.5.
  • Reproduction: the most common way is to sow directly on the ground or in containers. Since the degree of germination is quite low, it is sometimes convenient to buy the plants in a nursery. It can also be reproduced using cuttings.
  • Irrigation: it supports drought periods very well, so it will be important not to overdo it with irrigation. Perform small irrigations on a regular basis, always avoiding flooding.
  • Light: Rosemary loves receiving several hours of direct sun. Therefore, when selecting a location to place it, consider this aspect.
  • Pruning: by pruning you can cut weak and diseased branches, leaving a limited number of main branches. Always keep in mind to properly disinfect your scissors so you don’t transfer infections from one plant to another.
  • Pests and diseases: the most common are those caused by excess water. Therefore, check that it does not exceed the amount of water.
  • Fertilization: rosemary is not a very nutrient-demanding plant. In the same way, we will see in the following sections how and when it is good to apply fertilizer.

3. Best fertilizer for Rosemary plant


Rosemary is a fairly rustic shrub, where fertilization is not entirely essential. Therefore, there is no commercial fertilizer created just for this plant, as there is for many other plants.

Depending on the gardener, you will find those who do not recommend using fertilizers at any time, others who recommend using but only organic, etc. In our case, we prefer not to be so radical, and we encourage a controlled use of fertilizers, which varies according to how and where you grow rosemary.

If you are reading this post, you will probably be interested in learning about fertilizing these other plants.

In general, it is enough to use organic fertilizers like compost or manure instead of the good ones. As long as these are well fermented. But in the case of more intensive crops, it is practical to apply commercial fertilizers. A 12-12-17 mix can be very helpful. If you remember what these numbers represent, you will understand that it is a fairly balanced mix of nutrients.

4. Rosemary fertilizer (How and when)


There is no universal fertilization rule for all rosemary plants, but it will vary depending on the type of soil, type of crop, age of the plant, etc. In the case of large crops, it is always best to carry out a soil study, before designing a fertilization plan. This will allow knowing the nutrient composition of the soil and thus take corrective actions.

As we said that fertilization varies by crop, and to clarify this section, we have divided it into three different types of crops. These include large intensive crops, small home crops, and pot crops. Let’s analyze each of them in what follows.

4.1 Intensive cultivation

Perhaps the most practical plan when fertilizing large rosemary crops is to do it with commercial fertilizers. In this case, many farmers add about 320 kg of 12-12-17 + 2MgO per hectare. The 320 kg should be applied in one year, and the dose can be divided into 2 or 3 applications. The first should be carried out as soon as the harvest is complete.

A fertilization plan more in line with organic agriculture is one that uses organic fertilizer. In case you are one of these types of farmers, you can start by adding 15-20 tons of well-fermented compost per hectare before transplanting. This organic rosemary fertilization can be repeated every year by applying 5 to 10 tons per hectare. Being the right time in autumn and always accompanied by a good soil plow and irrigation. In addition, approximately 200 kg of potassium sulfate (K2SO4) can be added per hectare.

Regardless of whether you opt for more or less organic fertilization, it is always good to do a good soil study. Otherwise, you can add nutrients excessively, something that is not recommended for rosemary.

4.2 Home growing

Most gardeners who grow this herb at home prefer to do it in the most organic way possible. Disregarding any chemicals that can be included in a commercial fertilizer, something that, among other things, can affect taste and aroma.

So what they do is use homemade compost or manure. The latter can be of any farm animal such as cow, goat, sheep, horse, rabbit, etc. It is important that both compost and manure are well fermented. To ensure this, you can check that it is practically odorless and homogeneous brown in color.

Once spring comes, you can spray this organic fertilizer on the base of the rosemary, shake the soil a bit, and then water it abundantly. With the last days of summer, or early fall, you can repeat this application. Then, during the winter, let the plant rest.

4.3 Container cultivation

Although when it comes to containerized rosemary you can repeat the same fertilization process we just saw (section 3.2), it is generally more practical to use a 20-20-20 organic liquid fertilizer. Apply it during spring and summer every two weeks.

When the cold seasons (fall and winter) arrive, you should reduce the dose to rest. The same can be done every two months. If you are going to bring the plant indoors in winter, consider locating it in a place where it receives a few hours of sun.

When you need to change the pot, you can add some compost to the soil. Therefore, you can do without any fertilization during the first season.

5. Fertilizer for Rosemary (video tutorial)


To end this article, and as usual in this blog, we have selected a video. In this case of the Gary Pilarchik channel, you will see how to carry out the transplanting and fertilization of small rosemary plants. There is no doubt that will help you understand more graphically what has been seen so far. 😉

Well, with this we can already finish this publication. I hope there is no question about how you should apply fertilizer to improve your rosemary crop.

If you are reading this post, you will probably be interested in learning about fertilizing these other plants.

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