How to Make a Fertilizer Regime for your Roses


Healthy roses need trace elements otherwise known as nutrients, water, and carbon dioxide to grow and flourish. Most of these basic requirements occur naturally in the crops environment. However to obtain maximum gains from roses, continual replenishment of essential nutrients is important.

Roses are hungry crops that need more nutrients than any other plant. If soil or media has an inappropriate composition for roses then they will not thrive (or maybe will not grow at all).


To prevent this being a problem, samples of soil are often analyzed, and nutrients added before planting the seedlings.

Fertilizer Regime

Roses typically responds to a given amount of nutrient in any of the following three phases

1. Deficiency Phase – Inadequate nutrient levels leading to starvation
2. Luxury Phase – Adequate nutrient levels leading to optimal growth
3. Toxicity Phase – Excessive nutrient levels leading to scorching

To achieve optimum rose performance, emphasis should be put on a fertilizer regime based on media analysis report. In commercial rose production, fertilization is normally through a nutrient solution applied through the irrigation system.


What is Nutrient solution?

A nutrient solution is a solution that contains all the nutrient elements in optimum concentrations and proportions. Experiments show that frequent application of water and nutrients is paramount to realize stability in water and nutrient supply. The more stable and uniform the provision and distribution of water and nutrients, the better the effect on the rose plant growth.

Some elements such Nitrogen, Phosphorus and Potassium are taken up by the roses in considerable large quantities and for that reason are rapidly exhausted. For this reason, you should supply all the necessary nutrients regularly to avoid any deficiencies. This requirement is not only based on the total uptake of an element but also the mutual relationship between the nutrient elements and the root environment.

The nutrient solution is supplied to roses in a process that is technically referred to as fertigation. Which in a nutshell means providing dissolved fertilizers through an irrigation system. In this process water quality is just as important as the nutrient elements required.


Water quality in a fertilizer regime

I happen to interact with technical managers responsible for crop nutrition. I see most of them get sub-optimal results in their feeding programs because they disregard the importance of good water quality. Please don’t make this mistake.
When we talk about water quality, three important aspects come to play;

1. Physical water properties
2. Biological water properties
3. Chemical water properties.

Physical water properties; comprises a broad range of factors such as temperature and suspended solids that may be a potential problem. How can they be a problem? Suspended solid for example soil particles can clog the irrigation system and drip lines thus causing damage to irrigation equipment. Clogging can also deny the nutrients a smooth flow to the roses. It is important to ensure that the water is well filtered to avoid this problem.

Biological water properties: Problems associated with this water aspect is that of microbes, algae, and diseases. Algae and bacteria can harm the crop by clogging the irrigation system and attract certain fungi that can infect the roots of the rose plant. To prevent algae from invading the water reservoir, it is recommended to cover it to avoid sunlight and by applying copper sulfate to suppress the algae from developing.

Chemical water properties: This is by far the most important aspect and should be given enough attention. Chemical water properties include parameters like pH, EC, alkalinity, hardness and nutrient composition. Let’s go through first two parameters separately.


pH and its implication on the fertilizer regime

A measure of a solution’s acidity or basicity is what we are referring to as the pH. It ranges between 1 and 14 with 7 indicating the neutral point. It determines, among others, the absorption of nutrients by the plant

The optimum pH level for a rose plant is between 5.5 and 6.5 with small variations depending on the growing media. For example, soil the range is 5.8-6.8 while for hydroponics it varies between 6.2 and 6.4.

The optimum level is that which all the elements are sufficiently available to the plant appropriate proportions. It is imperative to measure the pH more often and make necessary adjustments. You can achieve this by using a well calibrated digital electronic pH sensor.

Electrical conductivity (EC)

EC is a measure that indicates the amount of total dissolved ions in the water. EC should not be constant since it depends on the growing season and the media. Increasing the number of fertilizers increases the EC and vice versa.

Just like the pH, the EC should always be monitored with a well calibrated digital electronic sensor for both the solution and the media. Preferably on a weekly basis on the same day and at the same time.

Note: A higher EC level causes lower uptake of water in roses and hence less growth.


Nutrient elements in a fertilizer regime

The nutrients are grouped as macro elements that are needed by the roses in large quantities and trace elements (microelements) taken up by the plant in small amounts. All these groups are essential for the growth and survival of the roses.

The macro elements include; Nitrogen, Potassium, Phosphorus, Magnesium, Calcium, Sulphur and Silicon. The micro-elements on the other hand, include; Boron, Molybdenum, Iron, Manganese, Copper, and Zinc.

Most of the times these elements are commercially available in the form of compounds. If any of these elements is has insufficient supply, deficiency occurs. Pay close attention because roses do communicate when this happens.

We would expect that supplying the required nutrients is enough but sometimes these nutrient elements counteract and reacts against each other. Alternatively, they may interact in ways that enhance each other’s effect. This unusual scenario is known as synergism and antagonism between elements.

Calcium is the most antagonistic element while molybdenum is the most synergistic. Keep this relationship in mind when making any fertilizer regime.

At this point, you should be able to compose a feeding regime/recipe with great ease having gone through all the technicalities involved.

Fertigation system

Using an advanced Fertigation system will help you to regulate total amount of fertilizer to apply, fertilizer proportions in the irrigation water, applications duration, and start and finish time. There are three techniques for using fertilizers.

  • Three stage application: It involves starting irrigation without fertilizers. The injection begins when the ground is wet. Injection stops before the irrigation cycle is completed. This allows the fertilizers to be flushed out of the system with the remainder of the irrigation water.
  • Continuous Application: Fertilizer is applied at a constant rate from irrigation start to finish. The amount of fertilizer is injected, regardless of the water discharge rate.
  • Proportional application: The injection rate is proportional to the water discharge rate. There are two types of Fertigation system commonly used namely inline system (direct injection) and indirect injection (less concentrated solution). Before, you settle on one system make sure you think about the maintenance and operational expertise.

For more information on Fertigation system, consult your nearest regional agronomist or you can contact us.
Have we made a fertilizer regime that your roses will love? Let’s meet in the comments as you give us your thoughts


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