The best succulent fertilizer for cactus and other succulents will be 1) organic 2) low on NPK, especially nitrogen 3) include beneficial soil microbes such as probiotics and mycorrhizae 4) contain humic acids and 5) finally it should be a slow release blend. We did find a brand that met all those important requirements. You can read our full succulent fertilizer review or directly examine our top recommendation Dr. Earth Root Zone.
Many Succulents Do Need to be Fertilized
It is true that many succulents will never need to be fertilized and they will be perfectly healthy. Often, however, applying a little fertilizer will encourage succulents to produce vibrant leaves and more flowers with dazzling colors. Applying a high quality fertilizer will not just make succulents look better, they will actually be much healthier and will often live longer.
What Do the Numbers Such as 10-20-10 on Fertilizers Mean?
Commercial brand fertilizers are often labeled with numbers such as 20-20-20. These numbers follow a national standard and are sometimes referred to as the “fertilizer grade.” Each number is a value that represents the percentage of the available individual ingredients. The order of the numbers represent nitrogen, phosphorous and potassium. Sometimes these three macro-nutrients are referred to as NPK which stand for the (N) nitrogen, (P) phosphorus and (K) potassium.
So a balanced fertilizer of say 10-10-10 would mean that there were equal proportions of the nitrogen, the phosphorus and the potassium. A fertilizer with a grade of 5-10-5 would have a 5% portion of nitrogen, a 10% portion of phosphorus and a 5 % portion of potassium. The remaining weight in the bag of a good quality fertilizer would be other filler that might include compost, soil, and other specially selected nutrients.
Nitrogen, phosphorus and potassium are all essential for the growth of every type of plant. How does each of these nutrients help succulents?
- Nitrogen (N) – is primarily responsible for assisting the growth of the leaves.
- Phosphorus (P) – is primarily responsible for healthy root growth as well as the optimal development of fruit and flowers.
- Potassium (K) – is critical for improving the overall biological functions of the plant.
What Succulent Fertilizer Ratio of NPK Should I Look For?
Many succulents do not need a special blend but do well with a highly diluted strength of an all-purpose balanced fertilizer. That can still be risky for some sensitive succulents. Dr. Earth has a great all-purpose fertilizer called “Life” with an NPK of 5-5-5. It can be used for all types of plants including succulents.
However, the Dr. Earth “Root Zone” fertilizer is even more targeted for cactus and other succulents. It uses fish bone meal, mycorrhizae and other superior ingredients in the blend and has an NPK grade of 2-4-2 which will produce outstanding results.
You might be thinking, “Isn’t that NPK so low that it won’t have much effect at all?” Remember that succulents are drought resistant and are adapted to thrive with a minute amount of nutrients. Shocking them with too much fertilizer is much worse than using no fertilizer at all. With a high quality organic fertilizer that has a low NPK you do not need to fear that it will be harmful to your plants. Also, no dilution is necessary like it is with chemical fertilizers. This eliminates the need to guess at the right fertilizer to water ratio and the messy task of diluting the overly strong chemical product.
When and How Often Should I Fertilize Succulents?
If you are unsure how often or when to fertilize a specific succulent there is a general rule of thumb you can use. Fertilize at the beginning of or just before the start of the growing season.
The growing season for most succulents begins in the late spring or summer. Because of this, mid to late spring would be the best time to apply a fertilizer. For succulents with a winter growing season it is best to apply fertilizer in the fall. Fertilizing just once a year is just right for most cactus and other succulents. If it does not appear to be enough then you can fertilize again in 2-3 months.
Growing Season is Summer = Fertilize in Late Spring
Growing Season is Winter = Fertilize in Late Fall
If you are using a high quality organic fertilizer, don’t worry, the timing of the application is usually not critical. The succulents will naturally take up and absorb only what benefits them at the time. The remaining nutrients will be utilized later when that plant needs them more. If you are using a chemical fertilizer, however, be careful to never fertilize your succulents just before or during their more dormant times of the year.
Many growers also find that adding a good quality succulent fertilizer when transplanting potted plants produces good results.
Most outdoor succulents growing in the ground will survive without ever being fertilized. They too, however, will benefit from occasional fertilizing if the soil is poor or when you are attempting to increase flower production. Some people find that their cacti flower like crazy after adding just a small amount of succulent fertilizer.
Applying too much fertilizer or doing it too often may cause some succulents to burn or even die. Many chemical fertilizers are simply far too potent for succulents. The NPK is too high and so the plant is shocked and overwhelmed by too much fertilizer applied too suddenly. If you must use a non-organic fertilizer the University of Minnesota Extension recommends using a fertilizer “that is higher in phosphorus than nitrogen, diluted to half the recommended rate.”
If the Primary Goal is Optimizing Flower Production
If you are specifically trying to increase flower production you may want to try the Dr. Earth “Flower Girl” blend Instead of the “Root Zone”. Yes, the Root Zone is the best fertilizer for succulents but the Flower Girl has been specially developed to encourage flower production. It has an NPK of 4-10-7 so it has a much higher optimal dose of phosphorus for abundant flower growth. Test it sparingly when using it on your more sensitive succulents and just in case you may even want to dilute it a little bit first.
If neither of these Dr. Earth products is available you can cautiously try a fertilizer advertised for tomatoes since these typically have a higher ratio of phosphorus which flowers love. Try to find one with an NPK around 8-15-8 or lower and dilute it to ¼ strength.
Why is Humic Acid Beneficial in a Fertilizer?
Humic acid and fulvic acid act as chelators turning minerals into simple organic compounds. These compounds are then much more available for the succulent’s nutritional needs. Additionally if there are unwanted toxins in the soil, humic acid will inhibit absorption by the plants. Most good quality soil will already have at least some humic acid present but the best fertilizers include it for additional supplementation.
Why are Probiotics and Mycorrhizae so Beneficial?
The highly beneficial soil microbes such as mycorrhizae and probiotics help keep the soil “alive”. They will keep growing and symbiotically help the soil to actually keep improving over time. Most growers have seen such great success that they would never consider buying a potting soil or fertilizer that did not contain these living microbes in the product.
Never use a fertilizer developed for lawn care on your succulents. These fertilizers may be great for grasses but they are extremely harmful to succulents since they are very high in nitrogen. The high nitrogen content greatly speeds up and enhances the vegetative growth which is counterproductive for succulents.
Why is the Best Succulent Fertilizer Organic?
Much lower doses of the NPK are needed when the fertilizer is organic. A good quality organic fertilizer will go a long way when used to boost cactus and other succulents. The nutrients stay in the soil and symbiotically work together to feed the soil and the plant. The beneficial compounds in the organic fertilizer are taken up by the plant as they are needed in a slower and more natural way. Chemical fertilizers are often too much and too fast acting for any type of succulent. As mentioned earlier, if a chemical fertilizer is your only option, at least make sure that it has a very low NPK and that you dilute it quite a bit.
How Long Does the Fertilizer Stay in the Soil?
With many chemical and non-organic fertilizers the essential components, especially the nitrogen and potassium, may be leached out after the first watering or two. Even when it is not deeply watered the nutrients may be ineffective within weeks. The added phosphorus will likely stay longer in good quality soil but it is not as effective if the nitrogen and potassium have already leached out.
Unlike many other plants you do not need to be obsessed with a critical schedule for fertilizing succulents. You may not need to fertilize your succulents at all, but if you do, once or twice a year in the growing season is all you usually need. Try not to be too concerned about the expense since you will be fertilizing infrequently and it takes just a very small amount to reap wonderful benefits. We recommend using an organic cactus and succulent fertilizer like Dr. Earth Root Zone for the best results.