How and When to Fertilize Your Christmas Cactus for the Best Blooms

Christmas cacti are low-maintenance and long-lived beauties that show off in a major way just in time for the winter holidays. Often confused for their Thanksgiving and Easter blooming relatives, they all have similar needs. You can fertilize them in much the same way. 

While they don’t have exceptional nutrient needs, they do need some assistance if you want them to bloom to their full potential. When you fertilize, it is just as important as how and with what type of nutrients. 

If you want your plant to put on an extra colorful show next year, you’ve got to fertilize it. Let’s talk about when you should give your Christmas cactus the fertilizer it needs and how to best go about it. 

When to Fertilize a Christmas Cactus

If you’ve gotten close to blooming time, there is little you can do to enhance your Christmas cactus’ blooming cycle. Once this succulent produces buds, it stops actively growing. This is the initiation of its dormancy. 

The best time to fertilize a Christmas cactus is while it is actively growing. If you feed at a time when it is dormant, you risk damaging the roots with an overabundance of nutrients. If it’s not growing, it’s not taking in nearly as much water or nutrients. 

The average growth season for this succulent is between April and October. You’ll notice that while leaf growth stops while your plant is blooming, it will start putting out leaves again mid-spring. That’s when it’s time to start fertilizing again.

How to Fertilize a Christmas Cactus

Determining when to feed is the easy part, but knowing which nutrients your plant needs is extra important. Knowing a bit about how these succulents grow can help you better understand how and how often to fertilize. 

Understand Its Needs

Christmas cacti are not true cacti. While related, they aren’t well adapted to the poor soil and arid conditions of their spiny cousins. Rather than growing in rocky or sandy soil, Schlumbergeras are epiphytes. They are more similar to orchids than cacti in their growth habits. 

These epiphytes grow in shrubs and trees in forest areas of southeastern Brazil. It often rains in these areas, and the air is significantly more humid than that inside your home. The best way to contain them is in a container with good drainage and loose potting soil mixed with large particles. 

Because the most effective potting medium doesn’t hold a ton of moisture, it also doesn’t hold an exceptional amount of nutrients. While Christmas cacti are efficient with those nutrients, they don’t stay in the soil long, so it needs regular fertilizer applications. 

Schlumbergeras need the typical nutrients that are important to most plant life. Nitrogen, potassium, and phosphorus are all important. It also needs several micronutrients to bloom and look its best. Specifically, it needs calcium, iron, and manganese. 

Make Sure the Soil is Right

An important factor in giving this succulent what it needs is providing the right growing medium. Epiphytic roots are highly susceptible to root rot, so drainage is extra important for these. In nature, the exposed roots get plenty of air circulation. In a container, things get more complicated. 

There is also the issue of pH. Christmas cacti prefer slightly acidic soil. Ideally, the pH of the potting media should be within the range of 5.7-6.5. If it falls slightly to one side or the other, it will be fine, but try not to go below 5.5. This will create an overexposure to iron and manganese, which is not beneficial. 

Because they are epiphytes, they need soil that drains quickly, which means it needs to contain some larger particles. Its nutrient needs mean that there has to be some organically rich substrate mixed in.

Commercial succulent and cactus potting mix is a good place to start. If you want a quick, go-to potting soil. This will provide the right combination of organic material and large particles to maintain the right pH and drainage requirement.

If you prefer to mix your own potting media, start with a standard potting mix and add perlite in a 3:1 ratio.

Choose the Right Formula

You can go in different directions when choosing a fertilizer, with the simplest option being a balanced formula. A 10-10-10 or 20-20-20 formula will typically be sufficient for this species. 

The numbers in a fertilizer formula represent ratios of nitrogen, phosphorus, and potassium. Nitrogen is responsible for green growth, while phosphorus helps with photosynthesis. It’s also essential for cell division, and helps the cells store and communicate genetic information. Phosphorus is also responsible for root development, and increases the plant’s resistance to stress. 

Potassium serves some of the same functions as phosphorus, aiding in photosynthesis, and making the plant more resistant to stress. It also controls and regulates the water uptake and distribution of water and nutrients in cells. These are all considered macronutrients, the most vital nutrients for the plant’s survival.

The other option is to choose a formula with micronutrients, and in particular, magnesium. Schlumbergeras have high magnesium needs, so while Epsom salt is typically not a great addition to fertilizing most plants, it may benefit this one. 

In general, Epsom salts are only necessary where soil is poor and depleted. It can actually cause more harm than good in many cases, inhibiting calcium absorption. Adding too much magnesium to the soil can be detrimental, so this practice is somewhat controversial. 

In the case of your Christmas cactus, small amounts of epsom salt fertilizer may help this plant’s needs if the soil is deficient. To deliver a small amount, use a mister filled with water and a few tablespoons of Epsom salt dissolved in it. Don’t worry about this if you are using a fertilizer with micronutrients added. 

Time it Effectively

Finally, timing is important. We talked about when time of year you should start and stop fertilizing, but here, I want to discuss frequency. It’s always better to under fertilize than to overdo it. Too much of a good thing, in this case, is a bad thing. 

The most concerning result of over-fertilizing is desiccation of the roots. This is sometimes referred to as root burn. The buildup of minerals on the roots interferes with water uptake, and the whole plants suffers as a result. You may see this result in tip burn or dieback of the leaves. This can ultimately lead to whole plant death. 

Under-fertilizing may not result in maximum growth and flowering, but it’s unlikely to kill the plant. It will get a fair amount of nutrients from the soil as long as the pH is right. The pH of the soil is what causes the nutrients to break down in a way that is useful for your Christmas cactus.

To avoid giving your Christmas cactus too much—while still maximizing the growth and blooming ability—fertilize once per month. I’m a fan of liquids over granular formulas, as they are more readily available and work faster. It can be more costly, but we aren’t worried about a large space, so it’s not that great a difference. 

Follow the directions on the fertilizer package in terms of delivering the right amount. Because this is not a heavy feeder, you can dilute to half strength if you’re concerned about root desiccation. 

Apply your chosen formula once per month until mid fall. Once the buds pop out, your plant is preparing for dormancy, and won’t produce any new green growth until spring rolls around. Let your Christmas cactus rest during the winter, and do what it does best, bloom!