The Christmas cactus is one of the most interesting plants to grow indoors. As you know, this holiday cactus rewards with vibrant color in the dead of winter. Many gardeners struggle to grow a bigger Christmas cactus with no success.
This plant won’t thrive when its native growth conditions aren’t met. Overcrowded roots, nutrient deficiencies, inadequate lighting, poor watering, and insect pests may stunt the plant’s growth.
Why is my Christmas cactus not growing?
If your Christmas cactus is not expanding then you need to look into the following issues.
1. Overcrowded roots
Typically, holiday cacti like to be root bound – they thrive when roots are crowded in a small planter. However, in time the roots get too constricted to stay healthy. When overcrowded, the cactus roots stop absorbing nutrients, air, and water as needed thus affecting the whole plant.
Root bound may not be easy to detect from above the soil but symptoms may show as those of underwatered Christmas cactus. The plant may wilt, turn purple, or have stunted growth. Severely crowded roots may show above the soil or poke through the drainage holes.
How to check
If you suspect compacted roots, remove the plant from the pot and inspect the root ball. Simply grab the plant by the main stem and lift it up while tugging down the pot. A severely root-bound plant won’t come off the container easily especially when roots are strongly entwined through the drainage holes.
You may have to use a long serrated knife to cut around the plant for easy removal. If the pot is flexible, try to squeeze around it in different directions to loosen the root ball. Breaking the pot may also be an option if everything else fails to work.
If the plant is extremely root bound, you’ll notice a dense network of roots forming a solid mass with little traces of soil between them. In that state, roots will struggle to breathe and take up nutrients or water from the soil.
How to fix
When your Christmas cactus is unhealthy due to overcrowded roots, you only have a few options to save the plant. You can either repot the cactus in a slightly bigger container or divide the plant into two or more separate portions and replant them in different pots.
If you decide to repot the plant, then start by untangling the roots to help the plant recover easily from the problem. You may also prune a few roots that extended out of the container. Be sure to use well-drained soil formulated for succulents and a pot with drainage holes at the bottom.
2. Nutrient deficiencies
Holiday cacti plants use a lot of energy when blooming. During active growth, the Christmas cactus keeps storing sugars and important nutrients for this purpose. When fall comes, all the stored sugars are usually converted into energy necessary for the formation of flower buds, and in the end, none is left for growth.
Nutrient deficiencies in holiday cacti may also occur from improper uptake by the crowded roots. Some nutrients may also not be available to the plant when the soil pH shifts. Underwatering may also make it difficult for roots to absorb and transport nutrients to where they are needed in the plant.
How to fix
It may be difficult to tell the difference between a nutrient deficiency and other Christmas cactus problems as symptoms seem to appear the same. The best way to check for lack of nutrients in the soil is to conduct a soil test, explains the West Virginia University Extension. You may use a do-it-yourself test kit or take a sample of the soil from your county’s university extension agent.
To replenish your Christmas cactus nutritional needs, fertilize it monthly from the time new growth starts in April to the end of summer in August. Additionally, apply Epsom salt solution mixed at one teaspoonful per gallon of water, in the same growth period but not on the same week as fertilize.
Do not feed your Christmas cactus during the blooming season. It may cause the plant not to set flower buds or make the blooms wilt and fall off. Just water the plant whenever the soil feels dry and keep it in uninterrupted darkness for 12 to 14 hours daily for six to eight weeks to stimulate blooming.
3. Insufficient light
Light is a very important requirement in every green plant. The resource is useful in the process of photosynthesis where plants make their own food. Without adequate light, carbohydrates cannot be manufactured resulting in stunted growth, wilting, and death of the plant.
When grown in directional light, plants will always bend towards the brighter side. They will also compete in growth as they try to tap the prestigious resource. Keeping your plant in darkness is a sure way of killing it. Fortunately, you can still use artificial lighting in areas without sunlight to satisfy your plants’ needs.
How to fix
Unlike the desert cactus, the Christmas cactus and its cousins the Thanksgiving cactus and Easter cactus thrive in bright indirect light. Exposure to direct sunlight will result in sunburn on their soft stems. In their native home, these plants are usually protected from the sun by the dense forest cover.
North or east-facing windows are preferred locations for Christmas cacti. You may take your Christmas cactus outside during summer to enjoy the warmth and humidity. But be sure to keep it protected from direct sunlight and flooding waters. A covered patio or porch can be a perfect spot.
4. Inadequate watering
Water is also an essential raw material in the process of photosynthesis. It also enables nutrients and sugars to be translocated to where they are needed in the plant. Plants without sufficient watering will stop growing and wilt. The plant may also die in prolonged dehydration due to halted metabolism activities.
How to fix
Holiday cactus thrives when there is constant moisture in the soil but does not like wet conditions. Watering too often may cause root rot, a condition that can kill the plant in a matter of days, explains the University of New Hampshire.
Watering should be done when the top inch of the soil feels dry to the touch. Do not let the plant sit in excess of the water that collects on the saucer after the watering. It may be reabsorbed into the soil through the drainage holes to make the soil soggy and harmful to the cactus roots.
It is also necessary to mist your holiday cactus when the air is dry. You can simply place the plant on a pebble tray filled with water and it will enjoy some humidity as the water evaporates. Additionally, keep the plant away from dry air sources like fireplaces, open windows, and boilers.
5. Insect pests
Pests are a great threat to the health of any plant. Mealybugs, scale, spider mites, and fungus gnats are common pests on Christmas cactus. They usually decimate new growth on the plant as they suck the sap. This results in open wounds where water or pathogens may enter the plant.
The introduction of new plants is a leading source of pests in houseplants. Locating them may not be easy as they usually hide in tight spots. By the time you start seeing bugs on your plants, they are truly widespread and the damage they have caused is beyond imagination.
How to fix
If you discovered pests on your plant, wash them off with a strong strand of water from a hose. Dab visible bugs with rubbing alcohol on a cotton swab. Be careful as the use of too much alcohol may damage the soft parts of stems or leaves. Insecticidal soaps or agricultural oils can also be used on pests as directed by the manufacturer.
New plants you bought or gifted should be isolated and examined for any potential pests or infections. Regular inspection of your houseplants can also help in controlling pests before they spread and become a threat to your plants.
Taking care of a Christmas cactus plant isn’t difficult, you simply need to grow it in well-drained soil, provide bright indirect sunlight, and fertilize it during its active growth and water when the top layer of the soil feels dry. The plant will bloom in cool temperatures preferably when daylights are shorter.
My name is Diane M Lewik, and I am the founder of this website. I am a degree holder in plant biology from the University of California – Berkeley. Over years, I have cultivated a vast collection of succulents and I have learned a great deal about how to grow and care for these unique plants.