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7 Mistakes That Make Cactus Not Grow (And How To Fix)

Cacti stand out as some of the most intriguing plants, sparking a lot of curiosity. More and more plant enthusiasts are choosing cacti as indoor plants. However, growing a cactus outside its natural habitat can be challenging.

The lack of sunlight, too much water, and not respecting its dormancy period are key factors that hinder a cactus’s growth. To help a struggling cactus, ensure it gets at least 5 hours of direct sunlight daily, water it only when the pot’s soil is totally dry, and keep it in a well-ventilated room with moderate humidity.

1. Overwatering

Cactus not growing because of root rot.

Cactus not growing because of root rot.

A common misconception is treating cacti like typical houseplants, leading many to water them regularly, such as weekly. This approach can be harmful, as cacti sitting in moist soil will quickly develop root rot.

Cacti are adapted to environments where rain is scarce for long periods. Failing to mimic these dry conditions at home can result in a cactus that struggles to thrive.

To help your cactus:

  1. Start by removing any rotten roots, then replant the cactus in fresh, sterile soil designed for succulents.
  2. Apply a solution of hydrogen peroxide to the cut areas to disinfect.
  3. Water the cactus only when the soil is completely dry.
  4. Ensure the pot has ample drainage holes to avoid water accumulation.

2. Not Enough Sunlight

Not enough direct sun

Cactus not growing because of not enough direct sun.

Cacti are native to deserts, thriving under intense sunlight without any shade. Replicating these conditions indoors can be challenging, but it’s important to ensure they get several hours of direct sunlight daily.

Without enough light, a cactus may become elongated and slender as it stretches towards the light source. It will rely on its stored energy for growth, and once that’s depleted, growth will halt.

To help your cactus:

  1. Gradually move it to a spot that gets at least 6 hours of direct sunlight each day, increasing the exposure by 1 hour weekly.
  2. An ideal spot is near a south-facing window.
  3. In the absence of sufficient natural light, consider using artificial lighting to supplement.

3. Dormancy Period

Cactus not growing because of dormant in winter.

Cactus not growing because of dormant in winter.

The dormancy period is crucial for plants, serving as a time for rest and energy storage in anticipation of the next growth season. During this time, plants typically do not grow. Cacti, in particular, enter dormancy twice a year.

The first dormancy phase occurs in winter, coinciding with reduced sunlight. This slowdown in growth prevents the cacti from becoming elongated and weakened. This phase can begin around October or November and last until March.

The second phase is the summer dormancy, triggered by the intense, scorching sun. To avoid tissue damage and excessive water loss, cacti also reduce their growth rate during this time, usually for 30-40 days in the peak of summer.

This means cacti grow more slowly compared to some other plants, like echeveria. Patience is key with these resilient plants, ensuring they stay healthy and vibrant.

To help your cactus:

  1. Cut back on watering slightly during the summer dormancy.
  2. In winter dormancy, wait for the potting soil to dry out completely before watering again, typically every two weeks.

4. Poor Air Circulation

Poor air ventilation during hot weather

Cactus not growing because of poor air ventilation during hot weather.

Like all plants, cacti thrive in clean, fresh air and cannot stand still, humid conditions, which could lead to fungal infections. Their water-rich structure makes them particularly susceptible to rot.

Moreover, if it’s very hot and the cactus is near a window with inadequate ventilation, it might start to wilt.

To help your cactus:

  1. Ensure the room where your cactus is has good airflow.
  2. Avoid placing your cactus in the bathroom, as it’s typically too humid.
  3. Keep the cactus away from air conditioners, fridges, and similar appliances that could disrupt its ideal growing conditions.
  4. Also, avoid spots with cold drafts which can harm the plant.

5. Pot and Soil Issues

Cactus not growing because of soil.

Cactus not growing because of soil.

The issue arises when the pot is too large. A cactus in an oversized pot faces soil that remains wet for extended periods, leading to potential root rot. The pot size and soil volume should be adequate to avoid root binding without being excessive.

To help your cactus:

  1. Trim away the rotten roots and apply hydrogen peroxide to the affected areas to disinfect.
  2. Repot the cactus in fresh cactus-specific soil that’s low in organic content but high in drainage material, like perlite.
  3. Choose a pot that’s just slightly larger than the cactus itself, ensuring it has 4-6 large drainage holes to prevent water accumulation.

6. Nutrient Deficiencies

Lack of nutrients

Cactus not growing because of lack of nutrients.

Often, a cactus’s growth is hampered by a lack of nutrients in its soil, which is actually consistent with their natural habitat. Deserts, where cacti originate, are low in nutrients, explaining why cacti don’t thrive in organically rich soils.

Cacti are adapted to grow in lean, stony-sandy soils, leading to their characteristically slow growth rate. Indoor conditions can further slow this growth, making it seem like the cactus isn’t growing at all, when in reality, it’s just growing very slowly.

To help your cactus:

  1. Fertilize your cactus annually at the start of its growing season.
  2. Opt for a slow-release fertilizer specifically formulated for cacti or succulents.
  3. Steer clear of compost and other rich organic fertilizers.
  4. Refrain from fertilizing during the cactus’s dormancy periods.

7. Transplant Shock

Cactus not growing because of transplant shock.

Cactus not growing because of transplant shock.

Just like all plants, cacti are always growing and evolving, and eventually, they’ll require more room to expand. Without timely repotting, their roots can run out of space, halting growth until the plant is moved to a larger pot.

However, it’s important to note that plants, including cacti, can undergo stress after being repotted, known as transplant shock. A common sign of this is a prolonged period where the cactus doesn’t grow.

To help your cactus:

  1. Take care not to harm the roots or the plant itself during the repotting process.
  2. Always use a high-quality succulent mix suited for cacti.
  3. Limit direct sunlight to 2-4 hours daily post-transplant. As your cactus starts showing signs of growth, you can gradually move it back to its original spot.