Why Is My Cactus Turning Light Green

Did you buy a cactus because you heard they’re low maintenance? That’s right! They’re the easiest plants to keep alive.

However, being low maintenance doesn’t mean they won’t face any problems. A cactus can turn light green for numerous reasons, like nutrient deficiencies or lack of sunlight.

Here are some reasons why your cactus is turning light green, what to do, and how to avoid it:

Lack of Sunlight

Most cacti come from harsh, arid environments which get a lot of sun. It’s best to imitate the conditions of its natural habitat as much as possible to keep a plant happy.

When we fail to do that, the plant suffers.

If a cactus doesn’t get enough sunlight, its growth becomes stunted, its color lightens, and its spines soften. This phenomenon is called etiolation.

Check if your plant is getting enough sunlight if you notice that:

  1. The top part or all of your cactus is turning light green
  2. The cactus is growing much thinner.
  3. The soil takes over two and a half weeks to dry out.

What do you do if your cactus plant is turning pale because it’s not getting enough sun? You’ll have to move it.

Just place it in a sunnier spot. If you do not have a sunny spot, try putting it outside. If you live somewhere where it’s always mostly cloudy, invest in some grow lights.

You can significantly grow your plant collection if you buy grow lights as you control the light source. You will no longer be restricted by the amount of light you’re getting or the space on the shelf by the window.

Be careful because some cacti do not need direct sunlight. They rely on indirect sunlight, like the Christmas Cactus. Their leaves and stems will burn if placed in direct sunlight. If your cactus needs indirect light, you can still give it more sun. You can place it in a shady spot outside or with dappled light. That way, it can get more indirect sunlight.

Nutrient Deficiency

When we don’t get enough nutrients, we get sick, as do plants. If you’re absolutely certain that your cactus plant is getting enough sunlight, it may be because it lacks enough nutrients.

Your cactus plant could need more nutrients because:

You Don’t Fertilize it

While cacti thrive when you water and care for them less, that doesn’t mean you shouldn’t fertilize them.

Like all other houseplants, the soil in the pot doesn’t have any source of replenishing its nutrients, and the cactus can’t spread its roots further to get new nutrients, either.

So, we need to add fertilizer to ensure the cactus and all other houseplants get enough nutrients to grow. 

You can fertilize your cactus as little as once a month or every time you water it.

You Don’t Use the Right Fertilizer

Maybe you do diligently fertilize your cactus plant. It could still develop a nutrient deficiency. If you do not use the right plant food, your cactus may miss out on an important mineral.

Try to get fertilizer labeled for cacti with even amounts of potassium, phosphorus, and nitrogen. Something with a 10-10-10 NPK ratio would be ideal.

Roots are Unhealthy

Think about it. The roots carry nutrients from the soil to the rest of the plant. How would the plant get enough nutrients if there’s something wrong with them?

It doesn’t hurt to check if you think there could be a problem with the roots. Periodically checking the plant roots keeps you on top of any problems your plant could face anyway.

Root Rot

Overwatering or using the wrong soil could cause your roots to develop rot. Rotted roots are blackened and squishy. To check the health of your cactus roots, remove them from the pot and give them a good look over.

If the roots are rotted, cut them away and re-pot your cactus.

If it survives the shock and continues to grow, then great. Otherwise, you can use it to propagate new cuttings.

Root Bound

If the plant outgrows its pot, it will become root bound. You can tell your cactus is root bound if you see roots coming out of the drainage holes or the top of the pot.

Even if you don’t see these signs, taking the plant out of the pot will be obvious.

When a plant is root bound, its roots are matted and fill most of the space in the pot, leaving little room for soil.

To fix this, trim the edges of the roots and move the plant to a deeper pot. However, if you use a far too big pot for your plant, the water in the soil won’t be used timely, making your plant waterlogged.

That’s why moving it to a pot at most 30% or one-third bigger than the last one is prudent.

Pest Infection

If pests are attacking your plant and stealing its nutrients, it’s tough to expect it to grow or stay a deep shade of green. When buying plants at the store, check them closely to ensure they don’t have any pests.

Once you bring it home, keep it quarantined from your remaining plants for a few days until you’re certain.

Cactus bugs, spider mites, mealybugs, and more can attack your precious cactus.

To avoid bugs getting to your cactus, place it behind a glass window so bugs can’t get inside. Use an organic pest killer or a mixture of organic insecticidal soup and spray the surrounding area of the plants.

If you see any pests, remove them by hand, wearing gloves. Place your plant away from others and apply insecticide according to the instructions on the package.

Over Watering

If you over-water your cactus, it will become soft. The access water in the plant tissue leads to rot. When plant tissue rots, it can turn different colors.

It could be yellow, brown, black, or a lighter shade of green.

Wait to water your cactus until the soil has completely dried out. Cacti are drought resistant; don’t mind if you’re behind on watering them. However, if you water it while its soil is still moist, it does mind.

If unsure, take your finger and poke it a couple of inches into the soil. If you feel moisture, you shouldn’t water it yet.

If your cactus is overwatered, you can quickly change the soil for fresh dry soil mix if the soil is still moist. Allow the cactus to harden again, and give it extra sunlight.

If any parts have changed color due to rotting, you must cut them off with a sharp knife or gardening shears.

New Growth

Is your cactus growing just as fast and showing no negative signs? The roots are healthy, it gets plenty of suns, and you use the right fertilizer regularly. But the tips or top of your cactus appear to turn light green.

This could also be the new growth on your cactus. It isn’t rare for newly grown parts of a plant to be lighter in color than the rest of the plant. If you’ve checked your plant for everything else and it looks healthy, it’s likely nothing but new growth.

If that’s the case, that part of the cactus will match with the rest in due time. That’s right, you’ve done nothing wrong, and your cactus is doing fine.

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While Cacti are the easiest plants to care for, they also face problems. Your cactus could turn light green due to a lack of sun or nutrients, a pest infection, or overwatering.

Luckily each of these problems has a simple solution. If you’re already doing everything right and your cactus looks healthy, the light green part could be new growth.