How to Plant, Grow, and Care for Old Lady Cactus
Are you a succulent aficionado looking for a fun new cactus? The old lady cactus is a wonderful species that's easy to care for and produces beautiful flowers. Gardening expert Melissa Strauss discusses the care and keeping of this interesting cactus.

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Cacti are fascinating and beautiful if you don’t mind handling your plants gingerly. Their low-maintenance needs make them great for beginners and plant lovers of all kinds. As an added bonus, most of them bloom well, even when you keep them indoors.
With at least 2,000 species of cactus to choose from, it can be difficult to narrow it down. Each one is more fascinating than the next. With it’s fun name and quirky appearance, it’s no wonder that the old lady cactus is among the more popular cacti around.
Old Lady Cactus Overview

Plant Type
Cactus
Family
Cactaceae
Genus
Mammillaria
Species
Hahniana
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Native Area
Mexico
Exposure
Full sun to partial shade
Height
Up to 12”
Watering Requirements
Low
|
Pests & Diseases
Root rot, stem blotch, longhorn beetles, mealybugs, spider mites
Maintenance
Low
Soil Type
Loose, sandy, well-draining
Hardiness Zone
9-11
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What Is It?

The old lady cactus is a small, clump-forming species that holds a prestigious Award for Garden Merit from the Royal Horticultural Society. This mark of a quality garden plant goes back 100 years. It is awarded to the finest plants that display ideal performance, particularly in the UK. Its unique appearance makes it popular among collectors, who love the species for its ease of care and beautiful flowers.
Characteristics

The name of this cactus tells you what you want to know! This sweet little old lady starts off globular and grows taller over time into a cylindrical shape. The stems reach up to 12 inches tall and four inches wide. They can be solitary or form clumps over time.
The defining characteristic of this cactus is the spines. Covered in small white spines, it has both bristly spines and soft white ones that resemble fine white hairs. These fine white spines cover the plant, acting as protection from the sun, and they make the stems look like a white-haired head from a bird’s eye view.
This cactus also has a great blooming habit. The flowers form in late winter and early spring, blooming through the spring and into early summer. They are bright pink and funnel-shaped, and they form a crown around the top of the stems. They give the appearance of a flower crown on the head of a white-haired lady, and they are beautiful!
Native Area

Native to Mexico, you’ll find this in cultivation in parts of Southern North America, Central America, and even some parts of South America and the Caribbean. It typically grows on sloping hillsides in arid climates with hot days and cool nights.
Planting

Like most cacti, this one likes to be pot-bound. You will want to plant it in a container that is not much larger than its delicate root system and avoid repotting frequently. In fact, you can keep it in the pot it comes in for several years and simply place that one into a more decorative container if you like.
Make sure that whatever container you plant this in has ample drainage holes. Soggy roots are a cactus killer. If you place the plastic pot in a decorative one without holes, remove it from that decorative container to water it. This enables the water to flow freely out the bottom.
How to Grow
Like most, this cactus is easy to grow and care for. It prefers some neglect, as it is easy to love it to death. If you give it the right amount of care, this slow-grower will live for a long time.
Light

This plant is flexible with how it takes sunlight, but it needs a significant amount. You can place it in direct sun or bright indirect light as long as it gets a minimum of four to six hours daily. The fine white hairs that cover these stems act as a type of sunscreen, protecting them from sun scorch.
Water

Water this plant sparingly, as over-watering is deadly. It has fine, delicate roots that succumb to root rot in a brief period if you allow the soil to remain moist at all times. Make sure to allow the soil to dry between waterings.
During the growing season, water about once every two weeks. Allow the water to run out the bottom of the container and drain thoroughly. In the winter, it will go dormant, at which time you should drastically reduce watering. Cut back to just once per month during this time.
Soil

Commercially sold cactus potting mixes are available at most nurseries and hardware stores. These are pre-mixed and contain a mixture of large particles and soil that drains quickly and doesn’t remain wet.
If you prefer to customize your own potting mix, start with high-quality potting soil, coarse sand, and perlite or pumice. Combine three parts of soil with two parts of sand and one part of pumice or perlite. Your mixture should be light and airy.
Temperature and Humidity

During the growing season, keep it warm. This cactus tolerates and prefers hot weather. Temperatures between 70-100°F (21-38°C) will keep it happy and thriving. This means that you may want to put it outdoors during the warmer months, but keeping it in a sunny window in the home will suffice, too.
In the winter, in order to signal blooming, you’ll want to reduce the temperature. Lower temperatures and fewer daylight hours let this old lady know that it’s about to be blooming time. Leaving it outdoors in the fall for a few weeks will do the trick, but don’t let it freeze. These are tolerant down to about 40°F (4°C) but don’t leave it out if it’s going to get colder than that.
Like most cacti, humidity is not a major concern here, although you want to avoid high-humidity conditions. The normal level inside your home should be fine. I would keep this plant out of the bathroom. Too much moisture in the air can lead to fungal issues.
Fertilizing

Succulents and cacti don’t require much fertilizer, but you can give a few applications yearly. Only fertilize while the plant is growing, as fertilizing a dormant one will burn the roots. Use a fertilizer formulated for this type of plant and apply once or twice in the spring and once in the summer.
Maintenance

There is not much maintenance involved in caring for this plant. Once the flowers fade, you can deadhead by removing the spent blooms to clean up its appearance. You won’t need to prune it, and re-pot only when it outgrows its container.
Propagation

The most common and effective propagation method is by cuttings. I would personally wait until your plant creates an offset before doing so, as you’ll end up having to cut the main stem otherwise. Once your plant has begun to clump, feel free to take cuttings.
- Choose a healthy segment of a stem to cut from, and use a clean, sharp tool to cut a segment of about two to three inches. This will ensure the cleanest cut, which will heal fastest, preventing disease. Alternatively, you can twist an offset and pluck it from the mother plant with some roots attached.
- Set your cuttings aside for a few days in a dry, dark spot. You want the cut to heal over and form a callous. This is an important step, as the bottom of the cutting is likely to rot if you don’t allow it to callous.
- Use a pot with excellent drainage and fill it with a damp potting mix, the same type that you formulated for the parent plant.
- Place your cutting in a bright location outside of direct sunlight. You want to provide about six hours of bright indirect light daily.
- Water sparingly, especially in the early stages, as there won’t be much root structure to absorb the water. Then, the soil will remain wet, and your cutting will rot.
Common Problems
This is a low-maintenance plant, and one that doesn’t encounter a great deal of problems, but there are a few things to look out for.
Pests

Longhorn beetles are the most prevalent pest to come after this cactus. These large, scary-looking insects can do a lot of damage, but they are easy to identify and remove. So, there is little chance of them destroying the plant.
If you see one of these guys on your old lady, you can rinse it off outdoors with a stream of water or use your fingers to pick it off. Personally, I’m a bit squeamish about insects. I have a hard time with hand removal, but with a pair of gloves, it’s not terrible.
Other potential pest issues come from spider mites and mealybugs. If you’ve ever dealt with these, you know that one is a much bigger problem than the other.
Mealybugs are damaging, but they are easy to see and identify. Sadly, their waxy coating makes most methods ineffective. Use a 70% or less alcohol-soaked cotton swab or pad and gently wipe them off. Make sure to rinse the plant afterward to avoid damaging tissue with the alcohol.
Spider mites are more complicated because they are so hard to identify and treat. If you suspect these are present, inspect the plant for their fine webbing. The mites are typically too small to see, but their webs are visible.
Neem oil and insecticidal soaps are effective in getting rid of spider mites. A strong stream of water can help knock down populations. If you want to try that before treating, then there are fewer insects to deal with.
Diseases

Most of the diseases that affect this cactus are fungal in nature. This is nearly always the result of poor watering practices or too much moisture in the air. Overwatering is the biggest mistake you can make when caring for any cactus or succulent.
A squishy stem is an indication that the plant is getting too much water. It’s a short jump from this to root rot, which is usually fatal. If you notice the stems becoming soft, hold back on watering and make sure that you are allowing the soil to dry completely between waterings.
If you notice a foul smell from the soil, this indicates a severe case of root rot. There is little chance of coming back from this, but you can try.
Re-potting is the best way to salvage a plant with root rot. Remove it from its continer and gently work the soil from the roots. Use a small, clean, sharp pair of scissors to cut away all the mushy, rotted root tissue before planting in new fresh potting mix. Water sparingly going forward until you notice the plant rebounding.
Other fungal and bacterial diseases can creep in when there is an overabundance of moisture in the soil or the air and not enough sunlight or air circulation. Prevention is the best way to deal with these. Keep the air flowing in your space, and keep your cactus in a space with drier air.
Frequently Asked Questions
What can you plant it with?
Add your old lady cactus to a rock garden or planter with other succulents or cacti. It will do best near other plants that have similar needs.
Is it safe for pets?
This cactus is not toxic to ingest, and in fact, it produces edible fruit. However, it is dangerous for pets and people to eat the stems, as they ar covered in sharp spines.
How do you overwinter your old lady cactus?
You’ll need to bring this one indoors for the winter. While it likes slightly cooler temperatures in winter, it is not frost-tolerant.