The Old Man of the Andes Cactus Indoors (Oreocereus trollii)

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Plant Details

Category: Houseplants
Light: Bright Light
Bloom Season: Spring, Summer
Height: 2-3' / 
0.6-0.9m
Space: 10-12" / 
25-30cm
Zones: 10, 11
Lowest Temp: 30° to 40°F / 
-1° to 4°C
Colors:

Basic Care

Does best in light, well-drained soil. Allow soil to dry between thorough waterings. Limit water during winter months when plant growth slows. Apply a balanced liquid fertilizer monthly during active growth. Wear protective gloves when handling; spines can cause injury and tiny bristles are difficult to remove from skin. For best growth, plant in an unglazed terra-cotta pot. The porous clay allows some water to evaporate away so there is less worry about overwatering.

Water

Allow soil to dry between thorough waterings.

Soil

Light, well-drained soil.

Feed

Apply a balanced liquid fertilizer when plant is in active growth.

grows upright

Grows Upright

Slow Growth

Sun Loving

Containers

hedges

Hedges

Features

The Old Man of the Andes cactus is native to mountainous regions of Bolivia and Argentina. Its common name is a result of its soft covering of white spines that resemble the hair of an old man. These hairs help keep the cactus cool during the day by shading its skin from the scorching sun. At night the hairs insulate it from frosts that can be common in the mountains. In nature the Old Man of the Andes can take years to bloom so it is unlikely to produce flowers when kept as a houseplant. Potted plants grow slowly so this is a cactus that’s easy to contain.

Uses

Perfect for all kinds of containers. May be displayed outdoors in warmer weather. Great near a sunny windowsill in a home or office. A window with a southern or western exposure is ideal.

The Old Man of the Andes Cactus Indoors (Oreocereus trollii) Care Guide

Start with a good quality, commercial potting soil for Cacti and Succulents. That will ensure that the soil is sterile and pest-free. Many are available with a mild starter fertilizer in the mix. If you choose to make your own soil mix, combine equal parts sand and general purpose potting soil.

Select a container with a drainage hole or be prepared to drill holes for drainage if there are none.

Prepare the container by filling with potting soil up to 2” (5cm) from the rim of the planter. Make a hole in the center of the soil large enough to hold the root ball of the plant.

If the plant is spiny be sure to wear gloves for protection. Rubber gloves should be fine if handling small-spined plants but if the plant has long or sharp needles, leather gloves offer more protection.

Small plants may be safely moved using kitchen tongs. For moving larger plants, a good method is to wrap the plant with paper towel or tissue paper. For exceptionally large or spiny plants follow with a layer of newspaper or wrapping paper for extra protection. Wrap gently, not too tight, so as not to crush the spines. Tape the outer layer of paper closed at several points to hold snug. Once the plant is moved to its new pot and secure, then the wrappings can be carefully removed.

Remove the plant from its pot. Place it in the planting hole and press soil firmly around the roots, just covering the root ball. For spiny plants, use a stick, spatula, or other utensil to move the soil and to keep distance between your hands and the spines.

Repot every 2 years. Unless the roots are pot-bound the same container can be used. If a larger pot is needed choose one not more than 1-2” (3-5cm) larger in diameter than the existing pot.

Apply water at the soil level if possible to avoid wetting the plant. Water the entire soil area until water runs out the base of the pot. This indicates that the soil is thoroughly wet. Discard any excess water that has accumulated in the pot’s saucer.

Don’t water again until the top 1-2” (3-5cm) of soil is completely dry. Check the soil moisture with your finger. Plant may require less water during the winter months when it’s growing more slowly because of lower light levels. Some species may even go dormant for a few months in winter.

Cactus and succulent plants can be pruned to remove dead or damaged parts or to maintain a specific size or shape. Pruning encourages new growth, branching, and provides plant pieces that can be used for propagating more plants. Keeping the plant trimmed also encourages more side-shoots and reduces the demand for the plant to develop a larger root system. This is important since the roots are in a confined space.

Depending on the growth habit of the plant: long succulent leaves can be cut back to the base of the plant. Side stems can be cut back to the main trunk. If trimming to shape, cut off smaller segments just above a joint.

Baby cacti that grow on the main plant are known as “pups”. They can get very thick on some types of cacti. Pups can be cut off with a sharp knife at a 45-degree angle. Allow the cut area on the pups to air dry until a callous forms and they can be set in moist sand to root and eventually form new plants.

Some cacti and succulents produce “offsets”. These are plants that grow next to the mother plant by short rhizomes. These can be cut off at the rhizome and used to start new plants just like pups.

Fertilizers are available in many forms: granulated, slow-release, liquid feeds, organic or synthetic. Determine which application method is best for the situation and select a product with a nutritional balance designed for cactus and succulent plants.

Too much fertilizer can damage plants so it’s important to follow the package directions to determine how much, and how often, to feed plants.

Slow-release fertilizers are an especially good, care-free choice for container plants. A single application can often provide plants with the proper level of nutrition all season long.

A general-purpose fertilizer for house plants can be used for feeding cacti or succulents but it must be diluted to one quarter the strength of the normal rate.

Companion/Combination Plants

2 Comments

  1. Pamela Montgomery

    I have what I believe is an Old Man Cactus. It is a hand and a bit tall. Was going to plant another cactus with it, but notice the roots are spread throughout the pot. And close to the surface. It is doing fine but am wondering if it should be repotted. Some of the roots are exposed as it has been knocked over a few times. Dogs and cats.

    Reply
    • My Garden Life

      Hi Pamela,
      If you’ve had your old man cactus in the same pot for several years and it’s been steadily growing, there is a good chance it could use repotting, or at least a soil refresh. You’ll want to place it in a new pot that is 1-2” larger in diameter than the current pot – if the plant roots are truly are filling the current pot. Once you have your cactus out of its pot, you’ll be able to judge whether it can be returned to its current pot or needs an upgrade in size. If your intention is to plant two cacti in one pot, you will definitely want to go to a larger pot size.

      Use a soil mix designed for cacti and succulent and a pot with drainage holes. Clay pots are always a good choice for cacti as the terra cotta is porous and helps draw water away to reduce the chance of overwatering. Please see our article, How to Repot a Cactus, for tips on repotting.

      Reply

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