Growing and Care Of Rainbow Cactus

When looking for a hedgehog cactus with beautiful flowers, one of the first choices should be Echinocereus pectinatus (ek-in-oh-SER-ee-us pek-tin-AY-tus). 

The scientific name literally translates to “comb hedgehog”, a common name referring to the comb-like spines on its sides. 

blooming potted rainbow cactus synonym (echinocereus rigidissimus)
Echinocereus pectinatus synonym (echinocereus rigidissimus) – ziopoldaccio | Adobe

Some common names include: 

  • Rainbow cactus
  • Texas rainbow cactus
  • Ruby rainbow
  • Lace cactus
  • Purple candle cactus
  • Órgano-pequeño Peine

What makes this member of the Cactaceae family so special is the wide range of colors the spines may exhibit. 

The rainbow cactus spines are arrayed in a radial pattern with between 15 and 23 spines per areole, practically obscuring the red and white banded stem. 

When the cactus flowers, it adds even more color with large, bright blooms.

Native to Mexico and southwestern United States (primarily Arizona, New Mexico, and Texas), the plant is known to have one confirmed subspecies, Echinocereus pectinatus wenigeri, and one debated subspecies, which has been both classified as Echinocereus pectinatus ctenoides and Echinocereus dasyacanthus ctenoides. 

Echinocereus pectinatus var rigidissimus is the term commonly given to the plant when grown west of the Continental Divide and Echinocereus pseudopectinatus is another debated species to be a hybrid.

Adding even more confusion, comb hedgehog is also known by the alternate scientific names Cereus pectinatus, Echinocereus rigidissimus, and Echinocereus rigidissimus var rubispinus. 

Be sure to look for all of these names when shopping for a rainbow cactus plant or seeds.

Rainbow Cactus Care

Size & Growth

Being a hedgehog cactus, this species may have globose or cylindrical stems measuring between 8″ to 14” inches tall and 2″ to 5” inches thick. 

While the rainbow cactus plant is generally single, older plants may branch out to form a loose cluster.

The slow-growing plant features 20 to 23 obtuse ribs and essentially no central spines. 

Areoles are oval and close but not connected, with short white hair emerging from the younger ones. 

Meanwhile, 16 to 30 whitish to pinkish radial spines between 7/32″ and ⅜” inches long protrude from the areolae. 

They often interlink, forming bands of color and often getting flattened into a pectinate (comb-like) appearance.

The perennial rainbow cactus blooms occur throughout summer, starting as early as May and ending as late as August, depending upon the region. 

These give way to gooseberry-like fruits which are sweet and fully edible.

Echinocereus Rigidissimus Flowering and Fragrance

During the summer months, rainbow cacti produce almost comically oversized blooms. 

These flowers emerge from the sides of the stem as a spiny funnel shape and are diurnal. 

These flowers may be near-white, yellow, lavender, magenta, or an intense shade of pink and have cream-colored stamens.

The petals are long and pointed, while the whitish-green floral tube has white hairs. 

While not identical, the blooms resemble those of the Echinopsis genus. 

After three months, these develop into a greenish to dark purple-brown edible fruit with white pulp.

Light & Temperature

Succulents love sunlight, and rainbow cactus is no exception. 

Plant it in full sunlight to ensure optimal health. 

Indoors, provide a window seat near-full sun throughout the day.

Another feature of this plant is its ability to tolerate the cold for short periods of time. 

It may be grown from USDA hardiness zones 9a to 21b.

Watering and Feeding

It’s easy to overwater this cactus, so having a well-drained soil is an absolute must. 

Water once every two weeks during summer months, making sure the soil has dried out. 

Do not water if the soil is still moist. 

For winter, water only once a month, and avoid any watering at all when it’s humid.

As with many plants, it’s possible for echinocactus pectiniferus to become iron deficient. 

Give the plant regular feedings of diluted cactus fertilizer during the summer and supplement with sequestrated iron as needed.

Soil & Transplanting

Echinocereus pectinatus thrives on a standard cactus potting mix

Some evidence suggests it may be able to grow in slightly richer soil, although this is not generally advised. 

Avoid too much lime and aim for a neutral to slightly acidic soil with high grit content when planting outdoors.

Thanks to their slow growth, repotting is rare and may not need to be done for as long as two years at a time. 

To repot, carefully remove the cactus and knock away any loose soil. 

The roots tend to be weak, so be gentle with them. 

The plant may then be placed in the new pot and the roots covered with soil.

Grooming and Maintenance

Overall, the rainbow cactus requires very little maintenance. 

However, removing any plantlets and transplanting them is a good way to reduce its growth rate.

How To Propagate Comb Hedgehog

Older hedgehog cactus plants may be propagated through offsets. 

Remove the bud and allow a callus to form over the wound. 

Plant this in cactus soil and keep in a warm, slightly damp environment until it displays new growth.

For plants which may not have begun to bud, you may also propagate using seeds. 

The seeds germinate within two weeks when placed in a shallow mix and kept slightly damp. 

Transplant to pots as needed.

Rainbow Cactus Pest or Disease Problems

Unlike many members of the cactus family, comb hedgehog doesn’t have many natural enemies. 

It’s vulnerable to aphids, succulent mealybugs, and some moth larvae. 

A much bigger concern is rot, which is one of the most frequent killers of this plant when not in its natural environment. 

The plant is more susceptible to fire in natural settings.

Suggested Echinocereus pectinatus Uses

Echinocactus pectinatus is perfect for almost any ornamental use. 

It’s an attractive addition to rock gardens, desert-themed gardens, as a potted accent to porches, patios, and windows, or as a general indoor plant. 

Additionally, the fruits are edible, making this a great source for late summer snacking.

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