Echinocereus rigidissimus

Echinocereus rigidissimus


Echinocereus rigidissimus subsp. rubispinus (Rainbow Hedgehog Cactus)

Echinocereus rigidissimus subsp. rubispinus (Rainbow Hedgehog Cactus) is a small columnar cactus with erect, cylindrical stems covered…

To determine if a plant is sufficiently cold hardy, the USDA created numbered zones indicating winter low temperatures the lower the zone number the colder the winter.

  • If the coldest winter temperature expected in your area is -15°F (zone 5) then any plants rated zones 3-5 will survive the winter temperatures in your area.
  • If you live in very warm winter areas (zones 9-11) plants with zones 3-4 ratings are not recommended. The lack of freezing winter temperatures do not provide a time for winter dormancy (rest).

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6-8” tall x 3-4” wide. Rainbow Hedgehog Cactus (Echinocereus rigidissimus) is a stunning Southwestern native barrel cactus renowned for its huge magenta and yellow, early summer flowers and the tight growing pink and white spines. It demands fast draining sandy or rocky soil and a hot, sunny spot in the garden. For gardeners that live in moister areas outside of the Southwestern US, it's better grown as a container plant, planted in glazed, hard-fired pots. Good companion plants include Fame Flowers (Phemeranthus), other cold hardy cacti, and smaller growing Penstemon.

Tips for Growing Cacti and Succulents

Cacti shipped early in the spring may be dormant. As the weather warms, these cacti will expand and green-up. Remember, after an initial watering to settle the soil around the roots, no further water should be applied until the weather warms up. If plants are dormant and the spring weather is rainy, protect the plants from too much moisture by covering them with a gallon plastic milk container with the bottom cut out. Leave the top off the jug so heat build up isn’t excessive in sunny weather.

Soil Preparation

All the species of hardy cacti and succulents require fast-draining soil.

Planting in the ground

Put the plants on a slope or raised area of the garden, not in a low spot which collects water. Select a bed with full sun exposure, preferably next to a south or west facing wall. These areas will provide extra winter warmth. In heavy clay soils, it is essential to replace half or more of the soil from a 10”x 10” or larger hole with coarse sand and gravel mixed thoroughly with the remaining soil to ensure adequate drainage. No compost should be added, only a small handful of Planters II and Yum Yum Mix®.

Planting in an outdoor pot or planter

Use a planting mix of 3 parts garden soil + 2 parts coarse sand + 2 parts coarse perlite (or similar material). When growing plants indoors in pots, use a good quality potting soil to mix with the sand, and expanded shale instead of garden soil.

Planting Instructions

1. Cacti, agaves, and tap-rooted succulents (Aloinopsis, Titanopsis, Nananthus) should be transplanted bare-root. Let the soil in the pot dry out for a few days. Then remove the pot and gently loosen the soil so it falls away from the roots. Trim off any broken roots. Bare root plants should then be planted into a shallow hole. Spread out the roots evenly and sprinkle the soil into the hole until full. The base of the plant should rest on top of the soil. Mulch with a 1⁄2”-1” thick layer of pea-sized gravel around the base of the plant to protect it from contact with soggy soil over the winter months. (See planting diagram on page 12 of our Planting Guide.)

2. Succulents with fibrous roots (Ruschia, Delosperma, Sedum, and others) need not be transplanted bare-root, instead, the root ball should be scored and roughed out like other perennials.

1. Bare-root cacti and tap-rooted succulents must not be watered right away, but should sit dry for a day or two to allow the roots to callus over any broken or damaged areas. Other succulents can be watered in right away. Water thoroughly with a mixture of SeaCom-PGR and Superthrive to stimulate strong new root growth. Water again with this mixture two weeks later.

2. Outdoor beds with new plants should be initially watered once every 5 to 7 days for the first month or so after transplanting. Cacti and succulents enjoy regular watering during the heat of the summer and will grow vigorously. After the first year, most cacti species need a good soaking only once every 2-4 weeks during the spring and summer if there has been no rain.

3. Potted plants require more frequent, regular watering, especially if the weather is hot and dry.

4. To prepare cacti and succulents for the approach of winter, begin withholding water in the fall so the plants can begin to dehydrate and shrivel. Plump, well watered plants are ripe for cold damage when temperatures plunge in late fall/early winter.


Cacti and succulents are very modest in their fertilizer requirements. When planted in the ground, fertilizing in spring with SeaCom-PGR and Yum Yum Mix® will encourage plentiful flowers and good stem growth. When planted in pots, remember to feed monthly with the same mixture as above, beginning in late summer.

Winter Protection

Garden plants: Many cacti and succulents are quite cold hardy if kept dry in the cold winter and spring months. In areas that receive a lot of winter and spring moisture (especially rain), it is strongly recommended that plants be protected from cold, wet soil conditions. For example, a temporary cold frame can be constructed using pipe or PVC hoops covered with a clear plastic sheet to cover the entire bed. Or individual plants can be covered with plastic gallon milk jugs with the bottom cut out to keep the ground around the plants dry. Leave the top off the jug so heat build up isn’t excessive in sunny weather. Problems will occur if plants are in wet soil all winter or sit under melting snow for extended periods.

Potted plants: Should be moved under a roof overhang on the south or west side of the house or placed in a well ventilated cold frame. Water pots and other containers lightly a few times over the winter during warm spells.

All our cacti, agaves and succulents are seed-grown or cutting-grown in our greenhouses. Cacti and agave plants are 2-4 years old succulents are 1-2 years old. Please, never collect cacti from the wild unless it’s to rescue plants from construction sites. Many species are close to extinction in their native habitats due to irresponsible collectors.

ZoneShipping Status
Zone 2Shipping begins the week of May 17th, 2021
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Zone 5Shipping begins the week of May 3rd, 2021
Zone 6Shipping begins the week of April 19th, 2021
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Zone 9Shipping begins the week of April 5th, 2021
Zone 10Shipping begins the week of April 5th, 2021

As soon as your order is placed you will receive a confirmation email. You will receive a second email the day your order ships telling you how it has been sent. Some perennials are shipped as potted plants, some as perennial roots packed in peat. The ‘Plant Information’ section describes how that item will ship. All perennials and spring-planted bulbs are packaged to withstand shipping and are fully-guaranteed. Please open upon receipt and follow the instructions included.

Perennials and spring-planted bulbs are shipped at the proper planting time for your hardiness zone. Perennial and spring-planted bulb orders will arrive separately from seeds. If your order requires more than one shipment and all items are shipping to the same address, there is no additional shipping charge. See our shipping information page for approximate ship dates and more detailed information. If you have any questions, please call Customer Service toll-free at (800) 925-9387 or contact us by email.

Echinocereus rigidissimus (likely var. rubrispinus)

Published by Daniel Mosquin on December 8, 2006

A thank you to billy [email protected] (starter of the Flickr “Fat Plants” group) for sharing today’s photograph (BPotD Flickr Group Pool | original image). Much appreciated!

The simplest name to apply to this plant is the common one: rainbow hedgehog cactus. I made an attempt to figure out the most recent accepted scientific name and had to abandon it. “billy liar” stated this plant’s name was Echinocereus rigidissimus var. rubrispinus (the varietal epithet meaning red-spined), but when checking the nomenclature, I ran into a few problems. The USDA Plants Database entry on Echinocereus rigidissimus doesn’t subdivide the species into subspecies or varieties. However, the distribution of this taxon extends from southwest USA into Mexico, so it is quite possible that the variety rubrispinus only occurs in Mexico, and so wouldn’t be covered in the USDA database.

This does seem to be the case after browsing through Echinocereus Online where it lists the taxon Echinocereus pectinatus var. rubispinus as occurring in Chihuahua, Mexico. This reference suggests that Echinocereus rigidissimus var. rubrispinus is an outdated name. However, looking back at the USDA database, it seems those taxonomists would make the opposite conclusion, based on their listing of Echinocereus pectinatus var. rigidissimus as a synonym for Echinocereus rigidissimus. Conclusion? Confused.

How to Grow an Arizona Rainbow Cactus From Seeds

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The Arizona rainbow cactus (also known as the rainbow hedgehog cactus or Echinocereus rigidissimus) thrives in U.S. Department of Agriculture zones 6 through 10, where it reaches heights of about one foot. It can take up to a year before you have an established cactus to show for your work, but the process pays off in spades: This succulent plant sprouts spectacularly showy, funnel-like flowers in bright hues of red, pink, purple, yellow or white.

Fill a small, clean plant container -- preferably a shallow container, about 4 inches deep, with drainage holes -- with pasteurized potting mix. Mix in granite, perlite or pumice to a ratio of half potting mix and half soil additive. Amending the soil with one of these additives helps encourage proper drainage. Water the soil through and allow it to drain.

Spread a layer of Arizona rainbow cactus seeds on the topsoil. Cover the seeds lightly with your amended potting mix. Place a transparent lid over the top of the container. It doesn't have to be a perfect fit, as long as it covers the lip of the pot. This helps your cactus retain moisture during the germination process.

Choose a sunny indoor location for your Arizona rainbow cactus. This plant enjoys plenty of light and warmth, but for best results, move the container away from direct sunlight during intensely sunny parts of the day, such as high noon.

Keep an eye on your cactus as it germinates. With mild sunlight, the initial soil moisture and the condensation collected on the lid may be enough to water the seed during germination. If you don't see signs of condensation on the lid, test the soil with your finger -- your cactus needs moist soil throughout the germination process. When spines appear, remove the cover to allow ventilation. Typically, germination takes about two weeks. Until you transport the plant, keep the soil moist, never completely dry but never waterlogged.

Transport your rainbow cactus to a larger container, about twice the size of the first one, six months to a year after planting. By this time, the plant should be about the size of a grape. Allow the soil to drain completely before transplanting. Using the same soil mix as before, gently lift the entire plant and move it to the new soil-filled pot. Pat the soil around the plant until it feels firm. Water your cactus slowly and deeply immediately after transporting.

Place the young Arizona rainbow cactus in a shady outdoor location that receives plentiful air flow. Ideally, the move outdoors is done during cool, mild weather. Keep the plant in a shady location or one with dappled sunlight until it grows to about 3 inches across. At that point, you can move it to a spot that gets full sunlight exposure.

Watch the video: Cacti Identification Ep 01