Gardening With Cold Hardy Succulents: Ocotillo, Rainbow Hedgehog Cactus, Chin Cactus
By David Salman
Fantastic Low Water Plants for Fabulous Flowers and Form
Many gardeners don't realize that there are cold hardy cacti and succulents--plants that can grow outdoors even in sub-zero winter climates. These types of plants, when grown in the ground, do best in areas of the Western US and western Great Plains that get no more than 18 to 20 inches of annual precipitation. If you want to enjoy them in higher rainfall regions, these waterwise plants need to be grown in some type of pot or container with a fast draining soil mix (see below).
New Succulents/Cacti for 2019
In addition to over a dozen returning-favorite varieties, High Country Gardens is excited to introduce a number of new cacti and succulents for spring 2019, including three rare specimens I’d like to highlight:
Ocatillo (Fouquieria splendens) is a keystone native shrub/small tree to both the warm winter Sonoran desert and the cold winter Chihuahuan desert. High Country Gardens is offering 5-year-old plants grown from seed collected in southern New Mexico (the cold, northern part of the Chihuahuan desert). Cold hardy to zone 7, this amazing species should be planted in the hottest, full-sun space in your landscape. The stems are very spiny and eventually reach over the roof of a one-story house. The brilliant scarlet flowers are an essential nectar source for hummingbirds and appear sporadically most any time of the growing season, depending when the rains materialize in winter, spring and summer. When conditions are extremely dry, the plant loses its leaves only to re-grow them after a couple of generous rains.
Rainbow Hedgehog Cactus
Rainbow Hedgehog Cactus (Echinocereus dasycanthus) is a barrel type that is usually unbranched and grows as a single stem that will often bend in interesting directions as it reaches mature height. The huge flowers are some of the most impressive in the genus Echinocereus and are usually yellow in color. But the species is variable with local populations in west Texas and southern New Mexico having pink, red and bicolor combinations. This species likes growing conditions that are hotter and drier than other cold hardy types. Rainbow Hedgehog Cactus shouldn’t be planted in areas that get more than 12-15 inches of annual precipitation if grown in the soil.
Minature Chin Cactus
Minature Chin Cactus (Gymnocalycium bruchii) is a very small growing species from the mountains of Argentina. The High Country Gardens offering is a selected form that is highly clustering, growing dozens of small grey stems. The flowers are large, relative to the size of the stems and are light pink in color. Plant it a cooler spot in the rock garden where it will receive afternoon shade. This plant will not be happy in hot sunny conditions.
Cold Hardy Cacti
Cacti are native to the Western hemisphere. There are cold hardy species from many locations in North American and the mountains of South America. Many species have especially showy flowers and are excellent companion plants for many smaller growing xeric native perennials and ornamental grasses.
Native Cold Hardy Succulents
Century Plants (Agave), Yucca and Ocatillo (Fouquieria) are some of most impressive cold hardy succulents. They range in size from small, almost miniature Agave to towering tree Yuccas that are the giants of the desert flora. The geometry of the foliage and the sculptural aspect of their shapes make them and fantastic addition to the xeric landscape.
Most yucca are not very sensitive to being grown in most types of soil (with the exception of heavy clay) and don't typically require the addition of sand and aggregate to their planting area.
Old World Succulents (from South Africa, Europe or Asia)
There are many outstanding South African succulents, commonly referred to as mesembs or living stones. Aloinopsis, Delosperma, Rabiea, Stomacium and Cotyledon are some of the best known genera and come from the cold, higher elevation deserts and mountain ranges of the Western Cape and Drakensberg region.
Even in arid climates of the US, they are most easily grown in rock gardens or as container plants. These fascinating succulents typically have huge roots that reach deep into the soil and are sensitive to wet soil over the winter months. In either use, rock garden or container, these plants put on a memorable flower show in early, mid- and late spring depending on the species used. In containers, their small size allows them to be grouped together in interesting combinations to provide a wide range of foliage types and flower colors.
Here are the key factors that will help you grow these cacti and succulents successfully in a low water (xeric) garden;
- Choose from the HCG cactus offerings as all of them are at least zone 7 cold hardy. Check individual species for their cold hardiness zone.
- Plant in the spring. Cacti need to be in active growth to grow new roots. Late spring and summer, when the weather is warmest, is their most active season of growth.
- Transplanting them bare root. Cacti and succulents do best when planted bare root. Remove the plant from its container, shake of the soil from the roots and spread them as you cover the roots. Be sure soil doesn’t go above the crown. We recommend watching our Planting Cactus video to learn how.
- Mulch with a crushed gravel to protect the plants from splashing soil (a significant problem in moister climates) and provide the roots with a more protected environment to become established. A mulch depth of 1 inch is recommended.
- Cacti and succulents require a fast draining soil in ground beds and containers. If your native soil is not sandy or rocky, then it will be necessary to improve the soil's drainage. A berm (low mound) or a wide 1 ft. deep bed can be created with a mix of 2 parts native soil to 1 part coarse sand and 1 part small gravel, porous red or black volcanic scoria (common in many western states) or expanded shale aggregate. This is the same recipe for filling frost resistant pots and containers in which to grow these moisture sensitive plants.
- Protecting them from excessive winter moister. In moister climates (more than 18 to 20 inches of annual precipitation), move the potted plants under the overhang of the roof on the south or west side of the house or outbuilding to keep the soil dry from rain and snow.