Outdoor Succulent Trial, Five-Year Recap
A summary or our 5-year outdoor succulent trail.
Our highly popular outdoor succulent trial program came to an end in 2021. Since its beginning in 2017, we evaluated approximately 462 different varieties of houseplant-type succulents and drought-tolerant foliage plants, across 60 different genera, for their outdoor performance. The goal of this program was to identify non-hardy succulents that have potential to be used in the same way as traditional annual bedding plants. I wanted to answer the question, “Instead of planting a marigold or a geranium, can I plant a jade plant or a snake plant?” And the answer in many cases was YES!
Our evaluation criteria for the succulent trial was slightly different than for our normal annual flower trials. For both trials, we were interested in things like:
1) Vigor, or how fast the plant grows and how substantial it is in the landscape
2) Wow-factor, or how eye-catching or unique.
In addition to these criteria, for the succulents, we also were interested in:
3) Resistance to sunburn, as these are plants that are typically grown indoors
4) Adaptability to our Michigan climate, including fluctuating temperatures and rainfall amounts.
Overall, we were pleasantly surprised at how well the succulents performed outdoors, but here are some of the most common issues we noticed:
1) Slow growth- I need a succulent that can “hold its own” when planted with other annuals. It cannot get swallowed up by its neighbors.
2) Permanent scarring from sunburn- the leafy nature of typical bedding plants allow them to “grow-out” of or cover up damage from sunburn (or chilling injury) that occurs soon after planting. Succulents, on the other hand, while they do grow and get bigger, the scarring tends to remain visible for much longer (and sometimes never gets covered up).
3) Rot from too much rain- most succulents are adapted to arid climates, so wet weather (especially prolonged periods of wet weather) can cause some varieties to rot and die.
4) Pests and diseases- succulents have their own set of common pests and diseases that sometimes, but not always, overlap with traditional bedding plants. In particular, succulents can be susceptible to aphids, mealybug, and powdery mildew. We even identified a very usual nematode that only affects Aloe, causing cankerous growth in the growing points. Luckily, this nematode seemed to remain isolated to a single variety, Aloe dorotheae ‘Sunset’.
Many of the varieties that performed well in our containerized trial, were later used in garden displays in the ground. For example, the bottom left photo shows a carpet-bedding style garden with Aloe vera and Senecio mandraliscae comprising the "M" and Sedum mexicanum 'Lemon Coral' as the background plant.
Here’s a quick list of varieties that performed particularly well in the trial (although there were many more):
- Aloe vera
- Echeveria ‘Purple Pearl’
- Echeveria ‘Topsy Turvy’
- Echeveria ‘Violet Queen’
- Graptoveria ‘Fred Ives’
- Kalanchoe marnieriana
- Oscularia deltoides
- Sansevieria (basically all species and cultivars we trialed)
- Sedum japonicum ‘Tokyo Sun’
- Sedum mexicanum ‘Lemon Coral’
- Senecio vitalis ‘Serpents’
- Tradescantia ‘Pink Panther’