UNITED STATES—Neglected gardens demonstrate sustainability more effectively than maintained gardens. They display that which survives with minimal intervention. Also, that which requires too much intervention does not survive. Weeds are obviously too sustainable. They seem to survive anything. Desirable annuals are the opposite extreme, so do not survive for long.
Sustainable horticulture, excluding weeds, has become a fad. Unlike most fads, though, it is actually quite practical and sensible. In theory, it is horticulture that requires minimal intervention. It excludes what requires impractically intensive cultivation. Native species that grow wild, for example, are sustainable. Overly demanding tropical species are not.
A common problem with such fads is their marketability. They are too easy to exploit. Any commodity might be marketed as sustainable, whether or not it actually is. Sustainability sells. Realistically, in lucrative marketing, sustainability is unsustainable. It compromises any later needs for subsequent sales. Planned obsolescence is actually more lucrative.
Modern is not necessarily more sustainable.
Modern cultivars are not necessarily more sustainable than old cultivars. Simple species are generally more sustainable than their hybrids. Extensive breeding can cause genetic deficiencies. Variegation compromises vigor and can revert. For example, New Zealand flax is generally sustainable. However, some of its variegated cultivars commonly revert.
Again, native species are technically sustainable. They can survive without irrigation or intervention. However, in gardens that receive generous irrigation, some are susceptible to rot. Therefore, they are less sustainable for such situations. Also, some native species are not good options if combustibility is a concern. Sustainability involves many factors.
Many of the most common and passe plants happen to be the most sustainable. That is why they are common and passe. Lily of the Nile, African iris and many yuccas are some of the most sustainable perennials. Juniper, oleander and lemon bottlebrush are among the most sustainable woody shrubs. Realistically, there are far too many examples to list.
Highlight: Yellow African Iris
Common African iris is perhaps too common. That is likely because it is so resilient and easy to propagate. Once it inhabits the garden, it will likely stay there. Yellow African iris, Dietes bicolor, is about as tough and prolific, but it is considerably less common. Though similar to common African iris, it is distinct. It has a softer foliar texture and yellow bloom.
Bloom continues from spring through summer, as long as the weather is warm. The pale-yellow flowers are only about two to two and a half inches wide. They hover on slim but tough stems just above their foliage. Several flowers bloom in succession on each stem. Without deadheading, seed pods can disperse seed. Seedlings can become numerous.
Yellow African iris grows with foliar fans that form dense basal clumps. Collectively, they grow four feet tall and three feet wide. However, they can grow substantially broader with age. Large clumps are tough, but otherwise easy to divide. Foliage is somewhat grassy. Without grooming, it can become cluttered with old foliage and deteriorating floral stems. Overgrown clumps can be cut back after winter.
Tony Tomeo can be contacted at tonytomeo.com.
