Polyculture Maintenance and Plant Palettes
This post is about the maintenance decisions that can have a profound effect on the range of plants useful for an aesthetically qualified urban polyculture. Some of the issues are addressed in the spreadsheet that was presented in part 8 of this series. For example, relative aggressiveness will help determine if plants play well together or if one plant is almost sure to dominate. However, the discussion that follows is on factors affecting plant palette decisions that go beyond the intrinsic characteristics of each plant that is considered.
Polycultures of herbaceous perennial plants and grasses are low maintenance but will frequently be more useful for aesthetically qualified native urban polycultures if they are pruned two or three times a year. Just because a plant is native does not mean that it must be allowed to express only its non-maintained form. This is especially true when soil amendments and irrigation are used. Water, fertilizer, and soils that are richer than what the plant would normally grow in without human intervention tend to make the plants taller, fuller, and more aggressive than otherwise, and may even cause them to flop over, particularly when they are blooming. Selective pruning may actually bring their appearance and stature back closer to a “natural” state.
Another big advantage to selective pruning is that it broadens the range of plants that can fit the aesthetic criteria of a particular polyculture. For example, one of the best native plants we have for shade conditions in North Texas is Inland Sea Oats (Chasmanthium latifolium). It is tolerant of both drought and seasonal inundation, stays attractive throughout the year, and establishes and spreads very easily. However, with irrigation it can easily get 3-4 feet tall, which may not be a desirable trait in an urban polyculture where other lower plants could have a seasonal focus. By cutting Sea Oats in half early in the season, it can easily be maintained at 18 inches tall. Some of the plants can also be left taller as “scatter plants,” which is how we are maintaining the UT-Arlington polyculture featured in part 7 of this series.