Eremurus sp. growing in their native habitat. Courtesy of D. Lofti-Azad.
Success with a plant is inextricably linked to knowledge of that plant’s provenance. If you know what the conditions of plant in its native habitat are, you will have a good gauge of whether or not you have or can effectively create the right growing conditions for it in your own landscape. Beth Chatto is perhaps the pioneer of this approach, of using plants whose natural growing conditions match the growing conditions of your site. And on the surface this sounds like such old news and so completely obvious that why should we care? Because more often than not information on the specific provenance of a plant and the particular climactic, geological, and topographic conditions of that place of origin are not immediately available. Rather, we are given a generic set of guidelines by which to care for the plant: average water needs, keep evenly moist, plant in fertile soil, fertilize annually.
We take the various Eremurus / foxtail lily species as a case in point. Some entries may make vague reference to the plants being from places such as Iran, Afghanistan, and the Hindu Kush, but the buck generally stops here. Without any information on their native growing conditions, we are then offered up generic advice on care of these plants, particularly with regards to water. In the case of Eremurus bungei, this site says that the soil should never be allowed to dry out once they are planted. This one doesn’t mention water at all. And this says “Average Water Needs; Water regularly; do not overwater”. We are left with the impression that Eremurus bungei / foxtail lily must be from an environment that is neither too wet nor too dry and that is never affected by drought. And none could be further from the truth. Their native growing conditions are intensely dry, including in winter (which are somewhat cold), and rocky. The plants shoot out leaves during the brief time when moisture is available in the soil and must gather up enough energy as quickly as possible before the heat and drought of summer set in and they go dormant once again. In short they are the prototypical dry-landscape/high-desert bulb.
Allium growing in Iran. Courtesy of D. Lofti-Azad.
This is not common knowledge in part because nurseries are thinking about sales and would like to sell more Eremurus than fewer, and thus if they are advertised as needing average this and average that, then the average person in average anyplace USA can purchase and grow them, regardless of whether this is true or not (and, yes, it is somewhat true: you can prep your soil in various ways to make certain species of Eremurus grow in Minneapolis or North Dakota, albeit a bit tenuously). The other reason for the lack of information on native growing conditions of landscape plants is that species plants (as opposed to cultivars) are relatively new to the gardening scene. Heretofore the provenance of most plants was the nursery, end of story. And many plants have been in cultivation for so long that common knowledge of their origins has all but disappeared (did anyone know, for example, that geraniums are actually native to very dry regions in South Africa?).
We have nothing against cultivars at all and use them when need be, but our hope is that as interest in species plants grows, so too will access to detailed information on these species plants’ native growing conditions. The result can not only be increased knowledge of and interest in protecting the native habitats of these plants, but also in more sophisticated, climate-specific plant palettes that truly mesh with the ebbs and flows of the places they are located in.