Duke Gardens strives to be water-conscious at every turn, from our recirculating water features to rainwater collection and plant care.
As water becomes an increasingly overused and ever-dwindling resource on a local and global scale, it is vital that substantial measures be taken to ensure its conservation. Here are some ways that Duke Gardens practices responsible water use.
The Duke Gardens rain cisterns are monstrous facilities for water storage. A 26,000-gallon cistern beneath the Terrace Gardens Fish Pool and another in the Discovery Garden store large amounts of rainwater, which is used to irrigate areas such as the Terraces and South Lawn. The concept of a cistern, which harnesses rain and diverts it for productive purposes, is hardly a new one—but it is nevertheless significant, as cisterns can help manage stormwater runoff and serve as a backup water supply in case of drought conditions.
In the Blomquist Garden of Native Plants, horticulturists have constructed a regenerative stormwater conveyance system (RSC) with gabions in the Carnivorous & Coastal Plain Plant Collection. The regenerative stormwater conveyance system slows and spreads stormwater runoff from nearby hard surfaces during storms, helping protect wildlife and sensitive habitats from erosion and damage. The RSC system is constructed with a series of small pools and gabions (the boxes of rocks) connected by boulders. The pools are deeper than they are wide, so during heavy rain, fast-moving water slows down as it flows over each section. Under each pool is a layer of sand and organic material that lets water soak into the ground. This helps reduce flooding, filters pollutants from the water and replenishes groundwater supplies.
Another way Duke Gardens minimizes water use is by incorporating mulch in soil beds. This helps lock in soil moisture because mulch acts as an effective water absorbent. Mulch not only reduces evaporation, but it also cuts down on weed growth, moderates soil temperature, prevents erosion and improves soil fertility. Leaves, pine needles, pine bark and wood chips compose most of the mulch used in the Gardens.
Drip irrigation, known to save water and fertilizer, supplies water directly to the soil or roots of a plant. Duke Gardens relies increasingly on drip irrigation, as well as on stream rotor heads that rotate and eject water in solid streams rather than misting. This reduces loss due to evaporation, proving to be 25% more efficient than conventional sprinkler heads. Drip irrigation functions well with mulch use because it doesn’t wash mulch away, unlike many other irrigation techniques.
Early morning hours (4 to 8 a.m.) are most optimal for watering. The Gardens’ automated irrigation system aims to operate between those hours in order to minimize water loss due to evaporation.
Duke Gardens’ curators are acutely aware of the water requirements of a plant before adding it to their collection, and drought-tolerant plants—agaves, yuccas, palms, cacti—are a plus. Plants endemic to the Southeastern U.S. are also smart choices because they are naturally tolerant of the fluctuations in soil moisture. We can harness their naturally built-in features to minimize water loss and maximize water uptake.
Questions?
Please contact us at gardens.duke.edu.