The Great Unknowns

By Carl Elliott, SPP Conservation Nursery Manager

An SPP technician uses a hand lens to examine signs of insect damage on a plant grown in the nursery. Photo by Benj Drummond and Sara Joy Steele.

An SPP technician uses a hand lens to examine signs of insect damage on a plant grown in the nursery. Photo by Benj Drummond and Sara Joy Steele.

The cultivation of native plant material in a nursery is fraught with unknowns. Wild-collected and farm-raised seed often have erratic germination requirements and germination percentages from year to year. The year’s weather, seed collection times, and how seeds are cleaned and handled all can affect how the native plants grow.

Unknown conditions

Our wild seed collectors work carefully to reduce variables in timing, handling, and storage. They diligently follow protocols for every step in the process. But often variable summer weather plays a paramount role in defining seed quality, and that’s a factor no one can control. In 2013, spring rains gradually tapered off to bring a bright and warm July and August and provided a large crop of summer seeds; however, in early September rain made late-season seed collection difficult. We shall see in 2014 how the late summer ripeners, members of the Aster family (Solidago and Symphyotrichum species), germinate this spring.

Unknown water needs

Additionally, cultivating summer-dormant plants in containers poses establishment and survival challenges. A number of the plants we cultivate grow actively in the spring, but when the hot weather of summer arrives they go dormant. Leaves die back and small feeder roots slough off. The challenge is to keep the plants alive until planting time in the fall: too much water and the storage roots will rot; too little water and the plants dry up entirely. It is a careful balancing act until the plants wake up with September’s cool weather.

Offender Technicians examining nursery plants to identify insect pests. Photo by Jaal Mann.

Since 2009, SPP’s nurseries have built up a bank of knowledge and proficiency in prairie seed ecology and cultivation. To disseminate the knowledge, we hold seed ecology workshops at each nursery with the full crew of offender technicians. Graduate students present the workshops from a manual on the propagation protocols for each species cultivated. Our shared proficiency has yielded increased plug production at all three of our nurseries.

A workshop on the cultivation of harsh paintbrush (Castilleja hispida). Photo by Benj Drummond and Sarah Joy Steele.

A workshop on the cultivation of harsh paintbrush (Castilleja hispida). Photo by Benj Drummond and Sarah Joy Steele.

Unknown species

The same workshops also introduce plants for which we have no known protocol. The student describes the plant from seed, to active growth, flowering, and back to seed. The group investigates the ecological role for that plant on the prairies referring to primary research from the literature and field. Then, the technicians perform observations and measurements necessary to develop a draft protocol, and craft descriptions, weights and measures of the seed. Finally, SPP involves the technicians in scientific testing of the draft protocol. An example of a protocol under development is for a rare native plant of the Puget lowland prairies, Packera macounii.

Packera macounii. Photo by Keir Morse, Cal photos.

In the last five years, we have fully developed protocols for 37 native prairie species using this approach. In collaboration with our partners at the Center for Natural Lands and Joint Base Lewis-McChord, we are actively researching another 37 species to add to our diverse suite of plants for prairie restoration.

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