Our Seed Collection and Germination Processes


The following information details the processes utilized by Twin Sisters Native Plants Nursery from seed collection to production of native plants.

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Seed Collection (spring, summer and fall)

Sustainable collection methods are used to ensure the continuance of source populations. Genetic diversity is attained by collecting representative samples of various populations of the same species. Seed collection is performed using mechanical seed stripers, vacuums or by hand. Collectors travel to locations near the target reclamation site. Large known populations of targeted species are monitored for seed ripeness.

Seed Cleaning and Processing (spring, summer and fall)

Depending on the species and seed type, seed will either be dried or cleaned immediately following collection to ensure maximum viability. This involves the removal of waste material from the seed itself, such as chaff or berry pulp. As appropriate, this process will involve the use of seed cleaning machines such as a Debearder (for grasses) or a Dybvig (for berries), sieves, hand separation, water baths and drying. Non- berry seed is kept in breathable material to avoid mould through rapid drying. Seed that does not require stratification will be stored until spring or alternatively sown fresh – as in the case of willow and poplar species.

Stratification (fall, winter and spring)

Many native plant species require some form of a natural stratification procedure over the fall, winter and spring months in order to break the seed coat and germinate. It is necessary to mimic these natural processes in the nursery setting in order to achieve consistent germination. 

Sowing (spring)

Once seed has germinated from stratification, it is sown into the styroblock trays to fill orders from clients. Some species which do not require stratification may be sown directly into the trays in the spring. The size of the tray will depend on specifications from the clients and the demands of the various species. The number of seeds sown in each cell of the tray will be determined by germination tests and experience.

Hardening Plants (fall)

Plants require a cooling off period before they are lifted for either panting or shipment to a cold storage facility. It is imperative to allow plants time to shut down their systems prior to either of these activities. This cooling off period will increase plant plug survival if planted in the fall and reduce the chance of mould if sent to cold storage. Cooling off is achieved by allowing plants access to the cooler temperature of fall without being exposed to sudden hard frosts. Plants are considered ready for lifting when buds are set and in the case of deciduous species, most of the leaves have dropped.

Lifting (fall)

Plugs may be lifted as “hot stock” in the growing season for “hot lift” planting (plugs are on the site immediately) or as “cold stock” for winter storage. Stock may be lifted late in the fall as a “semi hot lift” for fall planting. Plugs will only be lifted once they are considered ready. A key criteria for readiness includes a full firm root mass that does not fall apart when the plug is removed from the tray.When packed for cold storage the stock is placed in a plastic bag within a wax box and laid on its side in consistent bundles held together with cellophane wrap. When delivered to cold storage, plugs will be frozen and kept at a consistent temperature all winter, then thawed and planted in the spring once weather permits.