Mary Blickenderfer, Shoreland Vegetation and Landscape Educator

You can spot us a mile away, scissors in our hands and pockets and packs bulging with bags of freshly collected native seed – the “bag people” of the native plant world! Once all the seed in those paper bags has dried on the porch or in the attic and/or the pulpy seed begins to ferment in plastic bags on your kitchen counter (see Minnesota Native Plants – Part 3 in July 2003 issue of this newsletter for collection instructions), you may be wondering “What do I do now?” The following instructions will help guide you through native seed cleaning and storage.

Cleaning seed

Dry seed: Remove seed from the seed head (shake heads in a bag, tap in a bowl, tease by hand, etc. – whatever works for the type of seed head you have). Sift with food strainers or a window screen (different mesh sizes can be used if available) and winnow (outside!) as necessary to remove the large chaff.

Wet seed: Clean when fruit is very ripe or fermenting. For stony seeded fruit, buzz briefly in a blender to separate the pulp from seed. If seed can be damaged by blender blades: wrap blades with duct tape, squeeze the fruit by hand while in the plastic bag, or work the fruit in a rigid container using a potato masher to separate the pulp from the seed. Rinse and decant liquid to remove the floating pulp and non-living seed from the viable seed that has settled to the bottom of the container. Repeat as necessary until decanted water is clean.

Storing seed

Dry seed: Place cleaned seed in labeled paper bags or envelopes. Store all labeled packages in a critter-proof container. A metal container with tight fitting lid is recommended. If insects are present, place pest strips in the container. Place container and contents in an unheated place (e.g., garage). Note: most dry seed, except seed of several sedge species, will retain viability for several years if kept dry, cool, and bug-free.

Wet seed and Wetland plant seed*: “Stratify” seed by planting it directly in flats containing moist growing medium. Place the entire flat in a plastic bag, label the bag, including the date stratification is initiated, and seal. Place in a location that will experience cold to freezing temperatures for a 6-8 week stratification period. A root cellar or unheated garage will work well for the flats, if critter-free. Check the flats during the stratification period: protect from critters and water, as necessary. If the seeds begin to sprout, remove them from plastic bags, place in a warm sunny location, and continue to care for the plants as necessary.

* Most dry seeds of wetland plants require a stratification to break dormancy (e.g., sedges, blueflag iris, boneset, Joe-pye-weed, swamp milkweed, blue vervain, etc.). Most other dry seeds will germinate more uniformly if stratified, but stratification is not required to break dormancy.

Other Notes:

As a general rule: store seeds under the conditions they would experience naturally if left unpicked. “Parachute-seeded” species (e.g., milkweed, asters, goldenrods, etc.) harvested just before they “fuzz out” are much easier to clean - if done immediately while the “fuzz” is still moist. A few species require “double stratification” (i.e. coldwarm- cold stratification). The first cold treatment is needed for root emergence. The second cold treatment is needed for leaf (cotyledon) emergence. Minnesota species that require this type of stratification include trilliums, highbush-cranberry, wood lily, and Turk’s cap lily.

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