I have purchased some Pennsylvania Sedge (also known as Common Oak Sedge)...

Asked July 13, 2014, 11:56 AM EDT

I have purchased some Pennsylvania Sedge (also known as Common Oak Sedge) seed and would like to plant. The directions say to Fall plant or cold stratify for 2 to 4 weeks. What exactly does this mean? I have seen these plants at the Arboretum. What are your recommendations for planting?

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1 Response

Hello, To stratify seed means to artificially give the seed an environment which is required for the seed to break dormancy and start growing. In the case of your sedge, this is a cold period. According to my resources Carex pensylvanica, Pennsylvania sedge seed germinates at about 35-45% on average. That means about 35-40 seeds out of each 100 seeds should germinate when conditions are correct. This plant is considered difficult to grow from seed. Here is the USDA’s recommendation for germinating Pennsylvania sedge: “PROPAGATION METHODS: • Seed germination is moderate (34 – 45%). Stratify seeds by placing them in moist peat and store in cold (4 degrees C/39 degrees F) conditions for 90 days. Plant seeds in pots at 0.125 – 0.25 inches deep. Use peat based planting media. Keep in greenhouse until root system has filled the pot. RE-ESTABLISHMENT TECHNIQUES: Transplant seedlings in May or June when there is minimal danger of frost damage”. The lower section of your refrigerator should be cold enough. If you aren’t sure, get a refrigerator thermometer and set it in the section your will use. If you are going to raise the young plants in pots, you can sow the seed directly in moist potting medium, enclose them in plastic bags, and chill them, assuming you have the room in your refrigerator. Now you have two different recommendations for length of cold stratification – USDA says 90 days, and your seed supplier says 4 weeks. I would suggest you divide your seed and remove some of it at 4 weeks and try to germinate it. If that doesn’t work, then you will have your remaining seed left to chill at 90 days. Another university researcher found that by varying the day and night temperatures once the seed was sown in pots (after cold stratification of 8 weeks), a higher percentage of the seed would germinate. Day temperatures of 26 C (79 F) and night temperature of 18 C (64 F) had best success. This study planted the seed by pressing seed into pots without covering it. This is important- this carex requires light to germinate. I am not sure why the USDA indicated that it should be covered. So, as you can see, the research varies. In all cases you must keep the seed moist. You may want to try more than one method. Unfortunately, I could not find how many days it takes to germinate the seed once you remove it from the refrigerator. Since it is July, your best bet may be to sow some seed in the fall directly into the soil; and chill some seed starting next January or February, then grow that in pots. Starting the stratification now and planting out the result --- these plants may be too tender to establish well and survive the coming winter. Here is an overview of the plant --- – http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=f237 Good luck with your project, and thank you for using our service.