When it’s time to plant out the first-year seedlings from our ongoing Dahlia Hybridization Project, we trench a 8” wide x 6” deep trough in our field for each row of babies. Then we take each 4” pot with its soil and 1 seedling, and plant the ENTIRE pot in the trough. We use the plastic pot to limit the growth of the seedlings’ roots so that we can keep the new tuber clumps separate. We grow thousands of seedlings each year, but won’t save the tubers from every one (although it’s hard not to! ) and we need to be able to grow intensively but keep the tubers from entangling. We learned this trick of planting in pots from hybridizer Paul Bloomquist, and have found it to be very helpful. I didn’t believe that it could work when I first heard about the idea, and was convinced the seedlings would be stunted with their roots so limited… but it works beautifully. Sometimes a very vigorous tuber will burst through the 4” pots, but still the limiting plastic is generally still containing the clumps, and the seedlings do grow gloriously to full height. And most of them are able to be reused even after working hard all summer! We tuck field dirt around the spaces between the pots in the trench, add two lines of drip irrigation, and mulch with wood chips or shavings to reduce water evaporation/suppress weeds. Then we enjoy discovering brand new hybrids and feed the pollinators all summer long. It’s truly a beautiful project!
Want to learn more about hybridizing and growing dahlias?
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