The following instructions have been provided by Darren Wong to insure our satsuki azaleas are repotted properly for health and vigor throughout the year:
• Start in February. Begin with the “narrow leaf” varieties ﬁrst. In March continue with all other varieties.
• Kanuma size is important; use 100% small size for shohin, for larger trees use a 50/50 mix of medium and small. The larger the azalea, the less small size you use.
• In general remove approximately 50% of root ball and 1″ from sides. Typically work down 3/4 to 1 inch on the surface. Sides should be ﬂat with slightly brushed edges so that a very, very small root end is exposed.
• Be extremely careful in combing out surface roots. If you use a rake turn it so the tines are parallel to the roots to prevent tearing. A better solution is a ﬁne root hook or chopstick.
• Use large drainage mesh on bottom of pot for everything except shohin. This helps water drain better in the pot.
• Use a layer of larger kanuma on bottom of pot for trees larger than shohin.
• Create a cone of soil in the center of the pot so that the tree can be ‘screwed’ into the soil to reduce air pockets under the tree.
• If repotting a bare-rooted tree, or one with open space on the bottom of the tree, be sure to all all holes with kanuma. Leave no air pockets which will result in dead roots = dead branches = dead trees.
Editor’s note: Jonas Dupuich just posted an excellent article on repotting satsuki where he recommends turning the tree upside down, ﬁlling all holes between roots with kanuma and working it in gently with a chopstick, then moistening the soil to keep it in place when the tree is turned upside down to go into the pot.
• After tying tree into the pot add kanuma slowly and work into the roots as you go, leaving no voids around the roots, but do not over work the chopping-in process which will crush the kanuma and impede proper drainage.
• Fill pot with kanuma once soil has been properly worked into the roots, and top off with a layer of mountain moss – yamagoke.
• After repotting products like Hormex® can be added to provide health to the trees and resupply beneﬁcial bacteria which may have been killed with a prior year treatment of Subdue®.
• Be mindful of watering after repotting and don’t overdo it.
• Keep trees protected from excess wind, cold and ‘Atmospheric Rivers’.
• Wait for at least 30 days to begin fertilization.
Second Editors Note: In a discussion with Peter Tea about the problem many have with root rot he suggested adding some pumice to the kanuma soil mix to create a drier mix which could reduce or eliminate the problem. Darren has not tried this and his take was to add about 20% yamagoke to the kanuma which might accomplish the same goal.
At our February meeting Bob Gould suggest that if the above method is tried with pumice that the drier mix should only be used on the bottom 1/4 or 1/3 of the pot.