By October, the Japanese maples in our central San Joaquin Valley gardens are looking a little burned-out and shaggy. Although some Japanese maples (the palmatum types more than the lace leaf types) can tolerate higher temperatures and sunnier locations, most Japanese maples do best with temperatures below 90 degrees and morning-only sun. Maples planted with southern exposure that receive 14 hours of summer sun will now be losing crispy brown leaves instead of putting on a magnificent show of fall color.
Antitranspirant sprays that reduce moisture loss from plant leaves are available at most nurseries and garden centers. Keep them in mind for application next summer if the leaves on your maples are scorched.
Japanese maples have four growth spurts or “pulses” during the season and the last one is in fall when long whip branches suddenly appear, deforming the natural shape of the tree. Those whips should be cut all the way back to the trunk. The tree may also be setting clusters of small leaf stems along the trunk and main branches. The clusters can be rubbed off with your gloved fingers when tiny or trimmed off with pruners if they’ve hardened.
Pruning Japanese maples is a real art and the effects of poor pruning will be clearly apparent now during the fall growth spurt:
▪ Branches that were chopped off across the tips will have weird leafy clumps at the site of the cuts.
▪ Bark will be sunburned and cracking if too much growth has been removed.
Remove the whip branches and the small leaf clusters and then take a trip to the Shinzen gardens in Woodward Park in Fresno to get a good sense of how a well-pruned Japanese maple planted in the right conditions should look in fall. The designers of the Shinzen garden have done a masterful job of creating shady, cooler microclimates that protect the maples from our harsh climate.
If you’re considering buying a Japanese maple, think about keeping it in a pot. Pots restrict root growth which helps maintain a manageable size-just like bonsai plants. Plan on removing the tree from the pot every two to three years to shave the roots down before they completely fill the pot. Japanese maples do quite well in pots – I have had three healthy specimens in pots for over 15 years. The trees have maintained a modest size, several feet high. They’re set on saucers with wheels so that they can be moved into full shade as needed in summer then set outside my home office windows in fall and spring so that I can enjoy them every day.
Send Elinor Teague plant questions at firstname.lastname@example.org.