Q: I heard that you shouldn’t use wound sealer when pruning your trees – that it does more harm than good. Is this true?
Yes, it’s true. When pruning your trees, you should not use any sealer on the wound. Trees can heal from pruning cuts very nicely on their own. Sealing the cut can trap moisture, which will encourage fungus to grow. It can also trap disease-causing bacteria that can infect the whole tree.
When pruning a large branch, be sure to undercut a small distance closer to the trunk on the underside of the targeted branch. This will promote a clean cut and prevent the bark from being peeled away from the trunk when the branch falls. Always use clean, sharp tools when pruning – this makes your life easier and is better for the tree. Depending on what you want to accomplish, (size reduction, shaping, encouraging growth), there are several techniques for proper pruning. For more information, go to https://ucanr.edu/site/uc-marin-master-gardeners/pruning-cuts.
Q: Does Vitamin B1 really prevent transplant shock? I see it sold almost everywhere but have never tried it.
Vitamin B1 (thiamin) has been marketed as a cure-all for whatever’s ailing your plants, especially transplant shock. After extensive testing, researchers found no difference in plants grown with and without B1. I’ve noticed that some B1 supplements include trace minerals that are used by plants, so some people may have seen their plants benefit from being given it, but the plants’ improved health was likely due to the trace minerals, not the B1.
If you are concerned about transplant shock, especially when planting in late spring when the weather may warm up quickly and unexpectedly, there are several things you can do to help your plants out.
Check the weather forecast first. If there’s supposed to be a heatwave, or even a few unusually hot days, hold off on planting anything in the ground. If your plants are in small containers or six-packs, consider transplanting them into something a little roomier. This will buy you some time since the bigger containers won’t dry out as quickly. Relocate them to a shady spot under a tree or to a north- or east-facing side of the house, but don’t forget about them!
Many herb and vegetable plants are overcrowded in their containers. Look closely and you’ll notice there’s about 30 or 40 individual basil plants in a 3- or 4-inch pot. Ultimately, those plants are so overcrowded that they will not fare very well once they’re put into the ground. Sometimes you can tease the plants apart (I once got about 40 individual leeks from one 4-inch pot). Otherwise, you may want to cut back at least half of those little plants to give the others a fighting chance.
Los Angeles County
mglosangeleshelpline@ucdavis.edu; 626-586-1988; http://celosangeles.ucanr.edu/UC_Master_Gardener_Program/
Orange County
ucceocmghotline@ucanr.edu; http://mgorange.ucanr.edu/
Riverside County
anrmgriverside@ucanr.edu; 951-955-0170; https://ucanr.edu/sites/RiversideMG/
San Bernardino County
mgsanbern@ucanr.edu; 909-387-2182; http://mgsb.ucanr.edu