June Bonsai Newsletter

DON’T LOOK NOW... Summer is here, hot and hotter. All of our tropicals are loving it, me, I am heading for the shade. Towards the end of this month and through July and August keep an eye out for heat stress, especially on certain trees that don’t like the heat.

We now go through the three hottest months of the year. We also will be starting the rainy season, hopefully. Don't let the rains fool you, it takes at least a 1/4 inch of steady rain to water your trees. I still water unless I receive a half inch. A rain gauge is a must. On days it does not rain your trees might need to be watered twice a day, once early morning and then watering the "soil only" in the heat of the day. Give your trees full sun from morning till around 2-3:00, then part shade. If they start heat stressing, move them to the shade earlier. Signs of heat stress: margin of leaves turning brown or curling, some leaves and/or leaflets dropping off or leaves appear somewhat dry or shriveled. Many species of trees will close or droop their leaves during the heat of the day, this slows transpiration, they should open, or raise back up when the temperature starts declining, if not, they are either not being watered sufficiently or they may need to be repotted. Generally the rains come in late afternoons which means the foliage stays wet all night, perfect conditions for mildew and fungus problems. A systemic fungicide applied now would be a good preventative on trees you know are prone to problems. We use Clearys 33G, which we have available.

FERTILIZING... Heavy rains can easily wash out all the nutrients in your fertilizer, even Osmocote can leach out a lot of its nutrients with too much rain. Tropicals are in their very active growing season so they will require more. Last month I gave all of my trees 8-9 month Southern Formula Osmocote. I use Peters 20-20-20 water soluble food once a month. Additionally, I use fish emulsion, mid-month, on trees I want to develop more, but not on my more finished trees. If I want flowers I use Bloom Buster. Ironite with 5% nitrogen is good for any tree that tends to yellow or get a little chlorotic, like your Bougainvillea or Philippine Jasmine. If your tree is not reacting to the fertilizer, has some yellowing of the leaves with darker veins, your soil is probably low on magnesium. This is pretty common with all the watering they receive now. Mix two tablespoons of Epsom salt in a gallon of water and water them as you normally would. Do not overfeed for this will increase the leaf size. This is only a basic fertilization program, you will need to tailor it to your trees.

INSECTS... With all the lush foliage on your trees every non-beneficial insect there is will be wanting to eat. Aphids, scale and thrips to name a few, can infest a tree in a matter of days. A systemic insecticide is good to use, because they only kill the bad bugs. Soapy water will take care of aphids, soft body scale, mealy bugs and other soft bodied insects. If you see ants on your tree you probably have aphids or scale. Spider mites are bad, especially on Junipers. By the time you notice the damage they have caused it is generally too late. Check for them by placing your tree on a white piece of paper and tapping the branch. Watch for movement on the paper, if you see any, you got them. You should check your trees daily for any signs of problems or just to say hello. Two days without water in this heat can easily kill a tree. A caterpillar can defoliate a tree for you in one day. If you notice the leaves on your Ficus benjamina varieties closed up and yellowing, you have thrips. We use Bonide and Merit, both a systemic insecticide which main ingredient is Imidacloprid, available here..

PRUNING... The trees you defoliated last month should have a flush of new growth on them. Keep all your biggest leaves cut off and your growth tips pinched back. If you are wanting a branch to increase in diameter do not pinch back, just let the branch grow until it is the size you want. Your secondary branches should be filling out now and you can be doing directional pruning on them to create more of your tertiary branches. By carefully selecting where to cut a branch, you can control the direction of new growth. On alternating leaves, clipping above a leaf on the right side of a branch will cause the new growth to grow to the right and vice-versa. If you clip above a leaf growing from the top of the branch, the new growth will go up. and likewise, clipping by a leaf growing on the bottom of a branch will cause new growth to grow down. With leaves that form opposite one another rather than alternating, clipping above these leaves will usually result in 2 new growths, one to the left and one to the right. You can choose either to be the new leader and the other to be a side branch or remove one to allow the other to grow in the direction you want. This will create the ramification and taper you want. If you wired last month keep an eye on them, tropicals grow fast and can wire scar before you know it.

POTTING... You can root prune any of your tropicals now except Black Olive, Buttonwood, Sea Grape or Texas Ebony, wait till later in the month or next month. Afterwards put them in shade for a couple of weeks or so until new growth starts, then slowly acclimate them back into full sun. The more sun you can give your trees, without heat stressing, will result in better ramification and smaller leaves.