Summer is one of the best times of year for bonsai and can also be the worst!
Rapidly rising temperatures and hot dry winds can spell disaster if your bonsai are left un-attended for any length of time.
Watering to your trees needs, positioning your trees away from direct sunlight and sheltered from strong winds are probably the most important things to consider, and the hardest things to get right, especially if you are a 9 to 5 worker and not at home most of the day to attend to your trees should they dry out or get blown over.
WHEN TO WATER YOUR BONSAI:
When to water your bonsai is largely determined by your lifestyle!
If you don’t have a high tech automatic watering system or a full time gardener and you are someone who works all day you really only have 2 options.
Some books and nurseries advise watering every day, first thing in the morning.
The only problem I find with this is that throughout the day, your tree has to soak up water to replenish its usual needs, as well as replace the moisture being lost through its foliage, at the same time as water is being evaporated from the soil by the sun.
If this process becomes unbalanced and the soil is depleted of moisture too early in the day, your bonsai has no chance of replenishing moisture lost from its foliage and if this goes unchecked then it won’t receive more water till the following morning.
If you start work early, or like most people have more than enough to do each morning before rushing off to work, then watering in the afternoon or evening is your next best option.
Watering in the evening, or late afternoon is my preference but you still have to be careful as some varieties of bonsai are prone to fungus on branches and foliage if left damp for too long. Watering only the soil and avoiding the foliage from getting wet is a good way to avoid any major fungal issues.
Even if a tree has moist soil at this time, I will usually still water it as you have more chance of killing your bonsai from drying out then you do over watering it at this time of year.
Some other ways to keep your bonsai watered.
Another way you can keep water up to your bonsai is to place it in a shallow container with a few centimetres of water in the bottom. Varieties such as swamp cypress are more than happy in a dish of water and trees such as figs appreciate the humidity caused by the water evaporating from the tray of water below them.
Covering the soil in your bonsai pot with small stone, moss or other natural looking coverage can also act as mulch and also slow down the evaporation rate of moisture from the soil.
Keep a small area of soil uncovered so you can check to make sure the soil is not dry or too damp as some mosses will hold water or repel water while the soil below can be the opposite.
POSITIONING YOUR BONSAI
An obvious way to slow down how much water your bonsai needs is positioning it where it only gets early morning sun for a few hours each day, then is shaded during the hottest parts of the day. This minimises the amount of moisture evaporated from the soil and from the foliage.
PROTECTING YOUR BONSAI
Strong hot dry winds can not only rapidly dry out the foliage on your bonsai and burn tender new foliage, it can also blow trees off their stands breaking pots, or blowing trees clean out of their pots leaving exposed roots to dry out and cause irreversible damage.
Building screens or placing trees where they are protected from strong winds, taking trees off their stands if strong winds are forecast, and wiring your tree into its pot or to its stand, are a few things you can do to avoid wind being a problem.
Pests are extremely active at this time of year and can do a lot of damage in a small amount of time. Prevention is always better than cure. Do this by keeping your bonsai trimmed to minimise places that pests can hide, and regularly checking them over for signs of pest or disease is the best way to stay on top of them.
Remove pests by hand if you can or keep a can of white oil or pyrethrum on hand and this should work on most pests.
NOTE: Don’t spray on foliage in the middle of the day as this will burn the foliage. Most pests are more active at night, so this is a good time to hit them.