General watering tips. By Mark Paterson
1. Check your tree(s) every day.
2. Lift the pot frequently. Learn the difference in weight between the well watered pot and a dried out pot.
3. Use a bamboo cooking skewer as a hydration meter. Leave the skewer in the soil. Check the skewer daily by pulling it out of the soil. If the stick is damp, the moisture level is fine. If the stick is dry, it’s time to water.
4. In spring the tree starts taking up water before it shows signs of new growth. If the seasonal rains have tapered off, trees may need increased monitoring, and will require even more water when the leaves emerge.
5. Don’t water within four hours of expected below zero tempuratures. Give the pot time to drain the excess water which would otherwise expand when freezing, and cause damage to the roots and/or pot.
Specific watering tips.
Bonsai tree in garden or potting soil
In summer, water the tree every day. If the plant ever feels really light, even after watering, treat it for a day as though it were in old compact dirt (below). In winter, on Vancouver Island, your tree will get enough water from rain (provided it’s not partially sheltered). Some species may find Vancouver Island’s rainfall excessive.
Bonsai tree in old, compact garden or potting soil.
Water the tree as above. However, when watering, water twice. Most of the water will probably run off the first time, down the insides of the pot. More of the water will be absorbed in the second watering. The more compact the soil the more one should repeat the watering. It also helps to break up the surface of the soil with a chop stick, or other tool, so that water can more easily penetrate. Most potting soils contain fairly large amounts of peat moss. When moist, peat moss can keep soil mixes too wet and often encourage rot. When dried out, peat moss is capable of repelling water quite effectively, preventing the soil mix from picking up adequate water.
Another technique is to place the bonsai in water so that the entire soil mass is underwater. The water will displace the air from the the soil, thereby soaking the planting medium. You may leave the plant submerged for up to half a day. Any bonsai, in any soil, may be watered this way it’s just somewhat labourious.
Bonsai tree in bonsai media which is partially soil.
This includes catus soil. Treat as “soil” or “compact soil” according to the density of the mixture. The more recent the potting up, the more rapidly the mixture is likely to dry out.
Bonsai tree in inorganic bonsai media.
Products such as Akadama and kanuma, or our own regional mix of granite, pumice, turface and lava (with some portion of organics) are free-draining and promotes growth with superior root airation qualities. These mixes dry out quickly, often within hours. Do not go away overnight without some form of automatic irrigation.