by Lee Squires

Soil and water are two of the most important components of bonsai growing success. Too much water or not enough are, most generally, the main reason for bonsai decline and eventual death.

Now, with this said, let's look into this subject and I'll make some suggestions that could make your watering simpler and possibly decrease your bonsai mortality. Success depends on the soil mix that is used.

Our club's basic mix, that we mixed in January, has three components: pine bark, lava rock and baked clay (SoilMaster Red). Unfortunately, none of these materials had been screened before mixing, so there is a lot of dust particles that will impede drainage in your containers. Screening at a club meeting is virtually impossible because of the time involved. None of us have all day to devote to a soil mixing meeting !

This is where tailoring your soil recipes for various species comes into play. Our club's basic mix is just that: a basic mix designed to be altered in different ways depending on what species you are potting. Our new members probably did not realize that this soil mix should be altered. Pines need ultimate drainage, junipers and other needle evergreens need superior drainage, deciduous trees need a soil that holds more water, azaleas need an acid soil with good drainage, etc., etc., etc. The list goes on and on, and I cannot in a brief article tell you what soil mix to use with each of your trees. Please purchase some good bonsai "how to" books to get you over the soil hurdle and apply some good basic horticultural knowledge to be a successful grower.

I'll generally start out with the basic mix and add various percentages of the three components, depending on what tree I am potting .I keep screened baked clay on hand, as well as pine bark and lava rock. Add more lava rock and baked clay to the mix for pines, and don't add any extra pine bark because of its decomposing qualities. Do the same with other needle evergreens, however with different percentage amendments depending on the needs of the species. Possibly use the basic mix with deciduous trees but, if there is too much dust for good drainage, you may have to add some lava rock.Add more pine bark or even some coarse peat moss for azaleas to provide the organic acidity that they need. This can be difficult, but experience and reading can give you plenty of knowledge to be successful.

Our speaker in February, Matt Ouwinga, uses straight, well-screened, baked clay in all of his pots, nothing else. This gives excellent drainage but requires extra watering during hot months, maybe twice a day. Who has time to water twice a day? Not me...

I'm sure you've heard of Akadama soil from Japan. Literally translated, it means" red clay balls". It is excavated from a quarry in Honshu, Japan, 75 miles from Tokyo. It is not fired or baked like our SoilMaster Red because, supposedly, firing increases water retention. It seems to me that firing would make it harder and cause it to release water faster. Guess not, according to the Japanese. Instead, Akadama is dried in hothouses to reduce water retention. It does not hold nutrients as well as the baked clay particles, so constant feeding is necessary using slow- release fertilizers. Akadama is the prime soil used on pines and other conifers in Japan and by "rich" American growers. Because of freight from Japan, it is expensive and probably too costly if you have a large collection of conifers.

Mainly, I'm relating this soil-tailoring issue to help you tremendously in your watering schedules. If all trees have the same soil mix, then you have to water all trees differently; less water on pines, more on azaleas and maples, water every other day on black pines, water Kihohime maples every day, skip the white pines on Wednesday, but be sure to water them on Friday, and if it rains forget watering altogether. This is a very confusing process and, for the beginner, can spell disaster with either too much or not enough water. I am a proponent of using a different mix with each tree that you have in your collection and tailoring that mix to the tree's water needs. If all trees have a different mix then you can water every tree every day and proper drainage will already be pre-set with no guesswork. If it rains, you may skip the pines for a day or two but hit the deciduous trees with a little water in between showers. This works perfectly and you don't have to remember when you previously watered the trees. This is perfect for when you go on vacation and you have your children or a neighbor water your trees. Just tell them to water every tree every day, plain and simple, and the soil mix will decide on how much water your tree needs. No dead trees when you get home !

If proper watering is an ART then proper soil mix is a SCIENCE. Your bonsai soil mix should not be taken with a grain of sand (no pun intended, just an over-used cliché).

In order for a soil mix to be a true soil, it must have clay in it. Our clay is the baked clay particles , SoilMaster Red. Mixes that contain pine bark, sand, gravel, lava rock, peat moss, compost ,etc. are classified as soil-less mixes by the nursery trade. A soil-less mix is a "short-term" mix and is meant to be in the pot with the plant for a short term, such as the mix used for annual or perennial flowers or poinsettias. The plants in this mix are fertilized with liquid, quick-release fertilizers and are, generally, foliar fed. Soil-less mixes do not hold onto the fertilizer, so it is useless to use a granular fertilizer with soil-less mixes. The plant is grown for a short period of time and then discarded or taken out of the pot and planted into the flower bed with "real" soil / clay. We all know that bonsai do best with granular fertilizers. Our bonsai trees are in the pot for the "long-term" therefore, "real" soil must be in the mix mainly, I think, to hold onto the fertilizer to make it available to the plant roots over the long term without leaching out through the drain holes when watering. I use a slow-release fertilizer like Osmocote ( 3 month release) so that fertilizer is available when the plant needs it.

If some of you in the club have been losing trees for some unexplained reason, this soil and water issue just may be the reason. Think about it.