I dug a boxwood from an old residential lot before clearing at the end of February. I built a box and filled it with oil dry. The boxwood trunk is near 5" OD. It is watered every morning. The foliage has been reduced to about 70% and the remaining leaves look to be browning a bit. Should I build a plastic tent around the tree? Should I add something to the substrate? Is there anything I can do to keep this tree alive?
Tenting the tree can help with moisture retention, but I think you need to look further into your soil composition.
Here are some basic recommendations:
Basic mix: 50% Fafard 52 mix - 60% processed pine bark/40% combination of Canadian peat, perlite, and vermiculite 50% baked calcined clay - new brand: SoilMaster Red - this does not break down, adds porosity and air spaces to root environment, helps form dense root systems, aids in migration of water, fertilizer and oxygen throughout pot soil profile, and drains quickly. I always screen this through window screen to remove small dust particles which will clog soil.
This mix works well on deciduous trees and azaleas. To evergreens I add lava rock in various proportions.
Pines - 50% basic mix/50% lava rock
Junipers, false cypress - 75% basic mix/25% lava rock
For other trees: Research their soil needs and adjust the mix accordingly. I don't recommend a deciduous mix and an evergreen mix. There is too much variation on what plants need to restrict yourself to only two mixes. Also, experience tells you a lot about what to add. All trees will survive in the basic mix for a few years but you eventually have to modify it. For smaller trees you can try to use smaller particles in the basic mix. I do not sift for smaller trees. They all need good drainage with some larger particles.
Fafard #52 contains approximately 60% aged pine bark (a blend of fine and coarse), Canadian sphagnum peat, perlite and vermiculite. The mix also has dolomitic limestone (to adjust pH to 5.5-6.5), gypsum, a water-soluble nutrient charge, blue-chip (a slow release source of nitrogen) and a wetting agent.
Soilmaster® Red is a soil conditioner used to manage the moisture level of sports fields and to prevent compaction of the soil. I could not find the exact composition of this material except that it is an expanded clay.
When the lava rock was not available from the club, he used chicken grit (crushed granite) or kenlite baked shale. Lee does not screen the Fafard due to its dustiness. The SoilMaster Red is screened. Both the SoilMaster Red and Fafard are available locally from Bunton Seed Co.
Do not substitute "kitty litter" or Oil-Dri® for SoilMaster Red. Kitty litter sometimes has chemical additives and deodorants and may be the cause of some unexplained deaths of some trees in the past. These chemicals are extremely toxic to pines. Oil-Dri® turns to mush quickly when exposed to the repeated wetting and drying our bonsai ae exposed to. Also some Oil-Dri® contains chemicals used for oil adsorption. SoilMaster Red has NO additives and is meant to be used by the agronomy and horticulture professions. On the soil/pot surface sprinkle some baked clay. This hides the perlite and lava and gives everything a uniform appearance. Also, it will hold some moisture and help formation of moss.
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