Iron Supplements

An iron supplement is effective for both trees with yellowing growth, and for acid-loving trees such as Andromeda(pieris), Azalea, Camellia, Fir, Gardenia, Hawthorn, Hemlock, Holly, Juniper, Oak, Pine, Rhododendron, Spruce and many more.  If you have a bonsai that prefers acid soil, check out the pH meter below.  If you have a bonsai that has been yellowing, there's a good possibility that it's an iron deficiency.  In both cases, the following products may help.

M13 Mir-Acid Powder - 2 Sizes See Details Details
C9 Bonide Liquid Iron Concentrate - 32 Oz. $12.95 Details

ph1845 ph700 ph1847

Soil pH Meter

Whether you're growing a little $15.00 Juniper, or a $1,000.00 Chinese Elm, Your bonsai is affected by the condition of the soil it grows in.
A soil pH tester is a scientific tool for determining the capacity of your soil to provide nutrients and proper pH to a plant.
Virtually any bonsai would benefit from regular soil testing.  These pH meters are both accurate and affordable.
They feature an easy to read dial or digital readout and a soil probe.    Model pH700 needs no batteries.
Model pH1845 & pH1847 have the batteries included in the package. All three are very accurate instruments for the most serious bonsai hobbyists.
PH1847 Digital Soil pH Tester $ 15.99
PH700 Soil pH Tester $ 23.95
PH1845 Digital Soil pH Tester $ 23.95