Loblolly pine (Pinus taeda L.) somatic embryogenesis initiation was improved by supplementing the initiation medium with the pH buffer agent 2(n-morpholino)ethanesulphonic acid (MES) at 250 mg l−1, folic acid at 0.5 mg l 1, and biotin at 0.05 mg l−1. MES and vitamins increased the percentage of explants with extruded tissue that continued the initiation process to form embryogenic tissue. The increase in initiation was about 12%. Initiation of 12 open-pollinated families averaged 38.5%, which is 16% higher than initiation on medium without these additives. When tested with 18 control-pollinated families, initiation averaged 26.3%. Basal medium contained a combination of modified 1/2 P6 salts, activated carbon (AC) at 50 mg −1, Cu and Zn adjusted to compensate for adsorption by AC, 1.5% maltose, 2% myo-inositol, 500 mg l−1 casamino acids, 450 mg l−1 glutamine, 2 mg l−1 NAA, 0.63 mg l−1 BAP, 0.61 mg l−1 kinetin, 3.4 mg l−1 silver nitrate, 10 μM 8-Br-cGMP, 0.1 μM brassinolide, and 2 g l−1 Gelrite. Early-stage embryo growth and initiation in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) were also improved in the presence of these additives.