Is Potting Soil Enough to Fertilize Tomatoes?

Garden Soil

• Tomatoes need deep, loose and acidic soil to thrive. Use potting soil as an amendment for garden tomatoes, but not as the sole growing foundation. Turn 1 inch of potting soil into the top 6 inches of garden soil, then add 2 inches of organic compost for nutrients and acidity. This foundation gives tomatoes good long-term support for growth.

Potting Soil

• Tomatoes in pots need richer, moister soil than garden tomatoes, as they dry more quickly in the restricted potting environment. The Ohio State University Extension recommends a potting mix of 1 part quick-draining potting soil, 1 part organic compost, 1 part perlite and 1 part sphagnum peat moss. This mixture provides better moisture and acidity than standard potting soil.

Fertilizer

• Start outdoor and potted tomato plants with granular 8-32-16 or 6-24-24 fertilizer, per manufacturer directions, to encourage rooting. While some potting soils contain fertilizer or food, others do not. Potting soil alone cannot satisfy the short- or long-term tomato-growing needs. Add more fertilizer when the first fruit appears on tomatoes. Use granular balanced 8-8-8 or 10-10-10 fertilizer for outdoor plants, per manufacturer directions, and reapply monthly thereafter. Use water-soluble 20-20-20 or 15-30-15 fertilizer on potted plants, and reapply weekly thereafter.

Water

• Tomatoes require more than soil and fertilizer to grow. Put them in spots with full sunshine and air movement, and keep them from going dry. Give outdoor tomatoes 2 inches of water every week, and potted tomatoes 2 inches of water every three to four days. Proper soil maintains moisture to support the tomatoes between waterings. Always water the plants immediately after a feeding to help disseminate granular fertilizer.