QUESTION: What is the best fertilizer for spinach? Should I use liquid or granular? -Ted L.
ANSWER: One option is to amend soil prior to planting. Try working in a combination of compost and a balanced fertilizer into your soil. Time the soil amendment just a few days before planting. This timeline allows the fertilizer has a chance to break down some.
Once your spinach plants are established, you can use a balanced fertilizer. A fertilizer with a bit more nitrogen might work even better. Something like 10-10-10 is successful, but a 15-10-10 is preferred.
Before planting, use a granular fertilizer. Then switch to a water-soluble fertilizer once the plants are established. We suggest switching to water-soluble because it is easier to feed the spinach plants without disrupting their shallow root systems. Fertilize every two to three weeks or so during the growing season water-soluble fertilizer.
If you prefer to use a granular fertilizer during the growing season, use it as a side dressing along the edge of the rows and apply it once per month. Be sure not to let the granules come in direct contact with the plants. It can burn them. Water in the granular fertilizer immediately after applying.
You may be interested in using organic fertilizer. Use fish emulsion or well-rotted manure to amend the soil before planting. Side dress with any organic fertilizer that is rich in nitrogen during the growing season. Composts also work well for organic feeding and can be applied once or twice per growing season. Any water soluble balanced or nitrogen-rich organic fertilizer will work just fine.