QUESTION: What kind of fertilizer can I use on my lettuce plants. I have some leftover tomato feed. Can I use tomato feed on lettuce? – Sam R
ANSWER: Tomato feed isn’t optimal for nourishing lettuce plants because blends for tomatoes are designed to especially promote fruiting. Tomato feed contains a higher percentage of potassium than nitrogen and phosphorus—and the extra potassium promotes flowering, encourages healthy fruiting, and has a hardening effect on plants.
The balanced fertilizers work better for lettuce than a tomato feed would because they’ll support the growth of lots of healthy, leafy foliage instead of trying to boost a fruiting process when it isn’t necessary. Lettuces need a balanced fertilizer (where the three numbers separated by hyphens are equal or close to equal), such as a 5-5-5 or a 10-10-10 blend. For best results, give lettuce plants a half dose of balanced water soluble or granular fertilizer every two weeks or so.
In addition to regular application of fertilizer, to grow the healthiest possible lettuce plants, you should also amend your soil before the lettuce seeds are sown. To prepare your ground for next season’s lettuce plants, work several inches of rich organic matter down into the top six to 12 inches of soil in your garden plot. (Aged compost, well rotted manure, fish emulsion, or another additive will set your soil up for success.) Ideally, you’ll amend soil in the fall before a spring planting so there’s time for the additive to decompose and release its nutrients into the soil. The waiting period also bypasses the risk of plants being damaged by the fertilizer burn that can come along with nitrogen-heavy additives like fresh manure or chicken manure.