What fertilizer can I use for tomatoes and cucumbers?
Cucumbers and tomatoes will grow faster and taste better if you have enriched your soil with compost or good organic matter. Some of the expert growers maintain that adding dried seaweed to the soil to boost trace elements will give you stronger and better disease-resistant plants. Cucumbers need moderate nitrogen and high phosphorus and potassium, so an organic plant food with the first number lower than the last two (like 3-4-6) is good.
Tomatoes need soil that is high in all nutritional components, and that same organic fertilizer will work well. Fertilize your tomatoes just two times during the season--two weeks after planting and again just when the fruits are starting to set. Use an organic, low number fertilizer or a fish or seaweed emulsion. Adding organic matter into your soil in fall or early spring provides the most lasting benefit to your garden.
Don't forget a soil test for correct pH, and compost amendment.
Courtesy of NYBG Plant Information