Late Summer Fertility
by Joel Reiten

As summer’s peak arrives, the warm season crops like tomatoes and peppers shift into high gear, and the first green fruits get a blush of color as the days begin to grow shorter. Vegetables like tomatoes, peppers, winter squashes and corn have spent the last couple of months growing vegetatively, putting out lots of green leaves and vines to support the fall crop. As flowers appear and fruit is set, the plants are about to enter their reproductive phase and just like any good mother, they need to make sure they have plenty of nutrition.

If you’ve worked with composts or spring-tilled cover crops for more than a couple of years your soil is probably fine. You'll be able to tell by the dark green leaves and abundance of fruit set. However, you might want to look at adding some fertility if the leaf color is light green or a bit yellow, particularly on the newest leaves at the top of the plant or the end of the vine. Lack of available nitrogen is generally the culprit. The strong growth in early- and mid-summer may have taken most of the nitrogen from the soil and you will need to supplement.

Small amounts of relatively high nitrogen organic fertilizer either applied at the base of the plant or as a liquid sprayed over the plant’s foliage can help toward this end. Side dressing with a dry organic fertilizer, like Peace of Mind Tomato and Vegetable, or a liquid fish-based fertilizer like Organic Gem or Earth Juice Grow, will bring on a quick response. If my plants seem peaked with no yellowing I prefer the convenience of a liquid. I put it on with a hose end sprayer at half the recommended rate for two days in a row. I use the lower rate twice to make sure I don't cause any foliage burning in the bright sun. This is also a great way to apply to vining winter squashes as finding the base of the plant can sometimes be a challenge!

For tomatoes, peppers, eggplants and other ripening veggies that I can find the stems of, I like to use fast-acting guano-based fertilizers, like Earth Juice Grow or Bloom, as a soil drench, depending on whether I think more nitrogen is called for. (Grow contains abundant N for vegetative health while Bloom contains phosphorous and potassium that is more supportive of flowering and fruiting). This type of fertilizer is fast-acting and easy to apply. If you prefer a to use a dry fertilizer, be sure to work it into the soil well as organic fertilizers need to be broken down by soil microorganisms in order to be available to the plant. A good soaking also helps hurry the process along.

If mid-summer fertility in your garden seems to be a problem, now is a good time to start thinking about fall cover crops or maybe adding a layer of compost to the garden and letting it break down over the winter. This will help add the organic matter necessary for season-long nitrogen availability next summer and even greater yields from the garden.