Time to ?fertilize, sow second crop

It’s still early for tomato harvest in most North Coast gardens, but it isn’t too early for a second round of fertilizer. Savvy gardeners prepared soil weeks ago by digging in ample compost up to a foot deep before planting to get vegetable crops off to a good start. But as roots reached out beneath ground, they’ve already taken in a good deal of those nutrients. Now, they’re ready for more.

Tomatoes are considered heavy feeders, one of a group of crops that produce most abundantly when provided with additional nutrients as fruit development begins.

Good fertility in the root zone is critical for flowering and fruiting plants since most mineral compounds do not move freely through the soil. They need to be below the surface where plant roots can access them.

Certain nitrogen compounds are an exception. Some-mostly those applied in liquid inorganic form-move with water and reach roots easily, but the downside is that over-fertilizing simply allows this nutrient to leach away.

The advantage of organic fertilizers is that nitrogen is held in compounds that stay in place until soil microbes slowly break them down for take-up by root systems.

Spreading compost as mulch around plants helps hold moisture in the soil, but most of the nutrients don’t move very far underground. All it takes is a few probes with a trowel to work in the loose material followed by a thorough watering. Plants respond quickly, within a few days.

If you use granular or powdered fertilizers or liquid fish emulsion, they, too, are most effective in boosting production when worked into soil. Spread as a side dressing and cultivate 6 to 12 inches away from stems or in furrows between rows. Always follow directions on label when using packaged materials.

Other heavy feeders

Other warm-season crops whose developing fruits respond with gusto after a second round of fertilizing include peppers, eggplants, corn, onions, and all types of squash family plants-squash and pumpkins, cantaloupe and other melons, and cucumbers.

Note that potatoes aren’t as demanding as their tomato family relatives and are sustained by initial soil preparations without the need for a second application of fertilizer.

Anyone who has ever grown zucchini and other summer squash has learned that despite its appetite, withholding second helpings of nutrients reduces over-productivity, a legendary concern with zuchs.

Keep in mind when adding a second round of fertilizers that a little is good but excess may work against you by reducing the crop. Heavy doses of any fertilizer risk burning roots and damaging plants.

Too much nitrogen (the first number on a label such as (6-8-8) promotes foliage growth at the expense of fruit and will reduce if not eliminate a harvest.

Easy growers

All types of beans--bush or pole green beans, lima, soy, fava, and shell beans-are a gardeners dream for their easy care and modest demand for fertilizer.

Bean roots are shallow, reducing the need for deep cultivation, and their appetites are satisfied with an initial application of compost in beds before planting.

Beneficial bacteria live in nodules in a symbiotic relationship with bean roots and are able to transform nitrogen in the air (and soil) into usable forms beans can access, eliminating the need for supplemental feedings by the gardener.

Notable special varieties

It isn’t too late to plant more summer vegetables. I often wait to plant green beans, for example, until July 1, after all beets, cabbages, kohlrabis, and other cool-season crops are finished and cleaned out of beds.

Now that I’ve had success with a couple of lettuce varieties that promise success in summer heat, I’m continuing to sow seed, despite lettuce’s preference for growing in cool spring and fall weather.

ReneesGarden.com carries packs of leafy red and green, French and Dutch varieties labeled Blush Bavarians and Summer Bouquet, both of which are touted as heat tolerant.

Renee’s also features a compact bush tomato, round carrots, mini-butterhead lettuce, golden-stemmed hard, and Italian basil for miniature vegetable gardens as well as dozens of vegetables, herbs, and flowers suitable for container growing. My favorite of these is Astia zucchini, a compact grower that saves space in any garden.

Johnnyseeds.com, an excellent and information-packed website, is featuring a compact variety for fall gardens Minuet Napa cabbage. But there’s still time to plant several of Johnny’s small round or elongated eggplant that germinate in warm soil and mature in about 60 days.

Rosemary McCreary, a Sonoma County gardener, gardening teacher and author, writes the monthly Homegrown column for The Press Democrat. Write to her at P.O. Box 910, Santa Rosa, 95402.