Valley gardeners often are frustrated when seemingly healthy warm-season produce (tomatoes, peppers, eggplants, melons, squash, cucumbers, etc.) fails to yield fruit. There are several factors why fruit fails to form.
Overfertilizing is a cause of poor production. Fruiting plants need a balance of nutrients to produce well. Too much fertilizer heavy in nitrogen causes leafy growth at the expense of fruit production. You want leaf-growth when growing cool-season vegetables, but warm-season vegetables suffer from excessive leafy growth. Besides chemical fertilizers, it’s also possible to overdo it with organics. It’s better to add fertilizer as needed, rather than starting out with too much.
Conversely, many gardeners are scared of overfertilizing and, as a result, underfertilize. This leads to smaller, yellowish leaves to produce food, poor fruit set, smaller fruit and eventually poor quality fruit. Keep an eye on the leaves.
Vegetables also suffer from adverse temperature conditions. Tomatoes, snap beans and just about all other fruiting vegetables, drop blooms when temperatures exceed 95 degrees. Blossom drop also intensifies in tomatoes when night temperatures remain above 75 degrees. Cherry tomatoes are the exception; they set fruit over a wider temperature range than large-fruited types.
High temperatures also adversely affect corn pollination. Once temperatures exceed 100 degrees, it kills pollen spewing from its tassel (male part of corn). Combine heat with dry winds, which blow pollen away, and you end up with cobs without kernels.
Blossom end rot is a fruit disorder caused by interruptions in watering. It commonly affects tomatoes, peppers, watermelons, cucumbers and squash, causing them to develop round leathery brown or black patches on the bottom of the fruit. Inside the fruit, tissue is hard and brown. The rot occurs when there is a lack of calcium supplied to developing fruit. We have more than enough calcium in our soil; blossom end rot develops by improper watering that disrupts the flow of calcium from the soil to the developing fruit. Therefore, keep the soil evenly moist.
I can’t stress the effects of high temperatures enough with tomatoes. Back in March, I heard cries that it was too early to plant tomatoes. Early plantings develop more fruiting sites before heat sets in. If they freeze, replace them. Moapa farmers plant in early February.
Pollination of vine crops also suffers from hot temperatures. Most commonly affected are bell peppers and squash. Bell peppers often develop misshapen and small fruit; fruit set does not occur when temperatures rise above 85 degrees, but hot peppers love the heat!
Vine crops also are affected by poor pollination. These plants produce male and female flowers on the same plant, with male flowers being dominant. Bees provide pollination for them. Hot weather reduces bee activity, and, in turn, fruit formation. If you can’t see a bee in your vegetables, you are not getting enough bee activity in your garden. And do not plant flowers around your garden; they distract bees from doing their job.
You can do the job of bees by hand pollinating your vine crops. Identify their female and male flowers. Female flowers of vine crops set atop an embryo, which resembles a baby fruit of the particular crop behind the flower. Male flowers do not have this attached embryo; they sit on pencil thin stems but have anthers covered with powdery yellow pollen.
To achieve pollination, remove male flowers from a vine and remove petals and simply rub the anthers against the stigma, at the center of the female flower. If you only partially pollinate the flowers, you end up with misshapen fruit. If you have children, this can be a very exciting project for them but do it early in the morning, for best results.
Water also plays a very crucial role in fruit production because water makes up most of the fruit in summer vegetables. Water stress causes blossom and fruit drop and you will get a lot of funny-shaped fruits. Be consistent through the life cycle of plants with watering. These vegetables love prolonged deep irrigations. Here is where copious amounts of organic matter you worked into the soil last spring kicks into gear. It absorbs water like a sponge, so roots extract it as needed.
Now the magic bullet: mulching. To best control these wide moisture swings from dry to wet, place organic mulch under veggies; it is the best remedy to control these wide moisture swings. Mulch also cools the environment around veggies.
Now for the other magic bullet: Organic matter becomes food for the many beneficial organisms in your soil. These “eager beavers” work feverishly turning it into humus and taking it deep into the soil. Looking down the road, it improves your soil for years to come.
Shading and the use of windbreaks are other moisture-conserving techniques. Plants that wilt in sunny areas benefit from shade during the afternoon. On windy days, air moving across plants removes moisture from leaves and roots cannot keep up with leaf demands. Temporary or permanent windbreaks can help tremendously.
Sunburning is another dilemma. Growing healthy plants with a good canopy of shading leaves is the best way to avoid burning fruit. Artificial shading also will help prevent sunburn. Locate a simple structure made with wood, covered by shade cloth to filter out afternoon sun.
Although we have no control over heat, it can cause these crops to become bitter, but you can reduce it by keeping up a good supply of moisture. And with all environmental problems related to heat and sun, it’s best to select and grow varieties proven reliable in extreme-heat conditions.
Many garden seed catalogs have a selection of vegetable varieties that will tolerate intense summer heat. Search for early ripening varieties, because they will mature before the heat sets in.
“Gardening for food” will be the first topic Don Fabbi and I will teach at 10:30 a.m. June 9 at the opening of the Las Vegas Springs Preserve, 333 S. Valley View Blvd.
The opening finally has arrived and I am like a kid on Christmas morning trying to figure out what presents to open first. You have to see the new gardens. They are a trip into the future as you wander through them. All the many new creations the Springs Preserve have dreamed up will keep your eyes wandering for hours.
Linn Mills writes a garden column each Thursday. You can reach him at email@example.com or at the Gardens at the Springs Preserve, 822-8325.LINN MILLSMORE COLUMNS