Why do my tomatoes, peppers, or melons have dry rotten spots on the ends?

Blossom-end rot occurs on tomatoes, peppers, squash, eggplant, and watermelons from a lack of calcium in the developing fruits. It can be caused by fluctuations in soil moisture, rapid early-season growth followed by extended dry weather, excessive rain, excess soil salts caused by overfertilization (especially with high nitrogen fertilizers), and improper soil pH. Fungi or bacteria that invade the damaged tissue may cause moldy growths on the rotted area. The rotten area looks unsightly, but the rest of the fruit is edible. Applying preventive sprays of calcium chloride to tomatoes is not very effective. To prevent the problem in the future, maintain an even moisture level by regular watering and using good mulch. Plant in well-drained soil and avoid using high nitrogen fertilizers. Do not cultivate deeply close to the plant. Test soil and use lime as recommended to bring the pH up to 6.5 to 6.8. Smaller-fruited varieties, such as cherry tomatoes, are less susceptible to blossom-end rot.

Why won’t my tomatoes set fruit?

This may be due to extreme temperatures causing blossoms to drop without setting fruit. This occurs when nighttime temperatures fall below 55°F or stay above 70°F, or daytime temperatures rise above 90°F for extended periods. Recently, new “hot-set” varieties of tomatoes, such as Sun Leaper and Solar Set, have been developed that continue to set fruit at high temperatures. There could be other explanations.

• Does the plant get enough sun? Tomatoes need at least 6 hours of sunlight per day.
• If there is vigorous leafy growth but no fruit, there may be too much nitrogen in the soil, which stimulates leaf production at the expense of fruit formation.
• Drought also causes tomato plants to not set fruit, so make sure the tomato plant is getting 1 inch to 2 inches of water per week and is kept evenly moist.

Can my vegetables cross-pollinate each other?

Pollination is the transfer of pollen from the anther to the stigma (ovary) of a flower that results in seed and enlargement of the ovary producing a fruit. Cross-pollination is the transfer of pollen from a flower on one plant to a flower of another plant. Different varieties of the same vegetable can cross-pollinate (yellow and white corn) and some closely related species in the same family (squash and pumpkins), but not species in different families (corn and melons). Even if your pumpkin and squash or cantaloupe and Crenshaw did cross-pollinate, however, the fruit would still look the same. Only if the seeds from the fruit produced were saved and planted the next season would you possibly see differently colored or shaped fruit produced. There are some exceptions, such as planting hot and sweet peppers near each other. The gene for hotness is dominant, and insect cross-pollination can occur in peppers. Therefore, the seed produced in the current season’s sweet pepper may contain capsaicin, which causes heat, and your sweet pepper could taste hot. Corn kernels are seeds, and planting white and yellow corn near each other can result in cobs with mixed yellow and white kernels. Likewise, a supersweet corn planted near a traditional corn cultivar does not develop its sweet flavor.

Why is my broccoli, spinach, lettuce, or other cool-season crop flowering? Can I still eat it?

Cole crops or cold weather crops thrive in cooler temperatures. When the weather warms up in the spring, it can signal to cole crops that it is time to flower and reproduce. This rapid growth of flowering structures is often called bolting. While you can still eat plants that have bolted, they often contain a bitter sap that makes them unpalatable. Consider planting cole crops in the fall rather than the spring.

Why do my cucumbers taste bitter?

Cucumbers grown under environmental stress—such as a lack of water, uneven watering practices, high heat or cool conditions, wide temperature swings, low soil fertility, or low soil pH—produce increased levels of chemicals called cucurbitacins. These compounds are bitter and concentrated in the cucumber’s skin. Misshapen fruit from poor pollination can also be bitter. Bitterness also varies to some degree with the particular variety of cucumber grown. Overly mature or improperly stored cucumbers may also develop a mild bitterness.

How deep should I plant my tomatoes? They do not have many leaves on the lower stem, but they do have a few blossoms and one tiny tomato. 

Good early root establishment makes for the most prolific tomato plants. Tomato plants can produce adventitious roots all along their stem (see Figure 16-21), so burying the plant up to the first set of leaves can allow the plant to produce the most roots. If your plant is more than 6 to 7 inches tall, the soil below that depth could be too cool to promote the best root growth. In this case, consider digging a shallow trench and laying the tomato plant on its side (see Figure 16–22). Gently bend up the tip of the plant so it is above the soil line and cover the rest of the stem. Any blossoms or fruits should be pinched off because they can take energy away from developing roots.

Why are my broccoli or cauliflower heads small? And why is my cauliflower turning green?

When small heads form on broccoli or cauliflower, the condition is called “buttoning.” Excessive cold, nutrient deficiency, or drought stress (usually soon after planting) can cause buttoning. Large transplants are much more susceptible to buttoning, so look for plants with no more than four to six leaves. Cauliflower heads begin to turn green because they are starting to photosynthesize due to light exposure. When your head is approximately 3 inches across, you can keep light off of it by pulling leaves up and tying them together. This is known as “blanching.” Be sure to check on your plant frequently. If you notice it starting to bolt or elongate, harvest the entire head immediately.

There is a little tomato growing on my potato plant. Did they cross-pollinate?

Potatoes, tomatoes, eggplants, and peppers are in the Solanaceae or nightshade family. This family is self-pollinating, so unlikely to cross-pollinate. What you are seeing is the true fruit of a potato, which contains many tiny seeds. Do not eat the fruit, which is poisonous.

What is wrong with my zucchini plant? It has only produced a couple of fruits this summer. 

Zucchini are members of the cucurbits family, along with squash, melons, and cucumbers. Cucurbits produce separate male and female flowers. The male flowers produce large, sticky, yellow pollen that is not easily transferred by wind. The most effective pollinators for cucurbits are bees. Encourage native and honey bees in your yard by not spraying insecticides and by planting other nectar-producing plants. If you are in an urban area and have not seen many bees working your plants, try hand pollination. First distinguish male flowers from female flowers: Both have yellow petals, but female flowers have a tiny fruit at their base. Use an artist’s brush to collect some pollen from the stamen of a male plant, or remove the male flower, pull off the petals to expose the stamen, and place the pollen from the stamen or from your brush directly on the stigma of the female plant. It is best to try this technique early in the morning. It is important to use freshly opened flowers as they are only receptive for one day.