Cucumbers

This usually happens when you seed in dirt instead of sterile or pasteurized potting soil. It's known as "damping-off." Use the proper medium and be careful not to overwater. Give them lots of light and make sure they're not too crowded so they get air circulating. Good luck!

Avoid watering the leaves

It's hard to say why the leaves turned yellow. Read the planting advice above and make sure that you keep the soil around the plants moist.

The recommended size for cucumbers is:
20" wide, 16" deep with soil volume of 4-5 gallons per plant. Cucumbers have deep root systems and aren't the best choice for shallow boxes. Here are some varieties that do well in containers: Sweet Success, Suyo, Salad Bush, Bush Slicer, Burpless, Liberty, Early Pik, Salty and Crispy.

Build a frame and have a sheet of tin at the bottom. Then fill it with whatever soil you are using.

To avoid bitterness, provide 1 to 1 1/2 inches of water in a single application, especially during dry/drought periods. Apply mulch to retain moisture. Plant cultivars that are listed as being bitter-free in the garden catalogs. Examples: Carmen, County Fair, Diva, Green Knight, Sweet Slice, Sweet Success and Tasty Green.

Look for varieties that have "pickling" in the name. Most mail order sources have a section for pickling cucumbers. Pick the cucumbers when small, don't let them grow longer than 4-5 inches.

This sounds like a pollination problem. Next time, try growing plants that attract bees along with your cucumbers. Or you can try to pollinate the cucumbers yourself.

Water cucumbers deeply, applying 1 to 2 inches per week unless weather is especially dry. Cucumbers need good drainage and shouldn't be watered from above. Carefully water at soil level with a hose so as to not get any water splashing on the foliage.

No, do not eat the yellow cucumbers. They are over-ripe and should be discarded or added to your compost pile.

Sometimes it depends on the variety. Cucumber skins can be smooth and thin, or thick and rough.

Misshapen fruit usually happens from incomplete pollination. The bees need to return and again and again. Sometimes, the later fruits will be a proper shape. In terms of the "shriveled" issue: If the female flowers bloom before there are male flowers to supply pollen, they will dry up or produce small fruits that drop off and die. Again, this is often corrected later in the season once the both flowers are blooming and there is plenty of pollination. Lack of pollination can be related to lack of pollinators (i.e., bees) or some rainy, interruptive weather. You can always hand pollinate.

If your cukes are yellow—and they are not supposed to be (they are not a yellow variety, such as "lemon cucumbers"), they are probably overripe: the chlorophyll that makes them green has begun to fade. The color may also signal a virus or that they had too much water. Examine the plant for other signs of disease and/or consider your recent watering habit and the weather. Yellow cukes may look fine, but they are likely to be bitter tasting. By the way, a cuke that has little yellow on the bottom portion that gets little sunlight is probably okay. We hope this helps! –Almanac editors

A yellow cucumber is usually over ripe. But a pale cucumber can also be caused by a virus, too much water, or a nutrient imbalance. Try adding some aged manure or compost to the soil around the plants.

Cucumbers depend on water and you need to make sure they get a consistent level of moisture. Your pots may be too small to retain the water. Consider transplanting to bigger pots. Cucumbers are also heavy feeders. Add a diluted liquid fish emulsion every other week during the growing season.

Cucumbers need a lot of water. Make sure to water often and add mulch around your plants to keep the moisture in the soil. The wooden garden boxes may dry out quickly in hot weather. Add compost or fertilizer to provide nutrients that the growing cucumbers need.

You’ll want to keep the leaves; they make food for the plant. As for pruning, you do not need to do any if you have a bush cucumber. If you have a vining cucumber that will be trained on a trellis, then pruning is a way to encourage yield and quality fruit. In this case, allow the plant to grow until it forms about 6 or 7 leaves on the main stem. A node is where the leaves connect to the stem. At these nodes, there can also be tendrils, a side shoot (also called a growth point, sucker, or lateral shoot), and a flower or fruit. At the first 5 or 6 nodes counting up from the base of the plant, pinch off the side shoot. [Side shoots are vining branches that grow off the main stem, and will form their own leaves, flowers, fruits, etc.] Also, remove any flowers as they develop on these 5 to 6 lower nodes. Many growers allow just one flower to form on the upper nodes, as well. Depending on the training system, side shoots on the upper nodes are either allowed to grow along a wire or other support, or removed so that there is just one vertical stem.

You can prune the lateral shoots, but do keep the main stem. You may want to do this several times during the growing season.

Female flowers are swollen at the base. This swell is the ovary and a tiny pickle. Note that the early flowers are males so sometimes it's just a question of patience. Both flowers need to be available to bees at the same time without fluky weather interference. Here are pictures of female and male flowers if it helps:
http://vric.ucdavis.edu/pdf/fruitsetproblems.pdf

One crop should produce fruit for about 5 to 6 weeks. The more you pick, the more the vines will produce. Growing vertically increases your yield, too. In terms of the green color of your soil, has it been very wet? Are you using a soluable fertilizer? We'd advise that you add organic matter such as compost and organic mulch to improve your soil.

If you're fertilizing, back off. If you're watering, be sure it's consistent and at the base of the plants, not overhead. Ensure the plants get 6 to 8 hours of sun per day. Otherwise, it's often a pollination issue. You need to plenty of bees which also do not get deterred by fickle weather. You could always hand pollinate. The good news is that cucumbers for pickling should be picked when they are short: 2 to 4 inches long!

There are "vine" cucumbers and bush types. Bush types take up less room and are great for containers. If you have a vine type, you'll need a vertical trellis for the vine to climb--a bamboo trellis would work. In terms of size pot, 1 cucumber needs 1 gallon container. Here's a great source to help you grow your cucumbers and any vegetables in containers: http://aggie-horticulture.tamu.edu/publications/guides/e-545_vegetable_gardening_containers.pdf

Sounds like your plant has powdery mildew.

Try treating with a safe fungicide. To prevent it in the future, try a slow-release fertilizer and make sure they get good sun.

For disease control, avoid picking cucumbers when wet. Also, be sure to water at base of plant and try not to let water splash on leaves. And ensure your plants have good air circulation.