What you should know about:

TOMATOES
1. A soil temperature of 70 to 75 degrees during the day and 60 to 65 degrees at night is ideal.
2. Tomatoes do well when mulched and protected by row covers.
3. Spacing is critical with tomatoes. Although a plant of a compact variety does just fine when situated only 2 feet from its neighbor, plants of a large, rambling, late variety won't do at all well at that distance.
GREEN PEPPERS
1. An extensive root system allows peppers to efficiently use water in the soil, so they don't need watered as often as less efficient crops such as cabbage.
2. When peppers don't have enough potassium, they grow slowly and produce bronze-colored leaves with spots along the veins. The fruits of potassium-starved plants are small and few in number.
3. Leave 18 to 24 inches between pepper plants. With expensive or large plants, it is wise to leave more room to get a generous yield.
CORN
1. Because corn is pollinated by the wind, design your corn patch to allow the greatest possible transfer of pollen. If you are planting only a small amount of corn, arrange it in several short rows to form a block rather than in a few longer rows.
2. Corn needs heat to thrive. If the temperature drops to about 54 degrees, the plants can't photosynthesize.
3. Corn root systems can extend down 3 feet or more and spread out 3 to 4 feet. So space the plants widely, to ensure that the roots of the plants don't compete with one another.
CUCUMBERS
1. Cucumbers can be grown close together -- vining varieties should be planted in hills spaced 3 feet apart, with three plants to a hill.
2. Cucumbers can grow very fast -- they may increase in size by 40 percent in only 24 hours.
3. Cucumbers should be stored at 45 to 50 degrees with a relative humidity of 90 to 95 percent. They will keep for 14 days under these conditions.
SQUASH
1. There is no secret to growing summer squash. Just provide rich soil, plenty of sunshine and adequate water, and within two months of planting, you'll be harvesting abundant quantities.
2. Because of the compact, bushy growth of summer squash, hills can be spaced as close together as 3 feet, with three plants per hill.
3. Summer squash must be watched carefully because the fruits grow very fast. Within four to eight days of pollination, a summer squash is ready to pick, and the warmer the weather, the faster it will grow.
Source: The Book of Garden Secrets