Temperature and Humidity
Different plants have different recommended germination and growing temperatures. Always make sure that you check each plant’s growing requirements--especially minimum and maximum temperature levels. Keep in mind that specific varieties of plants may have different requirements.
Indoors or out, most fruits and vegetables grow best between 55 and 85ºF. Try to keep your temperature around 75ºF if possible during the day and around 65ºF at night. If you are growing indoors, remember that plants dislike drafts.
Most people won't run into humidity problems (unless they live in a rain forest or desert). If the air is too dry or wet, you might want to invest in a humidifier, dehumidifier, or a combination unit. If your plants are too dry, misting them with water will help raise the relative humidity.
Keep in mind that too much humidity and warm temperatures can be conducive to the growth of many fungal diseases (see pests and diseases). Maintaining proper environmental conditions, using sterile supplies, and paying quality attention to your plants is the best way to ensure proper growth and prevent diseases.