Vegetable gardens can be started by planting vegetables that have already started growing. However, many gardeners prefer to grow their vegetables from seeds. These seeds often must be planted within a specific time frame and prefer soil that has a certain temperature. Fortunately, by growing from a seed, a vegetable gardener can learn how to harvest the vegetable seeds and use them to grow the same vegetables next year.
Vegetable seeds are usually no different from other plant seeds. The seed consists of a protective outer coating, a plant embryo and an endosperm to nourish the plant embryo.
Vegetable plant seeds have different life spans. When the seed has exceeded its lifespan, the seed will not grow when it is planted in the ground. Onion seeds last one year. Okra and parsley seeds last two years. Asparagus, soybeans, beans and carrots lasts three years. Beets, mustard, pumpkin seeds, cauliflower and cowpeas last four years. Broccoli, cucumber, cabbage, cantaloupe, kale, eggplant, lettuce, radish, celery, spinach and collards last five years. How long the vegetable seeds last is also determined by the temperature at which the seeds are stored and how moist the storage area is, since moisture can cause the seeds to germinate.
Seed weight can vary. When placed on a scale, one ounce equals 80,000 celery seeds but only 15 mustard seeds. Very small seeds might be blown away by strong winds, and larger seeds are more likely to be eaten by birds.
When choosing which vegetables to plant, it is helpful to know the temperatures that particular vegetable plant seeds prefer. Beet seeds prefer 50 to 85 degrees. Asparagus seeds prefer 60 to 85 degrees. Broccoli seeds prefer 68 to 86 degrees.
Many vegetable gardeners would like to continually regrow the same vegetables by using the seeds that are produced by their vegetable plants. This is possible when the vegetable plant is able to fertilize itself. Otherwise, two different plants, male and female, must be planted nearby so that they can pollinate each other. Other vegetables need time to develop flowers in order to later produce seeds, like the lettuce plant. Sometimes, these plants cannot be consumed when they start flowering.