Seeds may not look alive, but they contain some amazing magic. Held dormant by a protective seed coat, the contents of a seed can remain viable for a long time, waiting for the right conditions.
How germination begins
The process of germination all starts when enough moisture and heat are present. These conditions soften the protective seed coat and activate enzymes within the seed. The enzymes convert starchy endosperm into energizing sugars, providing the plant with the energy it needs to grow.
When conditions are less than ideal, seeds may still germinate, but they end up using too many resources to get started, leaving them ill-prepared to thrive. Most of these plants never look or produce as well as they might have.
The process of germination
Once the barrier of the seed coat has been broken and feeding begins, the radicle, or first root, pushes downward into the soil. This primary root nearly always starts out looking like a taproot, but it can quickly change to a fibrous root system as secondary roots form, depending on the plant species. Next comes the first stem, or plumule. and the first set of leaves, or cotyledons, followed by true leaves.
Some seeds, such as eggplant and watermelon, need quite a bit of heat to germinate. They also need long growing seasons to reach full flavor. You can start heat-loving seeds indoors, on heating mats specially designed for seed germination, to get a head start on the growing season. The fact is, different seeds germinate best at different temperatures. While you can certainly try planting earlier or later in the season, this generally ends up being a waste of time and seeds.
I have collected information from a variety of sources to create the table below, showing minimum and maximum temperatures, ideal temperature ranges, and the number of days it takes a species to germinate under ideal conditions at various temperatures. Take a close look at it (email me if you would like a pdf) and note how planting the same seed at different temperatures has a profound impact on how long it takes that seed to germinate.
Note: If you use pre-emergent herbicides, you may be halting germination for many different plants, including the ones you want to grow. Several inches of mulch is a safer choice. Even if weeds sprout in mulch, their stems and roots are not as well attached to the earth, so they are easier to pull.
Seeds don’t use a calendar to tell them when to start growing. Each species has an ideal germination temperature. You can increase the odds of your seeds growing into healthy seedlings by planting them at the correct temperature.
This activity is what turned me on to gardening many, many years ago. It is simple, inexpensive, and a lot of fun for junior gardeners (and the rest of us, too!)
As moisture is absorbed from the sponge into the seeds, they will begin to expand. You will need to monitor the sponge, making sure that it remains moist, but not soggy. Within 2 weeks, if conditions are right, tiny sprouts will begin to emerge!
Encourage your child to draw pictures of how each of the seeds behaves differently and to measure the growth every few days. When the seeds have outgrown their cup, you can transplant them to a sunny location and watch them grow in the garden!
You can grow a surprising amount of food in your own yard. Ask me how!