When a pea seed germinates, it goes through a series of stages: imbibition, activation of enzymes, and radicle and root emergence. Photo by Bogdan Wankowicz, Adobe Stock.
The Science of Germination
Navigating through a few recent hard freezes, the Florida Panhandle’s winter still holds its grip, but a shift is anticipated. As we transition into February and March, the temperatures are likely to soften, offering a milder embrace. Amidst this change, many gardeners eagerly anticipate the surge of new life. This phenomenon is deeply intertwined with the captivating science of germination. It is indeed an intricate process that transforms a dormant seed into a thriving plant.
The Germination Process
Tomato seedlings initially produce cotyledons, serving as temporary nutrient sources, followed by the emergence of true leaves, which engage in photosynthesis and mark the onset of lateral branching. Photo by Baharlou, Adobe Stock.
Germination is when a seed transforms into a seedling, ready to emerge from the soil. But what exactly is happening during this process?
Germination commences with the absorption of water, also known as imbibition. As water is absorbed, the seed swells, softening the seed coat and paving the way for the emergence of the embryo. This pivotal step activates enzymes within the seed, kickstarting the breakdown of stored nutrients, such as starches, into simpler forms like sugars. These nutrients serve as the fuel for the growing embryo until it can harness energy from the sun through photosynthesis.
The first visible sign of this process is the emergence of the radicle, the embryonic root that anchors the plant and facilitates water and nutrient absorption from the soil, establishing a solid foundation for growth. Following radicle development, the embryonic stem begins its upward journey, accompanied by the emergence of cotyledons, or seed leaves, that aid in nutrient storage during the initial stages of growth.
With the growth of leaves, the seedling gains the ability to engage in photosynthesis. This transformative process allows the plant to convert sunlight into energy, fueling further growth and development. The root system continues to expand and branch out, enhancing stability and enabling the plant to absorb water and essential nutrients from the soil.
As the plant progresses through stages of growth, it eventually matures to produce flowers and seeds, completing the life cycle. These seeds, in turn, hold the potential to initiate the germination process anew, perpetuating the cycle of growth and renewal.
Temperature’s Role in Successful Germination
Get a jump start on the spring gardening season by using full spectrum grow lights and heat mats to germinate and grow warm season crops, like tomatoes, indoors. Photo by Molly Jameson.
Temperature is a critical factor influencing the success of germination, serving as a cue for enzymes to initiate their performance. Seeds exhibit distinct temperature preferences, affecting both the likelihood and speed of germination. Understanding these preferences is essential for a thriving garden.
While some seeds, like peppers and tomatoes, flourish in warmer conditions, others, such as lettuce and spinach, prefer cooler environments. It’s crucial to identify the ideal temperature range for your chosen seeds to ensure successful germination. When planning your garden, closely monitor soil temperature and sow seeds at the appropriate time to align with their preferences. For instance, if you’re starting warm season seeds like tomatoes in winter, consider investing in heat mats, a greenhouse, or indoor full spectrum grow lights to maintain a consistent and favorable temperature for germination.
Optimizing germination and ensuring a successful start for your garden hinges on understanding the specific temperature preferences of your crops. Temperature not only influences whether a seed will germinate but also plays a significant role in determining the speed of germination, providing a valuable head start when appropriately managed.
Chilling Requirements for Some Seeds
Echinacea purpurea (purple coneflowers) benefits from cold stratification, a process that involves exposing seeds to cold conditions to break their dormancy and promote germination. Photo by Orestligetka, Adobe Stock.
Some seeds, like black-eyed Susan (Rudbeckia hirta) and purple coneflower (Echinacea purpurea), exhibit a preference for a winter chill through a process known as stratification. This involves exposing seeds to cold temperatures before planting. It mimics the conditions these seeds would experience in their native habitats, breaking dormancy and promoting successful germination. If you’re growing seeds that benefit from cold stratification, consider simulating winter conditions by freezing them for at least a month before planting. Additionally, certain seeds benefit from wet stratification, where they are kept moist during the cold treatment.
While stratification is more commonly associated with perennial flowers and woody plants, there are some vegetable seeds that can also benefit from cold treatment. Carrots and beets may experience improved germination rates with a brief period of cold stratification. Keep in mind that while these vegetables may benefit from stratification, it’s not always necessary for successful germination. Many vegetable seeds are adapted to germinate without a cold treatment.
As we anticipate the arrival of spring, let’s not just see seeds as tiny dormant entities but as intricate biochemical wonders waiting to unfold. Germination is not merely a biological process; it is a testament to the resilience and adaptability of life. It is a reminder of the interconnectedness of all living things and the perpetual cycle of growth and renewal that defines the plant kingdom here on Earth.
Looking to add a nutritional powerhouse to your early season garden this year? One plant that is often thought to be difficult to grow in Florida will surprise many home gardeners. This plant has a long, storied history, having been introduced extensively worldwide, and has invigorated and decimated entire populations. I speak, of course, of the humble potato (Solanum tuberosum), which performs well in our cooler North Florida winter. This member of the Solanaceae or nightshade family can trace its origins to the Andes mountains, where it was discovered by European settlers and brought back to their countries of origin. From there, the potato found success as a food crop and was reintroduced worldwide. This tuber is a big producer, and worthy of a spot in your home garden.
Varieties
The first objective with potatoes is to find a variety that will perform well in our sandy soils and climate. Russets are thought to be the gold standard in potatoes, and while some may be suitable, they are not optimal for Florida gardens. Instead look for some of the later entrants to this market. Several white and red varieties are available which mature quickly and can tolerate environmental conditions in the panhandle. White varieties suitable for this region are ‘Lachipper’ and ‘Sebago’, while the red varieties known to do well here are ‘Red Lasoda’ and ‘LaRouge’. These are compatible with our environment and as such perform well here.
UF/IFAS photo: C. Hutchinson
Growth Practices
A well-draining, slightly acidic, and loose soil will provide the best environment for maximum yield. As with all gardening, it’s best to have your soil tested well before you plant and make any pH adjustments required early. Potatoes grow from “seed” which are essentially smaller potatoes grown specifically to produce more plants. It’s best to acquire these from a reputable seller and avoid grocery store leftovers, as their variety and disease resistance is questionable. Growth happens from the “eye” of the seed, which may be planted with or without growing roots. Cut the seeds into smaller pieces, ensuring there is at least one eye per piece, and allow them to sit in a cool, dark environment for a few days to callous over. They are now ready to plant and should be four inches deep, spaced eight inches apart in three-foot rows. Potatoes require two fertilizer applications, emphasizing nitrogen and potassium specifically, as these pass through the soil easily with irrigation. Apply half of the fertilizer at planting with another application approximately 30-40 days later. Application rates vary and are based on yield goals as well as soil test results so check with your local extension agent to discuss application rates. Keep the potatoes evenly moist but make sure not to flood the rows. Finally, there is a unique methodology with potatoes in that you’ll need to add soil to the top of the row when the potatoes poke through. This is called hilling and is crucial to keep the tubers from turning green and producing a toxin known as solanine.
UF/IFAS photo: C. Christensen
Harvest Time
Your potatoes should be harvestable in about 90-105 days, depending on variety and environmental factors. You’ll be able to tell the plant has matured as the vines will begin to die back naturally. Modern practices have augmented this to include a vine kill which may be performed mechanically or through chemical application. This will force the tubers to mature, allowing the gardener greater control of harvest times and helping to avoid the risk of late-season pathogens. Vine kills are performed between 80-90 days after planting with tubers remaining in the ground for an additional 21 days. All of these time frames are dependent on variety but will produce a more usable and easy-to-store tuber.
UF/IFAS photo: C. Christensen
Potatoes are a worthy addition to the garden and can provide a lot of nutrient-dense food in a small space. There are a few tricks to growing these tubers, but for what they give back, you’ll find it a very rewarding experience. For more information, see these Ask IFAS documents. As always, please contact your local extension agent for additional information on this and any topic regarding your gardens and more.
Looking for a mid-season vegetable to plant in your garden? Look no further, Chinese cabbage is a great option. This cabbage matures quickly and is ideal for growing in winter’s shorter days and cooler temperatures.
Figure: Bok Choy Harvested & Prepared in a dish. Credit: Jieli Qiao, Guiyang, Guizhou, China
Growing Asian vegetable crops in Florida has become an increasing trend over the last decade, mostly due to health benefits and profitability by producers. However, the crop is new to many, who are interested in growing and consuming these vegetables. There are two sub-species of Chinese cabbage. The Pe-Tsai group are the broad leaved, compact heading varieties. The head may be six inches across and either round or cylindrical, in shape. The second group is known as Bok Choy (figure). These are non-heading Chinese cabbage varieties that have several thick, white leaf stalks, and smooth glossy, dark green leaf blades clustered together, similar to the way celery grows.
Again, cooler temperatures are key. Warm temps cause the plant to uptake more calcium, making the heads soft and bitter and may contribute to early seed development through bolting. Chinese cabbage matures in around forty to seventy-five days from planting, depending on variety. There’s no specific requirements to growing this cabbage in Florida, just follow the same soil preparation, liming, fertilization, and cultivation practices that you would use for other leafy vegetable garden crops. The main pests and diseases that occur are leaf blight, downy mildew, aphids, and cabbage caterpillars. Leaf blight and downy mildew usually occur in warmer times of the year, with higher temperatures and rain.
Chinese cabbage is very versatile. It’s great in salads, stir fry, pickled and even as a replacement for lettuce on your favorite sandwich. Enjoy!
Information for this article can be found at the UF/IFAS EDIS Publication, “Bok Choy, an Asian Leafy Green Vegetable Emerging in Florida”: http://edis.ifas.ufl.edu/hs1337 & “Cabbage, Chinese – Brassica Campestris L. (Pekinensis Group)”: http://edis.ifas.ufl.edu/mv036.
UF/IFAS Extension is an Equal Opportunity Institution.
Since 2020, we have delivered timely webinars using Zoom and Facebook Live to reach Gardening in the Panhandle LIVE! viewers. In 2024, we are changing things up just a bit. Due to changes in the way Zoom and Facebook interface we will only be transmitting live through Zoom.
What does that mean for our Facebook viewers? We will still post Events about upcoming programs with links to register for the episode and will continue to share videos after they are uploaded to YouTube (usually this is within 24 hours). Thank you for your patience as we make this change
Below is our lineup for 2024 – we hope you will join us!
In case you missed it, you can watch our last session of Gardening in the Panhandle LIVE! that aired on October 12th by visiting our YouTube Playlist with all the past episodes of our gardening webinars.
We had a great conversation about herbs and cool season edible plants last month and this article compiles the links shared by the expert panel in the episode. Thanks for watching!
Start your fall garden seeds in containers to give them a healthy head start. Photo by Molly Jameson.Seed veggies into starter cell flats using a fine-textured growing medium designed to support seed germination and early seedling development. Photo by Molly Jameson.
Step-by-Step Instructions: Indirect Seeding Fall Veggies
While summer gardens offer a variety of intriguing fruiting crops, I have a special fondness for gardening during the fall season. This preference stems from the reduced pest pressure, decreased need for watering, fewer weeds, and the more favorable cooler temperatures for completing gardening tasks. Although it generally offers a more straightforward gardening experience, achieving success with your fall garden still hinges on applying the right techniques, with one crucial aspect being the care for seeds and young seedlings.
Indirect seeding allows you to nurture your seedlings before they establish their permanent residence in your garden, ensuring their growth into robust, mature plants. Below, you’ll discover a step-by-step guide to indirect seeding and planting for fall vegetables. By following these instructions, you’ll get a head start in cultivating a thriving fall garden that will delight your taste buds.
Seeding into Starter Cells:
While many crops can be started indirectly in starter cells, it’s important to note that root vegetables (such as beets, carrots, radishes, turnips, etc.), peas, and beans are exceptions due to their delicate root systems, which do not transplant well. These particular crops thrive when directly seeded into the garden. Conversely, fall crops that typically benefit from indoor seeding include Brussels sprouts, broccoli, cabbage, cauliflower, cilantro, kale, lettuce, mustards, parsley, spinach, and Swiss chard. For Florida planting dates, transplant ability, and other detailed planting information, see Table 1 in the UF/IFAS publication Florida Vegetable Gardening Guide.
If you use fluorescent grow lights, maintain 2 to 4 inches between the top of the seedlings’ canopy and the fluorescent bulbs. Photo by Molly Jameson.
Begin by moistening a starting mix, which is any fine-textured growing medium designed to support seed germination and early seedling development. Fill seed starter cells with this prepared mix, ensuring a level, flat surface.
Create shallow indentations (2-3 times the diameter of the seed) in the starting mix in each starter cell using your finger and place 1-2 seeds in each cell. (Remove all but the strongest seedling if multiple seeds germinate in the same cell.)
To ensure even coverage and prevent clumping, lightly sprinkle dry starting mix over the seeds.
Label with the crop name, variety, and date.
Mist the surface with water from a spray bottle, pump sprayer, or a hose spray nozzle. Maintain moisture levels, avoiding waterlogging.
Before the seeds germinate, keep them in a temperature-controlled room or out of direct sunlight. Germination time varies, but typically takes 5 to 14 days, depending on the crop, environmental conditions, and seed quality. (For fall varieties, germination is best between 50-80°F.)
As soon as seedlings emerge, move them to a sunny location with more than 6 hours of direct sunlight. If temperatures exceed 85°F, provide afternoon shade to protect them from intense heat. If using full spectrum grow lights indoors (such as a T5 fluorescent light fixture), place seed starter cells at a distance of 2 to 4 inches between the top of the seedlings’ canopy and the fluorescent bulbs for 14 to 16 hours a day.
Continue to keep the starting mix moist but not waterlogged.
Up-potting into Larger Pots:
Up-potting refers to transplanting a young plant or seedling from a smaller container or pot into a larger one. While up-potting most seedling crop varieties into larger pots before transplanting into the garden is beneficial, you can skip this step and directly transplant seedlings from the starter cells into the garden if conditions are favorable (maximum air temperature is less than 86°F). However, keep in mind that young seedlings may be more vulnerable to rain, wind, insects, and animal disturbances. Up-potting into larger pots with nutrient-rich potting mix offers better protection and more time for root development.
When up-potting, carefully extract each seedling using a butter knife to avoid disturbing the roots. Photos by Molly Jameson.
When seedlings develop “true leaves” (the second set of leaves after the initial seedling leaves), it is time to transfer them into larger pots (2″-4″ wide).
To start, fill the larger pots about halfway with pre-moistened, nutrient-rich potting mix designed for vegetables, ensuring good drainage.
After thoroughly watering the small seedlings, carefully extract each from the starter cells, using a butter knife for gentle and precise removal to avoid disturbing the roots.
Being careful not to disturb the roots, place each seedling gently into their halfway-filled pot and add more potting mix until the seedling is secure, standing upright, with all roots covered. There should only be one seedling per pot.
Keep seedlings in a sunny location with more than 6 hours of direct sunlight. If temperatures exceed 85°F, provide afternoon shade to protect them from intense heat. If using full spectrum grow lights indoors (such as a T5 fluorescent light fixture), place seedlings at a distance of 4 to 6 inches between the top of the seedlings’ canopy and the fluorescent bulbs for 12 to 14 hours a day.
Continue to keep the potting soil moist but not waterlogged.
Transplanting into the Garden:
When the time is right, dig a small hole in the garden bed and place the plant, along with the potting mix, in the hole, following the crop-specific spacing requirements. Photo by Molly Jameson.
Once the plants have developed strong roots and reach about the height of their pots, they are ready for transplantation into the garden.
If the plants have been indoors under grow lights, allow them to “harden-off” by gradually exposing them to outdoor conditions for a week. This helps them adjust to wind, direct sunlight, and varying temperatures.
Prepare the garden bed with compost and other soil amendments.
Water the plants thoroughly before carefully removing them from their pots, ensuring minimal disruption to the roots.
For each plant, dig a small hole in the garden bed and place the plant, along with the potting mix, in the hole, following the crop-specific spacing requirements (see Table 1 in the UF/IFAS publication Florida Vegetable Gardening Guide).
Cover the roots and maintain consistent soil moisture, avoiding waterlogging.
In summary, mastering the art of indirect seeding and planting fall vegetables can greatly improve your chance of a successful harvest. From carefully sowing your seeds in starter cells to up-potting and ultimately transplanting into your garden, each step is a vital component of the process. So, roll up your sleeves, get your hands dirty, and witness your fall garden flourish. Happy gardening!
