This time of year we get a lot of questions about how soon we can plant our vegetable seeds and seedlings. Let’s separate fact from fiction and all the “old wives tales” that so many gardeners swear by. Here’s what you need to know.
The key to planting seeds and seedlings this spring is knowing when Central Arkansas will experience its final frost of the season. According to the Farmer’s Almanac, the average last frost date is April 8th. However, anytime you’re dealing with Mother Nature and living plants, there’s still an element of risk that’s inherent to raising a garden.
So how soon is too soon? The correct answer is as soon as your ground can be worked, which means completely thawed from any remnants of ice and reasonably dry so the soil can be tilled without clumping. If you have a small garden plot, or a raised bed, we suggest double digging with a spade to loosen the soil to a depth of 14 inches. It’s the perfect time to add additional Lady Bug Revitalizer Compost or Good Earth Potting Soil to freshen up the soil and replace nutrients spent from last years garden. Now that your seed bed is prepared, you can safely plant onion sets, English peas and spinach. Cooler soil temperatures don’t inhibit germination of these frost tolerant vegetables, in fact they thrive in colder weather.
From seedlings and seeds, lettuce, beets, radishes, cabbage, broccoli, cauliflower, collards, kale, carrots and potatoes can be safely planted two weeks prior to the last frost date. But if you’re like me, there’s no waiting when the temperatures in February and March are consistently in the 60′s. These vegetables can withstand a light frost, and acclimate well to colder temperatures. As a side note, it’s very important to harden your seedlings. Vegetables purchased as seedlings were all started in greenhouses, and may not have been exposed to any temperature less than 50 degrees, prior to you taking them home. It’s best to gradually expose them to the colder temperatures (this will harden or acclimate them). Going directly from a warm greenhouse one day to a 37 degree night in your garden, will most certainly shock the plant. But, that’s part of the risk we’re taking by getting slightly ahead of our 2 week window. Considering the other extreme, Spring can be short lived in Arkansas, and we often experience daytime highs in the 70’s even 80”s, so it’s very important for lettuces and the brassica vegetables (also called cole crops and include cabbage, lettuces, broccoli, cauliflower, mustards and brussel sprouts) to be started early, because they are prone to bolt, which means they prematurely flower and go to seed if temperatures are too warm.
What are termed “later vegetables” have no tolerance whatsoever of temperatures that approach the freezing mark. Therefore we have to hold off on planting tomato seedlings along with peppers, eggplant, squash, cucumbers, beans, okra, corn and melons, until after the threat of frost is passed. In Central Arkansas, Zone 7, that date again is April 8th. By this time the ambient soil temperature is consistently above 60 degrees, which means all of the dormant micro-organisms in your soil are waking up. These tiny bacteria represent the coup de gras with respect to the fertility of your garden. They are constantly at work converting organic matter, transforming vitamins and minerals into simple compounds that the plant roots can easily assimilate. Christopher Byrd described this arena as the “secret life of plants.” Espoma’s Bio-Tone contains over 15 different beneficial bacteria including 2 strains of mycorrhizael fungi, and Super-Thrive, a liquid concentrate of vitamins and enzymes are both excellent soil amendments that need to become a part of your annual garden regime. You can also accelerate germination time by soaking your seeds 24 hours before they are to be planted in a nutrient solution containing seaweed or a root stimulator concentrate. We also recommend banding fertilizer, which means placing fertilizer directly in the prepared row along with your seed, or adjacent to the seedling. Here’s where we have to be careful; too much nitrogen can damage young sprouting seeds and seedlings so Espoma’s Garden Tone with organic nitrogen is an ideal choice.
The optimum growing conditions in early Spring are well worth the risk of having to contend with lingering colder temperatures. Keep in mind a heavily watered soil allows your plants to tolerate cold more so than dry soil conditions. And the insulation offered by a frost blanket, such as N-Sulate, can provide as much as 3-5 degrees of additional frost protection. Finally, a soil that is biologically alive, i.e. high in organic matter, is much more responsive to the radiant heat from the sun, optimizing the growing conditions for your vegetables. The vitality and balance of the biology in the soil is passed on directly to the plants, rewarding you with fresh, great tasting home grown tomatoes and other vegetables, that can only come from your garden.