By Julia Welzen, Community Engagement Coordinator
Spring is just around the corner, and gardeners everywhere are itching to dig in the dirt. Hamilton East Public Library’s Seed Library opened March 1, but before you leap outside with trowel and seeds in hand, make sure you have a plan for gardening success.
Frost Dates & Plant Hardiness Zones
As a gardener, there are two important dates you must be mindful of: the last frost date and the first frost date. The last frost date is considered an all-clear date when frost-sensitive plants can be safely planted outdoors at the start of the growing season. Meanwhile, the first frost date in the fall is when those plants usually die. While some plants don’t mind the occasional cold temperature (peas, kale, carrots), many plants will wilt or die at even a whisper of frost (like tomatoes and basil). Others won’t germinate until they have consistent temperatures. The seed packet or the plant tag should always tell you when to plant it.
While estimated dates are given for both the last and first frost dates, keep in mind that they are averages, not absolutes. As a gardener, you have to watch the weather forecast and the actual conditions to determine what you think the best course of action will be (including covering your seedlings if there is an unexpected cold snap). In Hamilton County, the average last frost date is April 30, but cautious gardeners often use Mother’s Day (May 14 this year) as the all-clear date for frost-sensitive plants.
The United States is divided into plant hardiness zones based on local climate and even microclimates. The United States Department of Agriculture maintains an interactive Plant Hardiness Map, which helps gardeners determine what plants will thrive in their climate and gives an estimated last frost date. Hamilton County is in Zone 5b/6a. All the plants in the Seed Library will thrive locally, but if you order seeds or purchase plants, be sure to check what the recommended hardiness zones are.
So, when can I plant my seeds?
Research, research, research! Each plant has its own unique needs, and you may or may not have the space, equipment, or time to meet all of those needs. Read up on blogs or watch any of the wealth of videos out there on gardening, including the HEPL Seed Library playlist. Here’s some of the situations you may encounter:
Starting seeds indoors before the last frost
Peppers, tomatoes, eggplant, some herbs, and several flowers require a longer growing season than we have in Indiana, so they will need to be started indoors several weeks before you acclimate them to the outdoors. This may require purchasing some equipment and may take up some space, so this might not work for your lifestyle. Learn more about starting seeds indoors from Kathy in the video below or in this blog.
Early spring/frost tolerant plants
Some plants, like carrots, peas, lettuce, and several varieties of greens, don’t mind cool weather and light frosts. The instructions will tell you either “plant when soil can be worked” (no longer frozen) or to plant a certain number of days or weeks before the last frost.
Native plant seeds requiring cold, moist stratification
This only applies to flowers native to Indiana, which require an artificial process (cold, moist stratification) to mimic an Indiana winter before they can germinate in the spring. If these seeds are planted early enough (direct sown in late fall or winter sown), you can skip the cold, moist stratification process.
Planting seeds after the last frost
Many plants (most flowers, herbs, and vegetables) can be planted directly outdoors after the last frost. Watch the weather forecast and determine what timeframe will work best for you.
Remember: Research!
While that was just a very brief overview, always remember to research your plants before you actually plant them. Blogs, videos, and social media are full of gardeners who love to share their knowledge and invite questions. Before you check out seeds from HEPL’s Seed Library, review our Seed Library Guide, and then stop by to make your selections. Happy Gardening!
