Knowing when to start seeds indoors for zone 6 (or any zone) will help you to plan for your garden’s success in the upcoming growing season. Despite zone 6 having a relatively short growing season, using a little planning, and starting your seeds yourself, can extend your growing abilities quite a bit.
For many, the most challenging part of starting seeds is when to do it and the planning around it.
How do I Know When to Start Seeds Indoors?
No matter where you live, it’s important to understand the growing climate you are in. To help you in getting started, and planning your growing season, you need to find out 3 important pieces of information. Your plant hardiness zone, your average last frost date, and your average first frost date will help you plan successfully.
USDA Hardiness Zones
The USDA Hardiness Zones denote the average minimum temperature for a given area in the United States. As a general starting point, they can be very helpful when getting a broad idea of the type of growing you can do.
Your USDA zone will primarily determine the types of plants you can over winter and raise year after year on your property.
For example, here in zone 6, our average low is between -10 degrees F, and -5 degrees F.
In these temperatures I’m not going to have any luck growing a lemon tree year round. However, many varieties of apple, pear, and even some hardy peach trees thrive here!
Last Frost Date (or Frost-Free Date)
The last frost date is the average date of the last spring frost in your location. This marks the official beginning of gardening season! (Though it begins sooner for many avid gardeners).
Finding our your last frost date will determine your gardening schedule for the year.
To find out what seeds to start when, you will count back from your last frost date by the number of weeks advised on your seed packets. This will determine when to start your seeds, when to transplant them outside, and when to sow a second crop.
For example, my tomato seed packages advise that the seeds should be planted 6-8 weeks before my last frost date. Then, the tomatoes can be planted out after the danger of frost has passed.
To determine what your last frost date is, you can enter your zip code here.
Zone 6 exists in places across the country, so it’s important to find a specific last frost date for your area. Finding a more specific snapshot will help to account for differences in microclimates across the zone.
For example, a simple search of “zone 6 last frost date” tells me that the average for zone 6, is April 1-21st…
However, when I check for my specific zip code, I find that my last frost date is actually May 7th.
First Frost Date
Your first frost date is the average first day that frost will return to your area. You can also determine your first frost date here.
My first frost date is October 9th which gives me a growing season of 154 days.
This means that after May 7th, but before October 9th, I can grow frost tender fruits, vegetables, and herbs.
Before and after those dates, I’ll need to use season extenders, or else choose different crops then.
I can choose to grow frost hardy crops during the cooler weather.
These three factors will provide you with what you need to know to successfully plan your garden season.
When to Start Seeds Indoors – Zone 6
The calendar below shows (in green) when to plant seeds directly into your vegetable garden.
It shows (in blue) when to start seeds in doors, and (in dark blue) when to transplant your seedlings outside.
Sometimes the bulk of the leg work in planning your vegetable garden for the year is making a plan.
Luckily, I just went ahead and did that for you below!
You’ll notice that some vegetables need to be planted outside before the frost-free date. This is because some root vegetables like radishes and peas, as well as leafy greens, and broccoli will even taste better after a light frost. These plants are also prone to bolting, or going to seed, in warmer temperatures.
Other plants, like tomatoes, peppers, melons, and squash, prefer high temperatures to thrive. These should not be planted out until after the frost-free date, to prevent damage.
A light freeze (or frost) is between 29° to 32°F (-1.7° to 0°C) and will kill tender plants such as tomatoes and zucchini.
A moderate freeze is between 25° to 28°F (-3.9° to -2.2°C) and is widely destructive to most vegetation, including some damage to your cold hardy crops without cover.
A severe freeze is 24°F (-4.4°C) and below. You can expect heavy damage to most garden plants.
Starting Seeds Indoors vs Direct Sowing
You’ll notice that some of the vegetable plants on the calendar like carrots, kale, and peas are marked with “direct sow outdoors”. This type of seed prefers to be planted directly in the garden to grow there.
Direct sowing is mostly for vegetables that prefer to avoid their roots being disturbed. For example, root vegetables do best direct sown into the garden. Another example are melons and squash that are fast growing, don’t need a head start, and prefer to remain undisturbed.
Other plants on the calendar are marked with “start seeds indoors” and then “plant outside”.
Starting seeds indoors allows you to get a jump start in early spring for your garden. These seeds, started early, are able to get a strong head start before being exposed to pests.
Tomato seeds, pepper seeds, and cole crops like broccoli and cabbage should be started indoors.
Also, plug trays of seedlings are much easier to keep an eye on than the rows that need managed outdoors.
Indoor seed starting provides a great environment to manage those specific needs of your delicate seedlings.
For fall planting, starting those seeds indoors will be the best way. The most important factor for the success of many fall crops is the temperature. During the mid July heat, they won’t thrive as well as they will in the more mild temperatures indoors.
Transplanting After You Start Seeds Indoors
After putting in the work to get your seedlings up and growing, planting them outside can feel a little daunting.
Luckily, there are a few things you can do to help prevent transplant shock or any other losses after you start seeds indoors.
Row covers can provide great peace of mind for new gardeners. Row covers can prevent insects from causing damage to young plants, especially during late spring when they come out heavily. They are also helpful at diffusing harsh sun exposure, and can provide slightly more mild temperatures.
This type of season extender is a great way to give your seedlings more than enough time to acclimate to the garden without too much shock.
No matter what you use to introduce your seedlings to the garden, you’ll need to make sure to harden off your young plants.
Hardening off seedlings is simply a slow introduction to the elements of the outdoors. If you put seedlings from the comfort of your home or greenhouse directly into the garden, you’re likely to lose all of your seedlings, and hard work.
The sun, wind, and temperature fluctuations can often be too much on young plants, so be sure to have a plan for getting them acclimated.
Putting in the effort to start seeds indoors for my zone 6 garden is always a welcome return to homestead activities during our Ohio winters.
Hopefully you are able to get a good start to your growing season, save money on seedlings, and get a head start on your garden!
Happy gardening, friends!