Starting Seeds Indoors & A Vegetable Growing Schedule for Zone 6

January 22, 2025

Starting seeds indoors is a great way to jumpstart your gardening season, especially in regions with a shorter growing period like Zone 6. By starting your plants indoors, you get a head start on the growing season and can nurture your plants before they are exposed to the elements. Plus, it gives you the chance to grow varieties that may not be available as young plants at the nursery.

This guide will walk you through the process of starting seeds indoors and give you a growing schedule tailored for Zone 6, which typically experiences a last frost date between April 15 and May 15.

Why Start Seeds Indoors?

Extended Growing Season: Starting seeds indoors allows you to grow plants that need a longer season than Zone 6 can offer by giving them a head start indoors.
Better Control: You have more control over the conditions (temperature, light, and watering) than you would if you planted seeds directly in the garden.
Variety: Starting seeds indoors opens up a greater variety of plants that may not be available locally as seedlings.
Cost-Effective: Seeds are often cheaper than buying established plants, making starting from seed a more affordable way to garden.

Supplies You'll Need

Before you get started, make sure you have the following essentials:

Seed Starting Trays: These can be as simple as a shallow container with drainage holes or a specialized seed tray.
Seed-Starting Mix: Use a light, sterile seed-starting mix designed for germinating seeds. Regular potting soil is too heavy for seedlings.
Seeds: Choose varieties suited to Zone 6 and your growing preferences (check the seed packet for details on when to start and transplant).
Grow Lights: Seeds need 12-16 hours of light a day. If you don’t have enough natural light, invest in some grow lights.
Heat Mat (Optional): Some seeds (like peppers and tomatoes) benefit from warmth to germinate, so a heat mat can speed up the process.
Watering Can or Spray Bottle: Gently water your seedlings to avoid disturbing the soil.

Step-by-Step Guide to Starting Seeds Indoors

Step 1: Plan Your Seed Starting Dates

Starting seeds indoors requires careful planning, especially when considering the last frost date in your zone. In Zone 6, the last frost typically occurs between April 15 and May 15. Counting backwards from that date, you can determine when to start each type of seed indoors.

Refer to the seed packet for the “days to maturity” and “recommended indoor start time.” For example, tomatoes need to be started 6-8 weeks before the last frost, while peppers might need 8-10 weeks. Here’s a basic guideline to help you get organized:

Cool-Season Crops (like broccoli, cabbage, and kale) can be started indoors 6-8 weeks before your last frost date.
Warm-Season Crops (like tomatoes, peppers, and eggplants) should be started indoors 8-10 weeks before the last frost.

Step 2: Prepare the Containers and Soil

Fill your seed trays or containers with seed-starting mix. Moisten the soil lightly before sowing seeds to avoid disturbing the delicate seedlings once they start growing. Make sure the containers have drainage holes to prevent the seedlings from getting waterlogged.

Step 3: Sow the Seeds

Follow the instructions on your seed packet for sowing depth and spacing. Generally, smaller seeds are planted closer to the surface, while larger seeds are buried a bit deeper. Label each container with the type of seed and the planting date.

Step 4: Create the Right Environment

Seeds need warmth and moisture to germinate. Place your containers in a warm area or use a heat mat. Most seeds germinate best at temperatures between 65°F and 75°F (18-24°C). Cover the containers with a clear plastic lid or a plastic wrap to maintain humidity until the seeds sprout.

Once seeds have germinated, remove the cover and place your seedlings in a spot with bright light—ideally, 12-16 hours of light a day. If you don’t have enough natural light, use grow lights positioned 2-4 inches above the seedlings.

Step 5: Watering and Care

Water your seedlings regularly, but be careful not to overwater. The soil should remain moist but not soggy. Gently water with a spray bottle or watering can to avoid disturbing the delicate seedlings.

Once seedlings develop their first set of true leaves, you can begin fertilizing with a diluted liquid fertilizer to give them an extra nutrient boost.

Step 6: Hardening Off

Before transplanting seedlings into the garden, it’s essential to “harden them off” to prevent transplant shock. About a week before your last frost date, start acclimating your plants by placing them outside for a few hours each day. Gradually increase their exposure to sunlight and outdoor temperatures over the course of a week.

Zone 6 Vegetable Growing Schedule

Now that you know how to start seeds indoors, here’s a suggested planting schedule for Zone 6, taking into account the region’s typical last frost dates (April 15 to May 15) and the needs of various vegetables.

Vegetables:

Tomatoes

Indoor Start (Weeks Before Last Frost) 6-8 weeks

Outdoor Transplant (After Last Frost) 1-2 weeks after last frost

Direct Sow Outdoors No

Peppers

Indoor Start (Weeks Before Last Frost) 8-10 weeks

Outdoor Transplant (After Last Frost) 2 weeks after last frost

Direct Sow Outdoors No

Eggplant

Indoor Start (Weeks Before Last Frost) 8-10 weeks

Outdoor Transplant (After Last Frost) 2 weeks after last frost

Direct Sow Outdoors No

Broccoli

Indoor Start (Weeks Before Last Frost) 6-8 weeks

Outdoor Transplant (After Last Frost) 2-3 weeks before last frost

Direct Sow Outdoors No

Cabbage

Indoor Start (Weeks Before Last Frost) 6-8 weeks

Outdoor Transplant (After Last Frost) 2-3 weeks before last frost

Direct Sow Outdoors No

Cauliflower

Indoor Start (Weeks Before Last Frost) 6-8 weeks

Outdoor Transplant (After Last Frost) 2-3 weeks before last frost

Direct Sow Outdoors No

Lettuce

Indoor Start (Weeks Before Last Frost) 4-6 weeks

Outdoor Transplant (After Last Frost) 2-3 weeks before last frost

Direct Sow Outdoors Yes (early spring)

Spinach

Indoor Start (Weeks Before Last Frost) 4-6 weeks

Outdoor Transplant (After Last Frost) 2-3 weeks before last frost

Direct Sow Outdoors Yes (early spring)

Kale

Indoor Start (Weeks Before Last Frost) 4-6 weeks

Outdoor Transplant (After Last Frost) 2-3 weeks before last frost

Direct Sow Outdoors Yes (early spring)

Carrots