Homestead and Gardening

When to Start Seeds Indoors

You purchased your seeds from the best seed companies, but how do you know when to start seeds indoors? Do you start them all on the same day and hope for the best? Do you stagger them over the course of the entire year? Does it matter what zone you live in?

If you’re not sure about the answers to these questions, I am here to help.

You can use this as a guide for understanding how to plan your seed starting, and have your plants ready to put in the ground.

Here’s what you need to know about: When to Start Seeds Indoors.

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1. Know Your Plant Hardiness Zone

Your plant hardiness zone can tell you a thing or two about when to start seeds, but it’s primarily useful for determining what plants will survive in your area for overwintering. For example, where I live in zone 6a I can’t overwinter Rosemary. Though it is a perennial, our winters get too cold for it to live outside.

This is what the map looks like and you can figure out your zone by visiting the USDA Plant Hardiness Zone Map.

One of the most beneficial things to knowing your zone is finding bloggers and social media influencers who live in your same zone. If a trusted Instagram gardener or blogger is beginning their tomato seeds in March and they live in the same zone you do, it can give you a good indication of when you should be starting yours.

Some seed packets will tell you when to start a seed based on your hardiness zone.

Knowing your zone can also help you understand how long your growing season is. There are some things that require a long time to grow before they’re fully mature. If you live in an area with a short growing season, that may not be for you. This leads me to…

2. Know Your First and Last Frost Dates

selective focus photography of white petaled flower plant
Photo by Alissa Nabiullina on

It’s really important to know your first and last frost dates where you live. For us, our last frost date (the last day in Spring when we can expect it to frost) is the middle to end of May. Our first frost date, or the date when it will start being too cold for tender annuals is the beginning of October. That means we have about 4.5 months to grow our plants.

You can find out your expected frost dates by visiting the Farmer’s Almanac online. Put in your town or city and zip code, and it can give you a predicted first and last frost date.

Just for fun, I looked up the first and last frost dates of Orlando, Florida. If you live in an area with a warmer climate, your growing season is much longer than those of us who live in the northern United States. The last frost date in Florida is January 30 and the first frost date is January 3. That means you can grow tender plants for most of the year. However, I would imagine when growing plants in Florida you would contend with problems on the other end of the spectrum by dealing with high temperatures.

Most seed packets will tell you how many weeks before the last frost you need to start your seeds. So if you live in zone 6a as we do, and your seed packet says to start seeds 8 weeks before the last frost (in my case, May 15), you’re going to want to start them in mid-March.

3. What Do Your Seed Packets Say?

Your seed packets can be an absolute wealth of information. Many seed packets will tell you:

  • How long to plant before the last frost
  • Days to maturity
  • Best soil temperature
  • How long until germination

The first thing to look for is the recommended time to start seeds indoors on the seed packet. The one pictured above says to start seeds 2-4 weeks before the last frost. Again, for me, that would mean going to my calendar and counting back 2-4 weeks from May 15.

You may live in a warmer or colder area, which means your seed starting date would be different.

Days until maturity can be very helpful for understanding how long something needs to grow until it’s ready to harvest. If you have a very short growing season, you may want to start certain plants earlier so they can fully mature before the first frost comes again. People who have longer growing seasons may not need to start them as early.

The temperature of the soil may not seem particularly important but it is! This can give you a good indication of when the plant will do well outside. Some plants prefer it to be cool (broccoli, lettuce, onions) while others prefer warm soil (green beans, eggplant, tomatoes). Your plants that like the cool weather can often be directly sown as soon as the ground is workable, but it might help to give them a jump start indoors depending on what you’re growing.

How long a seed takes to germinate can also affect when you start a seed. Lavender seeds are notoriously difficult to start because they need to go through the process of stratification and they have a long germination period. You may want to start lavender earlier in the year so you’re ready to transplant sooner.

4. When in Doubt — Try 6-8 Weeks Before the Last Frost

What do you do when the seed packet doesn’t have any information or you were gifted seeds without the original seed packet? Or people saved seeds and shared them with you?

A good rule of thumb for many warm-weather plants is to start them 6-8 weeks before your last frost. This is a good safe bet for many seed varieties that require warm weather to survive.

You can also look up the seeds on the original website. Sometimes seeds will have more information listed online than they do on the seed packet (I’ve noticed this happening with Baker Creek Seeds, for instance).

You can also look up information about seed types. If you want to know when you start a pack of tomato seeds, you can always look up the general consensus in a quick Google search. It may not apply to your specific tomato variety, but it’s very likely to.

5. Direct Sow, Frost Resistant, and Indoor Seed Starting

Some seeds can survive in frosty weather and others cannot. Some seeds can be directly sown in the ground and do not need to be started indoors first. Some seeds need a few weeks’ headstart before they can be dropped in the ground and others are terrible at transplanting and must be directly sown in the dirt.

Here is a list of some plants that can be sown directly sown in the ground, even before the last frost. (Note: This doesn’t mean they can withstand the coldest temperatures, but they do well in cool weather… If something is “frost resistant” you’re talking around 20-25 degrees fahrenheit, not -10)

  • Sweet peas
  • Broccoli
  • Cabbage
  • Cauliflower
  • Carrots
  • Onions
  • Turnips
  • Parsnips
  • Spinach
  • Lettuce
  • Kale
  • Radishes
  • Swiss Chard
  • Dill
  • Caraway

Many of these cool-weather plants can be started a few weeks before you put them out in the garden to give them a jump start on the season, but can be started directly in pots or in the garden if you live in a place that has a long enough growing season.

There are also seeds that can be directly sown in the dirt that are not cold-resistant but can grow to maturity in the soil. These include:

  • Beans
  • Squash
  • Zucchini
  • Corn
  • Cucumber

Some seeds don’t transplant well. So even if you want to get a jump on the growing season, it’s unlikely that they will do well. Among these garden plants are:

  • Carrots
  • Corn
  • Beets
  • Turnips
  • Peas
  • Melons/Squash can be transplanted, but they don’t have a high success rate
  • Okra
  • Cilantro
  • Dill

What is Winter Sowing?

If your favorite garden enthusiast is looking for milk jugs in February — you’ll now know why. They’re probably winter sowing.

What is winter sowing you might ask?

Winter sowing is sowing seeds outdoors in the middle of the cold season in containers. Containers might include milk jugs, planters, pop bottles, plastic salad containers, or anything else with a clear top that allows sunshine and enough space for the plant to grow. These containers act as mini green houses to your plants.

Winter sowing is a low-risk, inexpensive, and low-stress way of starting seeds. There’s a huge following for this method, and there’s even a cool Facebook group dedicated to it that I am a member of.

I used winter sowing last year and had so much fun with it. Personally, I wouldn’t use this method for all of my garden vegetables. I felt like my peppers and tomatoes were behind the seedlings we bought at the local nurseries. However, I think this will work great for things like broccoli, cauliflower, and other cool-weather plants.

Cold Stratification and Winter Sowing

Winter sowing is a really great way to start seeds that need cold stratification before they can germinate well. Common plants that need cold stratification include:

  • Lavender
  • Bergamot
  • Goldenrod
  • Poppy
  • Sage
  • Artichokes
  • Rosemary
  • Milkweed (great for butterflies!)

When Can You Start Winter Sowing?

Part of the beauty of winter sowing is that you have a lot of freedom about when to start your seeds. The seeds won’t grow until they’re ready, so it’s not as vital to start them at a particular time. However, you don’t want to start winter sowing your seeds when your temperatures are greatly fluctuating and you’re getting above freezing temps regularly. This means you may have tender plants sprouting before the correct time that will die if left outside.

Seeds that need that cold stratification need that extra time in the cold. So for these, you won’t want to wait until the temperatures are starting to rise to put them in your milk jugs. Try to put them out at least 4-5 weeks before temps start coming above freezing.

Remember to keep an eye on the maturity time of your plants. You can start your winter sowing in late spring and even summer if they have enough time to grow to full maturity before the end of your growing season.

Organize Your Seeds and Seed Dates

If you want to save yourself a lot of scrambling and memory lapse issues, I would recommend organizing your seeds and your seed starting dates ahead of time.

I used a plastic photo box kit to organize my seeds. I love that I can have a selection of seed packets in individual boxes. This really simplifies the process.

I spent half a day separating my seeds into the month I plan on planting them. I gave myself little notes like “direct sow” or “winter sowing” for seeds intended for this purpose.

Then I wrote down each week between now and the end of spring for when I needed to plant my seeds. It looks something like this:

People remember their seed starting dates in different ways. I use a notebook, but it’s also useful to write them in:

Seeds for Generations also offers a free garden planning calendar that you can use to know when to start your seeds. Just put in your frost dates and it will help you know when to start over 40 varieties of plants.

What Are the Best Seed Companies?

I have been trying out a lot of seed companies this year and last year when I tried winter sowing. I have mostly used heirloom seeds because I want the option to save seeds, but there are tons of great seed companies out there. Here are some of my favorites:

Full disclosure: I have partnerships with High Mowing Seeds and Seeds for Generations.

Seeds for Generations

Seeds for Generations is a small family-owned company and an affiliate of ours. I purchased these seeds last fall and I had very good success with the seeds that I planted. The radishes came up fast and hearty and the lettuce germinated well. I will try out the purple broccoli and leeks in the upcoming spring and report back.

I love supporting small businesses and I was so happy with the results of the seeds I planted. I am planning on making a bigger order soon to add to my seed collection so I will have more to tell you about by next summer.

They do not sell GMO seeds, but some of their seeds come from other suppliers. If you’re searching for organic, please make sure you buy the ones listed as organic. They have a good number of these as well.

Here are a few of the radishes we grew fall of 2022.

This year we bought quite a few seeds from them and I am excited to see how they do this growing season.

Baker Creek Seeds

Baker Creek Seeds is an extremely well-known heirloom seed company. I remember getting their catalogs years ago and wanting to purchase their seeds, even without any setup to grow them or anywhere to plant them (we were renting a place at the time without access to starting a garden).

If you look for heirloom seeds you will likely come across Baker Creek Seeds.

They offer a ton of varieties of plants and a lot of people love them.

I ordered quite a few seeds from them last year and had great success with the majority of them. I was not as successful with the watermelon and zucchini seeds that I planted, but I’m not sure if Baker Creek is to blame or if it was a strange year for melons in general (it seemed to be).

Baker Creek Seeds are not organic, but they are GMO-free.

High Mowing Seeds

High Mowing Seeds offer ALL organic seeds and are a very reputable company. A lot of gardeners like this company and promote their seeds.

A lot of organic gardeners like using organic seeds because they feel these plants will survive without the use of herbicides and pesticides in their gardens.

True Leaf Market

True Leaf Market was recommended to us, and my Dad who I co-garden with is interested in purchasing some seeds from them.

Not all of their seeds are heirlooms, but they do have a large collection of heirloom seeds to choose from. They have some organic seeds for sale (512 seed varieties that are both organic and heirloom seeds).

This year we purchased from them lavender, asparagus, and mini cucumbers from True Leaf Market.

Mary’s Heirloom Seeds

Mary’s Heirloom Seeds is another small company that was recommended to us. Her company offers a lot of advice and help, and they state they’re “only a phone call away.” Located in Texas, this seed company sources all its seeds from small family farmers and seed growers in the US.

We had a small issue with a seed order we made with this company and they quickly remedied the problem and sent a replacement seed packet while allowing us to keep the original one sent. I really like this business and they offer a lot of free information for gardeners as well.


MIgardener is a seed company recommended several times over. This business began in 2011, and their entire line is heirloom and organic. I also noticed that every seed they currently offer is $2.00, a great price!

Southern Exposure Seed Exchange

Southern Exposure Seed Exchange had a lot of support as well. I appreciated in their FAQ section how transparent they were with their product, including mentioning that they do not use chemical treatments on their plants but that they did use diatomaceous earth (DE).

DE is considered organic, but it’s nice to know exactly what they are using on plants.

Johnny’s Seeds

Johnny’s Seeds is a popular brand, and I did use some of their seeds last year with good success.

For a more thorough review of these companies, check out my guide: 9 Best Heirloom Companies.

What Questions Do You Have About When to Start Seeds Indoors?

The process of starting seeds can seem so ominous. I’ve asked hundreds of questions myself and have met with different people to learn about their growing process. There’s always more to learn.

If you have more questions, please drop them in the comments below! I’d love to try to answer them for you! If I don’t know the answer, I will do my best to track it down for you 🙂

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