Basic Seed-Starting Questions Answered:

When to Start Seeds Indoors, What to do If It’s A Little Late for Seed-starting, When To Plant Outside, and More

Part One of this series gave you the how of how to start seeds at home in a small space. Along the way, you’re sure to have questions. Questions like…

…When to start garden seeds? Can you start seeds if it’s later than the recommended start-by date? When should you plan to plant your vegetable plants outside? And, Where can you find dates and information specific to your location?

You have questions; we have answers, and tips for finding location-specific resources, too.  In this post we’ve tried to fill in the blanks and anticipate the questions you might have, and also share some tips and tidbits worth knowing. Should you find yourself with more questions in the end, please use the comments section to let us hear about them!

Seed-Starting Questions and Answers

When Should I Start My Garden Seeds?

Knowing when to start your vegetable or flower seeds is important. You don’t want to start them too early or you’ll have root-bound plants that become too large for their pots; too late and you won’t have enough time left in your growing season to enjoy your harvest. So, when is the right time for seed starting?

The garden growing season in the US and North America does vary, obviously, by geographical location. In other words, gardening starts earlier in the more southern regions and is successively later as you move northward.

Small space seed starting

Start Seeds 6 to 8 Weeks Ahead of Planting

Generally speaking, you should start most garden seeds six to eight weeks before the date that you plan to plant them outside in your garden (or patio containers in the case of more urban gardening situations).

There are some exceptions to this “rule,” a few of which are discussed in subsequent questions (and some ways to overcome them), but in general your most common garden vegetables, and even most flowers, will yield for you if started inside within this time frame.

How Do I Know When to Plant my Plants Outside?

Every location or gardening zone has an accepted date that is considered “the” planting date to start planting plants outside, based on frosts and temperatures. To make life easy, beginning gardeners should focus on this date as their planting date.

This general planting date is what is called your “last frost date.” This is the date that it is generally considered “safe” to plant annual plants and vegetables outside. After that date, your area is not expected to have a frost again until the fall and the change of seasons, so those plants you transplant out into your garden space should be fine with the temperatures for the remainder of the growing season. For example, in Massachusetts, the long-standing rule of thumb is to use Memorial Day as the start of the outside planting season.

To find your last frost date, you can search for the last frost date for your location. Resources such as the Farmer’s Almanac Last Frost Date Interactive Map are very helpful. You can find that here:

Each state’s state university system also has an “extension service,” and these services are excellent resources for both commercial and home growers, specifically tailored to your region.

What If It’s Past the Six-Week before Frost Date?

Many people who will be planting gardens and who are starting seeds this year didn’t actually plan to do so until life was rather flipped on its head. So, there are lots of us out there scrambling now to start seeds for a previously unanticipated garden. And so, maybe it’s already inside your six- to eight-week seed-starting window. Does that mean you cannot start your seeds?

It actually does not mean that at all. The advice to plant out just after the last frost date is advice given to maximize garden production time and, moreover, to protect tender vegetables and flowers from the dangers of frost and freezing temperatures. The timeline of six to eight weeks is what is needed to get the plants large enough and strong enough to tolerate transplant shock and outdoor conditions. But that doesn’t mean that you can’t still start seeds and grow your own food if you are a week or two past that date, potentially even as much as a four week difference (and longer in warmer regions).

start seeds in small space

While six to eight weeks ahead may be ideal, you can still start your seeds. You may just need to plant them outside a couple of weeks later than your area’s first planting date. As long as you have plenty of growing season left after you plant those plants outside, you will still get a very productive, viable crop. All your mainstream garden vegetables will have more than enough time to grow and produce in abundance even if planted a little late.

If you have questions about a specific variety, plant, or crop, again, refer to your seed packet. All the important growing information can be found there, including time to harvest. Look at the number of days you need before your crop is ready to harvest. If you’ll have at least that much time left in your growing season when your plants will be ready, you have enough time left to start your own garden seeds.

Your harvest might begin a couple of weeks later, but there is certainly nothing “wrong” with that. For our own personal reasons of time and availability, there will be lots of us planting later than the start date, anyway. Don’t let a week or two dissuade you from growing your own, fresher, cheaper, better, vegetables and flowers!!

Are There Plants That Get Planted Before the Last Frost Date?

The short answer is “yes.” But you also don’t have to. Whatever does that mean?

There are a number of cold-hardy vegetables and plants that have their own personal planting date. Peas, for example, prefer growing in colder weather. And so ideally, peas would be started even earlier than when you would plant out a warm-weather-only crop like tomatoes or peppers. Depending on your winter or spring, this might be as early as six weeks earlier.

In general, this early planting doesn’t apply to flowers and herbs almost at all, with so few exceptions it’s probably not worth the focus in this conversation. However, cole crops —broccoli, cabbages, cauliflower, kale, lettuce, spinach, Brussels sprouts—are all plants that can, if well-started, well-established, and properly hardened off, be planted outside before the last frost date.

You do, however, want to consult your seed packet for tolerable temperatures. These plants can take some cold, but do have a lower limit to their ability. Turnips and radishes are also considered cole crops that can be planted before your last frost date, but these seeds should be sown directly in the ground and not started inside in pots.

Now, just because these crops can be planted outside earlier than the last frost date, that doesn’t mean you have to. If you’re not ready to start gardening early, or if you just prefer to start everything at one time, you can certainly choose to do that, too.  

Are There Plants that Need More Than 6 to 8 Weeks to Grow Before Planting?

Yes. There most definitely are some plants and seeds that require a very long indoor start and growing season and which, even with a later planting date, really can’t be done with a late start.  

These are plants that require starting from seed more like 12- to 16-weeks ahead or you will simply not have enough time to grow them to harvest regardless. Some typical vegetables and seeds in this category include onions from seed, celery, some flowers, and a number of herbs.

However, this doesn’t mean that you can’t grow them as part of your garden for this year—you just need an alternative that can grow within your growing season. Here are a few examples of common garden vegetables that you might not be able to grow from seed, but that you can still start in your garden in the spring at planting time, along with the alternative options for starting them:

  • Onion starts or sets (grow from small baby onion bulbs, called “sets”)
  • Seed potatoes—seed potatoes are not literally seeds, they are potatoes with sprouting eyes from which new plants will grow
  • Sweet potato slips—typically you will have to purchase these slips from a garden center or order them online
  • Purchased, started plants—In the later stages of the seed-starting season, things like celery, celeriac, and many herb plants are better if purchased from a garden center or from a greenhouse that started them in the winter months. (which is perhaps not as cheap or as gratifying as growing from the seed up, but which is still an economical option as compared to grocery store produce that helps you fill in the blanks for this year—and maybe next year, with this year and experience under your belt, you can plan ahead and expand your seedling repertoire!)

All of these starts are available at most commercial greenhouses, garden stores and/or through online ordering from seed and garden companies.

What Are Garden Zones and What Do Growing Zones Mean to Me?

Gardening zones, or more accurately plant hardiness zones,refers to a geographical climate-based zoning system developed by the United States Department of Agriculture (USDA) as a climate and planting guide for locations throughout the country. Many countries have since used this system to develop their own location-specific guides for planting and plant hardiness. The zones are numbered 1 through 13.

It is very easy to find your hardiness zone, and once you have it you can use it to reference seed and planting information for your specific location. An interactive map is available online at the USDA website. Just click on your location to find your zone. Knowing your garden zone will help you plan planting dates, learn about season length, and also choose plants that are capable of growing to harvest in your location.

What Types of Seeds Can I Start in a Six to Eight-Week Window?

With few exceptions, most of your more common and more commonly-used vegetables, and many flowers, can be started and grown to transplant age within 6 to 8 weeks. Broccoli, cauliflower, tomatoes, peppers, cabbage, certainly any greens like lettuce or spinach, all make the list, as well as many others.

Flowers will do better if started earlier than 8 weeks and may be a bit on the small side if started in 6 to 8 weeks, but in this timeframe you can get most flowers at least large enough to plant outside, where they will catch up and have time to come into flower, if a bit delayed. Some flowers will even do well if direct-seeded outside when the weather warms above freezing (cosmos and zinnias are nice cut flowers that do well as direct-seeded plants or when pre-started inside). And still others prefer NOT to be started inside at all (see below for more on that topic).

Some herbs can also be fit into this 6 to 8-week window, though they’ll do better on the longer end of the spectrum. Basil can pretty reliably be grown to transplant stage within 8 weeks, as can sage, chives, parsley, cilantro, and dill (though dill is a good candidate for direct-sowing, too).

Are There Plants That Should Wait and Start Closer to a 4 to 6 Week Pre-frost Period?

Some types of plants don’t actually do all that well in pots and/or with transplanting and for that reason, they actually will do better if they are started later and live less time in pots. These are primarily plants that do not do well with potting up, and so for these plants it is best to start them in degradable organic pots (like peat pots) that can be planted directly in the ground.

Start squash and cucumbers in individual peat pots

Do not plan to “pot up” these seedlings at any stage and try not to disturb their lives more than necessary. Also, try to limit the time they do spend in the potted stage, and so plan to plant them about 4 weeks before you want to plant them outside. This gives them enough time to grow to transplant size and develop enough roots without outgrowing their pots and therefore not requiring potting up. You’ll still get the jumpstart on the season needed for earlier vegetables, but the plants do not deteriorate from too much time being potted.

That said, these are also often the seeds that will do well if directly sown in the ground, so that, too, is an option and you may choose to forego starting them inside altogether. They tend to be larger seeds and plants so it’s less of a worry that you will accidentally weed them out when they are young and they can compete well with whatever weed seeds they do encounter as young seedlings.

The plants to hold off on and start around the one-month-before-last-frost date are:

  • Cucumbers
  • Squash of any variety
  • Melons
  • Pumpkins

Are There Plants I Should Not Start Inside?

Definitely. For various reasons, and chief among them the fact that they just do not do that well germinating in pots and then being disturbed and potted up, it is recommended to “direct sow” some kinds of seeds. These include:

  • Carrots
  • Radishes
  • Beans
  • Peas
  • Sunflowers (sunflowers truly do not do very well when started and then transplanted; the time lost due to transplant issues ends up being little to no advantage over direct-sowing seed)
  • Beets
  • Other root vegetables like parsnips, turnips

Some seeds and plants can either be direct-sown or started inside, as discussed above. Examples include lettuces, spinach, cucumbers, squash, and melons.

How Much Space Do I need to Start My Own Seeds?

Not much. With a good seed-starting method, you really only need a couple of square feet of space to get your seeds started. When you split these germinated seeds into individual pots or cell packs, you’ll need a little more room, but even then you can achieve a great garden’s worth of transplants in the footprint of just a couple square feet if you “go up”—in other words, use plant shelves rather than trying to space everything out over a single surface.

Start up to 96 garden plants in just 2 square feet of space!
Two 10×20 inch plant trays will fit 96 plants in 6-cell packs, in just 2 sq ft of space! 4-cell packs, as shown here, will grow 64 plants in 2 sq ft!

For example, in two-square feet of space you can fit two 10 x 20-inch seed trays. Each tray will fit 8 cell packs, and you can use either 4 packs or 6 packs when it comes time to pot up individual plants. That means that each tray can fit either 32 or 48 individual plants. So in just one two-foot space you can grow as many as 96 plants for your garden!  In this way and with the method laid out in this series of posts, it truly does not take much space at all to start plants from seed for either an urban or a country garden—no greenhouse required!

The other posts in this series will help you find the space you need for small-space seed starting. Start with Post One of the series and subscribe or continue on through the different stages as you go from seed to transplant time.

Small-Space Seed Starting Part 1: How to Grow All Your Garden Plants at Home with Limited Space and Light

*This post is Part 1 of a series that will take you from the very beginnings of starting seeds in a small space, such as a home, apartment, or backyard greenhouse, all the way through to getting your young plants ready to plant outside. Start here today for seed-starting success, subscribe, and come back over the next week or two as we learn what to do at each phase of the growing process.

For so many good reasons, this virus is seeing droves of people turning to home gardening. Lingering concerns over supply, transportation and warehousing breakdown, availability, food security and safe handling, and questions of future cost and affordability are all real reasons people are looking toward being more self-sufficient. The demand for garden seed is proof positive that more people are planning to grow at least some of their own this year.

If you are wondering how you can start seeds to grow your own food in the space that you have, you’re in the right place!

Whatever your space, large or small, this seed-starting method is ideal for successful home gardening and healthy plant starts!

Here, we learn how to start seeds for the home garden with very little space required!

It’s a Very Good Time for Seed Starting

If there is one fortunate thing about all of this, it is that the time is just right for starting your seeds and planning your garden in most locations in the northern hemisphere. And you do not need a large sunroom, greenhouse, or other big space in order to do so. Even in an apartment, if you can spare a dedicated corner, table, or shelf, you can grow your own vegetables, plants, and flowers from seed and have more than enough to fill your patio or even a large garden. In fact, you’ll be amazed at just how successfully you can grow more than enough in a very limited growing area. Here’s how:

Gather Your Seed-Starting Supplies

For this small-space seed-starting method, you will need a few basic supplies:

  • Seed starting mix
  • Four-inch pots
  • Seeds
  • Plant labels
  • 1020 plant tray (solid no holes)
  • 1020 plant flat (webbed, “daisy flat”)

Seed Starting Mix. Get a bag of seed starting mix, which is a little different than potting soil. You will not need a very large bag and a small 12-quart bag of inexpensive seedling mix is enough for most home gardeners (depending, of course, on how many seeds you’ll be starting).

Seed starting mix does not contain added fertilizer and is lighter and less dense than regular potting mix. It is also free of large chips and chunks, which are problematic for tiny seeds just getting started. Seedling mix allows seeds of all sizes to germinate and push their way to air and light without being hindered and dying off before they can break through.

Seed starting mix is highly recommended for plant germination but if you really cannot access seed starting mix and must use regular potting soil, sift it through a colander to remove large pieces, sticks, and chunks or chips of wood.

four inch pots for starting seeds

Seed starting containers. At this stage all you need is something about four inches square that you can use to start each type of seed in. Four-inch square pressed peat or “cow pots” are ideal, however you can even use the segmented plastic cell-pack seedling pots, or even some disposable Tupperware or clean plastic takeout containers (if using recycled containers, make sure to punch drain holes in the bottom for watering and drainage). You will need one container per seed variety or seed type. See the pictures below for an idea of what will work.

Seeds. Gather all the seeds for the different vegetables or flowers that you plan to plant.

Plant labels. You will need something to label your pots. Plastic plant labels that can be written on with a permanent marker work best. Craft sticks or popsicle sticks may be used, too, but often wooden sticks end up blurring and can become unreadable when water is soaked into the stick.

1020 solid flat tray for planting seeds at home

Large flat for watering. This can actually be a plant tray with no holes (such as the long, approximately rectangular 10 x 20 black plastic flats often called 1020 flats) or even a low, long, rectangular Tupperware or plastic storage container will do. Even a 9 x 13 baking pan would do the trick.

Daisy Tray for seed starting. 1010 plant tray

Plant tray or container for holding started containers. Again, a 1020 webbed plant tray, or “Daisy Tray,” is ideal, but if you have some recycled low tray with edges that you are willing to dedicate to plants and dirt, that’s just fine, too.

Step by Step Seed Starting for Small Spaces:

The method I prefer, which was taught to me by the greenhouse manager and head of a local garden store, is what follows here.

This method of seed starting has us starting many seeds in one small vessel rather than in individual pots or cells. (There are a few exceptions to this rule that we will discuss in a later question and answer post). We do this to germinate a lot of seeds in a small space in short time. It does require a second step later on, called “potting up.”

The result is healthy, vigorous plants ready for transplanting out to your beds, patio pots, or garden with very limited loss. This method also lets you start a whole garden’s worth of seeds in just an hour or two and in just about two square feet of space, which could prove very important right now if you are a bit behind getting your seeds started for your new garden.

Each type of seed will be started in one 4 x 4-inch pot. We then water and place them in a good place for germination until ready for the next step.

Step 1. Moisten the seed-starting medium.

Lightly moisten the seed starting mix and mix it through a bit so that the soil is evenly moist.

The seedling soil should not be dripping wet or so wet that it clumps. It should be workable and able to be sprinkled with your fingers. You will water the potted seeds again at the end, but this will work to sort of “prime” the mix so that it can wick up adequate moisture at the end.

seedline soil to start seeds at home

Step 2. Fill starter post with seedling soil.

Fill one roughly 4 x 4-inch pot or cell pack with seed starting mix. Fill to about 2/3 full.

Plant seeds at home

Step 3. Make rows or a base for the seeds.

If you are using a pot that is not divided, make small “rows” in the soil using a pencil, popsicle stick, or your finger.

If you are using divided cell packs, fill them no more than 2/3 full and do not make rows.

For most seeds, you are aiming for a row or seed depth between ¼ and ½ inch. Your seed packet will tell you the depth to plant the seed if you are unsure (look for “Planting Depth” listed on the package. If none is listed, plant at a depth of ½ inch).

If in doubt, it is better to plant at a shallower depth rather than one that is too deep and ¼ to ½ inch will work well for most seeds. The reason that this is less important is because you will only be sprouting the seeds in these bulk pots. They will be transplanted “up” later.

Seeds in a row small space seed starting

Step 4. Plant the seeds.

Sprinkle the seeds along the length of the short rows (in non-divided bulk pots) or evenly over the surface of the soil area in the cell packs.

You do not need to worry about proper seed spacing like you would if you were planting out in a bed, permanent pot, or garden. Try not to overcrowd the seeds; leave a little space between. Also aim for a single seed layer and try not to plant so heavily that you end up with seed on top of seed. Again, the seedlings will be transplanted at a later date, so “proper” seed spacing is not necessary.

Cover seeds with soil and tamp down.

Step 5. Cover the seeds.

Lightly cover the seeds with soil to a depth of ¼ to ½ inch by sprinkling more seed-starting soil on top. Gently pat the soil down with your fingers. Be sure to label your pot!

bottom water seeds to germinate

Step 6. Water the seed pots.

Water the pot from the bottom up. To do this, fill a solid plant tray or large, flat, approximately 2-inch deep plastic container with lukewarm water. Place the seed pot into the tray of water.

Soak seed pots for better seed starting.

The soil will draw water from the bottom. Leave the pot in the water just until the top of the soil has completely and evenly darkened, indicating it is evenly and adequately moist.

Remove the pot when the soil is evenly dark. Avoid overwatering.

8 four-inch pots fit in one germination tray.

Step 7. Place labeled pots in a germination tray.

Once planted and watered, place the pot in a tray for germinating. All of your different pots and varieties can go together into this tray (or trays if you need a couple).

You can fit approximately 8, 4 x 4 pots or cell packs in one standard plant flat or tray. That’s 8 different seed varieties in just one standard plant tray!

The basket-like webbed “daisy” trays are ideal, because when it comes time to water your pots later on you can place the entire tray into a solid 10 x 20 black germination tray and quickly and easily bottom-water the pots all at once. (That said, use whatever you have on hand if you need or want to!)

Step 8. Place in a moderately warm, dark space to germinate.

If you think along the lines of mimicking Mother Nature, climate control will come easily to you. Just think about the conditions that your seeds would naturally and ideally prefer if they were to grow outside in their natural habitat. A temperature range of 65-75 is a comfortable level for almost all seeds and at this steady temperature your seed should germinate quickly. This is normal room temperature in most homes, so a comfortable, draft-free corner of your home is a good place for your seeds to be while they work to germinate.

Another natural condition for germinating seeds is darkness…think about a cozy seed tucked into a nice, dark, soil. One way to mimic these conditions is to choose or create a dark space in which to place your germinating seeds. At this point, light is not your goal.

Step 9. Maintain moist soil.

The best thing for you to do for your germinating seeds now, once placed in a warm, dark space, is to leave them alone. Almost.

Your seeds and their soil do need to stay moist, but not wet. It is usually best in the home setting to cover the tray full of seed pots with a covering that will help retain moisture. If it also helps block light, that is even better. A length of plastic wrap, aluminum foil, a large box, or a second solid plant tray placed upside-down over the tray all work well.

Peek in on the seeds once every day or two just to make sure the soil has not dried out. If it is getting too dry, place it in a tray of water again, just until the soil darkens. Do not overwater so that you do not rot the seed. You might also choose to lightly mist or spray the pot with a household spray bottle (a new one that has not held cleaning agents or chemicals!).

Seedlings that have been potted up.

Step 10. Patiently wait to pot up!

This is all you are going to do with your seeds for about a week or two. The fastest-germinating seeds, often things like broccoli, cauliflower, cabbages, and similar plants, will pop up first and under good conditions this is usually within 7-10 days. Other seeds, tomatoes, peppers, and eggplant, for example, take longer. You seed packet will estimate germination time so you have an idea of what to expect, but do know there is always a range.

Plan to “Pot Up”

In about two weeks you will have seeds that have germinated and grown early roots. You will need to “pot up” these young seedlings into individual growing vessels until they are ready to be planted outside in their permanent garden (or patio container garden) home.

This interim time is the time when you should plan and purchase any supplies and materials that you do not already have for the next stage of small-space garden plant growing. This will probably include a grow light setup that can be tucked in a small space of your home and provide the light your new seedlings will need as they get growing. 

You have a window of about two to three weeks before you need to move on to the next phase, so if you start preparing when your seeds are just tucked away for germinating, you should have plenty of time to order or gather the supplies you need.

Subscribe or check back here for the next post in this series, which will give you important tips, tricks, and information to move on through seed-starting success!