When to Start Your Seeds Indoors | Gardener's Supply (2024)

More Articles

Find more garden information

Other Article Categories

Advice Seed Starting When to Start Your Seeds

Learn how to create a seedstarting schedule

By Kathy LaLiberte

When to Start Your Seeds Indoors | Gardener's Supply (1)Seedlings in a seed-starting tray. Photo: Carrie Bettencourt

Years ago, I was diligent about keeping a gardening journal. I didn't make daily entries like Thomas Jefferson and other famous journal keepers, but on a weekly basis I would record the major tasks I'd accomplished, a general weather summary (hot, dry, wet, cold), what plants were in bloom, and what crops were coming in. As my life became more and more crowded, those entries trailed off. It's a shame, because I really miss being able to peruse journal entries from years past. I would like to be able to remember when I picked my first tomato, or whether the lilacs bloomed early or late. But all those rich and wonderful details of prior gardening seasons are now lost.

One piece of record-keeping that I have managed to maintain are my annual seed starting calendars. I do know which week I planted my pepper seeds last winter, and the date I sowed the alyssum. And I know whether I started my onion seeds earlier or later than the year before. Because I start over 40 types of plants from seed (and about 70 different varieties), my seedstarting schedule is essential.

You'll find my own schedule below for reference, sorted by "start" week before last frost date. But this is not necessarily the exact schedule I'd recommend for you. I garden at the cold edge of zone 4. My grow lights are in a cool upstairs bedroom where seedlings grow quite slowly. But once it's April, all the seedlings go out into my warm and sunny greenhouse where they grow very rapidly. Each year, I consult my records and make a few adjustments to my schedule. My goal is to produce seedlings that are mature—but not overgrown—when it's time to go into the garden.

When to start
(before your last frost date)
What to start
11 weeksheliotrope, candytuft, primula, leek, viola, snapdragon, early greens (to be planted out in the cold frame or greenhouse beds)
10 weeksdelphinium, matricaria, onion, parsley, Greek oregano, impatiens, rudbeckia, early broccoli
9 weekspepper, coleus, shallot, eggplant, cherry tomato
8 weekstomato, alyssum, cleome, salvia horminum
7 weeksageratum, zinnia, more lettuce, radicchio
6 weeksbachelor's buttons, agastache, aster, basil, marigold, sweet pea, calendula
5 weekssanvitalia, cabbage, convolvulus, nicotiana, lavatera, nigella, phlox, phacelia
4 weeksmorning glory, nasturtium, melon, cucumber, squash

Your own seed starting conditions are probably quite different from mine, and your planting schedule should be adjusted accordingly. Asking a garden-savvy neighbor when they sow their seeds is one easy way to get started. But if you want to figure out your own planting schedule from scratch, here's how to do it:

Buy Organic Seeds

When to Start Your Seeds Indoors | Gardener's Supply (2)

Seed packets, sorted by planting date.

Sort your Seed Packets

Start by separating all your packets of seed into two piles: those that will be "direct-sown" (planted right in the garden) and those that will be started indoors. The outdoors pile will include most vegetables, such as peas, beans, corn, radishes, carrots, beets, lettuce, spinach, melons, cucumbers, and squash. Put a rubber band around whatever seeds you'll be planting outdoors and set them aside.

Most annual flowers will also go into the direct-sow pile: zinnias, asters, lavatera, nasturtiums, sunflowers, bachelor's buttons, nigella and calendula. If your growing season is very short or your garden conditions are especially difficult, you may decide to put some of these annual flowers into your "sow indoors" pile. Most perennial flowers will need to be started indoors.

Now spread out your "sow indoors" pile and start reading the back of the seed packets. Unfortunately, you'll probably find that planting instructions are pretty vague. Home gardeners would have a much easier time if seed companies would provide us with the information we need. At the very least, you should find something like, "For earliest bloom or fruit production, start 6 to 8 weeks before last frost date."

Sort your packets into piles according to these recommendations, making separate piles for 5, 7, 9 weeks, and so on. Some packets, especially those for perennials, may only tell you how long it takes the seeds to germinate. If that's all you have to go on, take that figure (which is usually a range) and add 6 weeks. Then put the packet into the appropriate pile.

If there's no information on the seed packet, you can pretty safely just start all your seeds about 6 weeks before you'll plant them outdoors. Make note of which plants are too big or too small at planting time, and then you can make adjustments next year based on your notes. For detailed instructions on starting 500 varieties of annual and perennial flowers, I highly recommend Eileen Powell's book, From Seed to Bloom (Storey 1995).

Creating the Calendar

Start by finding the average last frost date in your area. You can get frost dates online by entering your zip code. To calculate your planting dates, you need to count back from last frost date in one-week increments. (I base my calendar on Saturdays, because that's the day that I usually have available for seedstarting). In my area, the last frost date is May 15. For me, when I count back from May 15, Week 4 is April 15, Week 11 is the week of February 26, etc. Simply write the week number (8,4, 6 or whatever) on each seed packet and use a rubber band to keep each pile together. When the planting week arrives, you just grab the right packet and start planting.

Making Adjustments

Now that you have a great schedule, here are a couple reasons you may want to make some adjustments:

Start earlier: Seeds take longer to germinate and plants grow more slowly when air and soil temperatures are cool (below 70 degrees F). If you plan to start your seeds in a cool basem*nt or cool bedroom, you may want to shift your whole schedule a week or two earlier.

You can see on my schedule that I start some greens and broccoli at the end of February. That's because these seedlings get planted outside about a month before the last frost date. If you have a cold frame or greenhouse, — or if you use other season-extending techniques, such as row covers or pop-up covers — you can plant tender seedlings several weeks before the last frost date. Just count back from that expected planting date to get the right date to sow your seeds.

When to Start Your Seeds Indoors | Gardener's Supply (3)A pop-up-style cover protects transplants from spring chills.

Start later: If you grow your seedlings in a greenhouse or an especially warm room (more than 70 degrees F.), you should cut a week or more out of your schedule. Heat promotes rapid growth, and you could find yourself with giant plants that are ready for the garden before warm weather arrives.

I hope you find this information helpful rather than intimidating. I find making up a schedule ahead of time makes it easy to figure out what I should be planting each week. When you start transplanting into the garden, write a few notes on your schedule so you can make adjustments next season. Remember that every year will be a little different and you'll never get it exactly right. But for me, that unpredictability is part of what makes gardening fun.

Everything you need to start seeds

Related articles

  • Seed-starting 101
  • Grow Annuals from Seed
  • Perennials You Can Start from Seed

Last updated: 12/08/2022

Related items

GrowEase 12 Replacement Reservoirs, Set of 3

$8.99

GrowEase 12 Replacement Platforms, Set of 2

$4.99

GrowEase 24 Replacement Planting Trays, Set of 3

$12.99

GrowEase 12 Replacement Planting Trays, Set of 3

$8.99

GrowEase 24 Replacement Domes, Set of 2

$7.99

GrowEase 24 Replacement Platforms, Set of 2

$9.99

GrowEase 12 Replacement Capillary Mats, Set of 3

$3.99

GrowEase 24 Replacement Capillary Mats, Set of 3

$6.99

GrowEase 24 Replacement Reservoirs, Set of 3

$10.99

Organic GrowEase Seed Starting Success Kit

$39.99

GrowEase Seed Starter Kit

$11.99 - $17.99

  • Easy Seeds for Beginners

  • Heirloom Varieties to Grow

  • How to Prevent Damping Off

Get the Dirt

Stay up to date on new articles and advice. Please fill out the information below.

  • Easy Seeds for Beginners

  • Heirloom Varieties to Grow

  • How to Prevent Damping Off

When to Start Your Seeds Indoors | Gardener's Supply (2024)

FAQs

When to Start Your Seeds Indoors | Gardener's Supply? ›

Most seed packets suggest a planting time, such as "sow seeds indoors six weeks before your average last frost date." To calculate your planting date, start by determining your average last spring frost date, mark it on a calendar, and count back in one-week increments.

When should you start plants from seeds indoors? ›

It's very rewarding to watch tiny seedlings blossom into healthy mature plants. Planting seeds is also a great way to grow specific varieties. March is a great time to start seedlings indoors. Generally, start planting seeds indoors 6-10 weeks before the last frost date.

When should I start seeds list? ›

Vegetable and Herb Seed-Starting Timetable
  1. Sixteen Weeks: Rosemary, Roselles and Strawberries (for first year crop)
  2. Twelve Weeks: Brussels Sprouts, Cardoons, Celeriac, Celery, Cutting Celery, Parsley Root and Stevia.
  3. Eleven Weeks: Artichokes, Cauliflower and Leeks (transplant out four weeks before the last frost date).

What are the 3 conditions necessary for germination? ›

All seeds need water, oxygen, and proper temperature in order to germinate. Some seeds require proper light also. Some germinate better in full light while others require darkness to germinate.

How many seeds per hole when starting seeds indoors? ›

Most seeds prefer a depth of about 2 times their length. The tiniest seeds can be sprinkled directly on the surface. Cover the seeds with a thin layer of soil. Plant about 3 seeds per hole (more if using older seeds) and once they germinate, thin down to leave only the strongest seedling.

Is February too early to start seeds indoors? ›

Even if the last thing you're thinking about in January or February is the garden, it's actually a great time to start seeds indoors for frost-hardy leafy greens and for slow-to-get-started herbs.

Is January too early to start seeds indoors? ›

First there is too little light at this time of year – If you rely on a sunny windowsill to start your seeds, you want to wait a little longer to start seed sowing. Most plants need at least 10 hours of light in order to grow well, and in January, much of the Northern Hemisphere receives less than that.

What month is best to start seeds indoors? ›

Mid-March is the best time to start many vegetables and annual flowers indoors for transplanting outside once the threat of frost has passed.

Can you start seeds too early? ›

Rootbound seedlings

Planted too early in the year, seedlings can outgrow their pots before it's time to transplant them outside. This leads to rootbound seedlings—when roots become so tightly confined in a container that growth is stunted.

What month do you germinate seeds? ›

Those who live in hot climates—Zones 8 or 9, for example—may be able start seeds as early as December. Northern gardeners, like those who grow in Zones 3 or 4, should wait until March or April to start most seeds, depending on the plant's germination period. Don't fret if you have to wait a little longer.

What stimulates seed germination? ›

Bioactive gibberellins (GAs) promote seed germination in a number of plant species. In dicots, such as tomato and Arabidopsis, de novo GA biosynthesis after seed imbibition is essential for germination. Light is a crucial environmental cue determining seed germination in some species.

What are the 4 critical factors for seed germination? ›

Temperature, moisture, air, and light conditions must be correct for seeds to germinate.

What promotes seed germination? ›

Germination is induced most commonly through the imbibition of water at a species-specific temperature. Imbibition of dry seeds activates a series of events (Bewley, 1997) including oxidation, degradation, and mobilization of accumulated reserve components (Penfield et al., 2005a).

Does 1 seed equal 1 plant? ›

In general, two to three seeds should be planted per hole. Seeds do not have 100% germination rates, so not every seed planted will sprout. Overseeding holes, cells, or pots will help ensure that the number of plants you desire will grow (or more. Don't exceed three seeds per hole.

How long can seedlings stay in egg cartons? ›

But you also can't leave your seedlings in their egg cartons for too long, waiting for the weather to heat up. Seedlings should be moved to the garden once the roots reach the bottom of the tray, but before they start to grow into a circle.

Can I start seeds in January? ›

Look through your catalogs and find the vegetable seeds for your garden. Some flower varieties should be started in January. In a warmer environment you can plant certain vegetables, but must be ready for a frost. Indoor herbs are always great to grow in a sunny windowsill.

Should you soak seeds before planting indoors? ›

By soaking the seed, it enables the new growth from the inside to push through the hard shell and grow. The seeds that could benefit from a good soaking include: corn, pumpkin, beans, chard, beets, and peas. The seeds you shouldn't soak include: carrots, lettuce, radish, celery, turnips, and spinach.

How long to grow seeds indoors before transplanting? ›

Starting transplants too early or too late can result in weak plants or late harvests. See our edibles infographics and the UF/IFAS Florida Vegetable Gardening Guide for planting dates specific to your regions of Florida. Aim to start seeds indoors 4-8 weeks before the suggested outdoor planting dates.

References

Top Articles
Latest Posts
Article information

Author: Rob Wisoky

Last Updated:

Views: 5664

Rating: 4.8 / 5 (68 voted)

Reviews: 83% of readers found this page helpful

Author information

Name: Rob Wisoky

Birthday: 1994-09-30

Address: 5789 Michel Vista, West Domenic, OR 80464-9452

Phone: +97313824072371

Job: Education Orchestrator

Hobby: Lockpicking, Crocheting, Baton twirling, Video gaming, Jogging, Whittling, Model building

Introduction: My name is Rob Wisoky, I am a smiling, helpful, encouraging, zealous, energetic, faithful, fantastic person who loves writing and wants to share my knowledge and understanding with you.