By: Liz Baessler
Gardening in zone 3 is tricky. The average last frost date is between May 1 and May 31, and the average first frost date is between September 1 and September 15. These are averages, however, and there’s a very good chance that your growing season will turn out to be even shorter. Keep reading to learn more about how and when to start seeds in zone 3.
Starting seeds in zone 3 indoors is sometimes the only way to get a plant to reach maturity in the cold, short growing season of this region. If you look at the back of most seed packets, you’ll see a recommended number of weeks before the average last frost date to start the seeds indoors.
These seeds can more or less be grouped into three groups: cold-hardy, hot weather, and fast-growing hot weather.
Seedling planting times for zone 3 depend upon both frost dates and the type of plant. The reason zone 3 seed starting dates are so early for cold-hardy plants is that the seedlings can be transplanted outdoors well before the last frost date.
These plants can usually be moved outdoors anytime between April 15 and June 1. Just make sure to harden them off gradually, or they may not survive the cold nights. Seedlings from the second and third groups should be transplanted after all chance of frost has passed, ideally after June 1.
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Two of the most important aspects of gardening are knowing when to plant and what to plant in your vegetable or flower garden. However, it can be difficult to know the exact time to begin planting in order for a garden to fully flourish throughout the growing season. If your plant or garden fails to thrive, simply adjusting your planting time frame might make a big difference. A planting calendar takes the guesswork out of the process.
The Gilmour planting guide is an ultimate guide on when to plant what, based on planting zones and frost dates. Read on to learn more about:
Starting garden plants from seeds indoors can be an enjoyable project for any gardener. It's a relatively inexpensive way to grow a wide variety of plants. Many garden favorites are found in a greater variety of colors, sizes and growth habits as seeds, rather than as started plants.
Seeds are available from many sources, ranging from your local building supply store to garden centers and mail order catalogs. Their prices can vary greatly. The newest hybrids command higher prices, as do seeds of rare or unusual plants, as well as certified organic seed.
Planting and care information is often more complete on name-brand seed packets. If name brand and "off brand" seed varieties are the same for a given flower or vegetable, there shouldn't be any difference in the plants' ultimate quality. The percentage of germination and seed purity is governed by law.
A windowsill is not a good location for starting seeds. Window sills can be the coldest place in the house, especially at night, and then the hottest during the day.
Sunlight in Minnesota gains strength through April and May. But sunlight through a window is relatively weak compared to artificial light sources kept close to the plants. There are also many cloudy days of very low light levels during a Minnesota spring.
If you're starting only a few plants and have roomy window sills, a south-facing window may be all the growing space you need.
Start seeds in small, individual containers. It's best to use divided containers with a single seedling per container, rather than filling a larger container with potting mix and sowing many seeds, because the seedlings' roots will grow into each other and are likely to be injured later during transplanting.
There are many kinds of fiber pots made from organic materials such as peat, cow manure, and shredded wood. Some gardeners make pots from strips of newspaper. Fiber or paper pots that break down in the soil are particularly good for raising seedlings that don't transplant well, such as cucumbers and squash.
Clear plastic domes that fit over trays of plants allow light in, but help keep moisture from escaping. They can also help retain heat provided to the root zone. The domes should be removed when the seedlings are tall enough to touch them.
Exceptions to using individual containers are onions and leeks from seed. These can be started in one larger flat and transplanted out into the garden while still small without harm to the seedlings.
Soilless seed starting mixtures
Commercial seed-starting mixes, usually composed of vermiculite and peat, without any true soil, are recommended for starting seeds. They're sterile, lightweight and free from weed seeds, with a texture and porosity especially suited to the needs of germinating seeds and tiny seedlings.
Set the cell flats or containers into a solid tray, fill them with potting mix, and water the mix before sowing seeds. The potting mix will settle down into the containers. Add more potting mix and water again, until the containers or cells are nearly full.
|Month||How long to keep indoors||Plant|
|Mid-January||16-17 weeks||Flowers: lisianthus|
|Early February||14-15 weeks||Flowers: geraniums, pansies/violas, wax begonias Vegetables: leeks, onions|
|Mid-February||12-13 weeks||Flowers: browallia, clarkia*, dusty miller, fountain grass, impatiens, larkspur, lobelia, nemesia*, stocks, torenia Vegetables: celery|
|Early March||10-11 weeks||Flowers: ageratum, coleus, dahlia, gazania, heliotrope, lavatera*, petunias, rudbeckia (black-eyed Susan), scabiosia, schizanthus, snapdragons, verbena, vinca/periwinkle Vegetables: broccoli, Brussels sprouts, cabbage, cauliflower, head lettuce|
|Mid-March||9 weeks||Flowers: bells of Ireland, candytuft, cleome, dianthus/pinks, hollyhock, marigold (African), melampodium, mimulus, nicotiana, nirembergia, ornamental pepper, annual phlox, salpiglosis, scarlet sage/salvia, statice, strawflower, sweet alyssum, tithomia, trachymene Vegetables: eggplant, okra, peppers|
|Early April||5-6 weeks||Flowers: amaranthus, aster, baby's breath, bachelor buttons, balsam, calendula, celosia, cornflower, four o'clock, marigold (French and gem), morning glory, nasturtium, ornamental basil, ornamental kale, portulaca, strawflower Vegetables: tomatoes|
|Mid-April||3-4 weeks||Flowers: cosmos, sweet peas, thunbergia, zinnia Vegetables: sweet potatoes|
|Early-mid May||1-2 weeks||Harden off all plants|
* Use peat pots or other biodegradable pots as these plants are more sensitive to damage during transplant.
To make a schedule for your garden, just take the Excel spreadsheet and adjust the “Last Spring Frost” column to reflect the week of the last spring frost (orange column or week of May 2 in my schedule) for your location. Next, identify the appropriate first planting (FP) date for each vegetable.
For example, since peas are very cold tolerant, column 3 identifies they can be put out 6 – 8 weeks before the last spring frost. So, in my schedule, peas can be put out the week of March 14 – March 21, six to eight weeks ahead of my week of May 2 last spring frost date.
Once you’ve got your first planting dates, you can establish the dates for starting seedlings indoors (SI) for those vegetables that you intend to transplant. So, using peas again, column 2 says they should be started indoors 3 – 4 weeks before setting out.
Based on that, I backed up three and four weeks and identified that peas should be started indoors the weeks of February 14 or 21 if I want to transplant them into the garden rather than direct sowing (to get the earliest possible peas). For those vegetables that are directly sown outdoors, only the first planting dates need to be established – like the radishes in my schedule.
Now, I like to know approximately when production will start (#) for each vegetable. To do this, find the days-to-maturity number for each variety (should be on the seed packet), divide by seven for weeks, and move forward that many weeks on the schedule to identify when your plants will start producing.
So, using my pea example again, my earliest are identified as 52 days-to-maturity which means about 8 weeks. Counting 8 weeks forward from my February 21 seeding date puts me on April 18 for the first production.
Once you’ve identified when production will start for each vegetable, then indicate about how long it will continue based on the first planting. Using peas again, once the peas start producing, they should continue for a couple of weeks, so I show that by indicating pea production the weeks of April 18 through May 9.
For vegetables that will continue to produce until frost, indicate with “# until frost —>” as shown for chard, beans, etc. For those vegetables that only produce for a limited time, remember that you can often use succession planting to extend the harvest.
Do the above for each vegetable you’re growing and you’ve got a handy schedule for planting your garden, and if you keep notes and tweak it each year, it will only get better.
I’m being quite aggressive on our seed starting and planting schedule based on previous year’s experience and the fact that the USDA has now revised our Zone to 6A.
It pays to get things out to the garden as soon as possible and to really improve production, I’m also starting to use faster-maturing varieties – they can drastically improve when production actually starts.
If you need some free garden seed catalogs to select varieties from, there are links to order them on the Free Garden Seed Catalog Links for 2021 post.
That’s the great thing about taking the time to create a schedule like this it can be adjusted from year-to-year, so you can get better at timing things. I need to get busy organizing supplies soon, it’s almost time to start transplants!
As a founding employee of Gardener's Supply, I wore many different hats over the years. Currently, I have my own company called Johnnie Brook Creative. The gardens around my home in Richmond, VT, include a large vegetable garden, seasonal greenhouse, cutting garden, perennial gardens, rock garden, shade garden, berry plantings, lots of container plants and a meadow garden. There's no place I'd rather be than in the garden.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||What to start|
|11 weeks||heliotrope, candytuft, primula, leek, viola, snapdragon, early greens (to be planted out in the cold frame or greenhouse beds)|
|10 weeks||delphinium, matricaria, onion, parsley, Greek oregano, impatiens, rudbeckia, early broccoli|
|9 weeks||pepper, coleus, shallot, eggplant, cherry tomato|
|8 weeks||tomato, alyssum, cleome, salvia horminum|
|7 weeks||ageratum, zinnia, more lettuce, radicchio|
|6 weeks||bachelor's buttons, agastache, aster, basil, marigold, sweet pea, calendula|
|5 weeks||sanvitalia, cabbage, convolvulus, nicotiana, lavatera, nigella, phlox, phacelia|
|4 weeks||morning 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:
Seed packets, sorted by planting date.
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).
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.
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 basement 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.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.
Although echinacea is a problem-free plant, you may encounter some issues. Avoid bringing pests home with you by carefully inspecting nursery purchased plants.
Leaf miners bore into the leaves of plants. Make a spray using dish soap and water and spray directly onto the leaves of your plant to control them. Neem oil and diatomaceous earth are other effective substances for getting rid of leaf miners.
Vine weevils are black beetle-like creatures that will chew into the top portion of coneflower stems and leave your flowers hanging by a thread. Get rid of the drooping flowers right away to control the weevils. Dump the broken off flowers into soapy water to prevent the weevils from feasting once again on your echinacea.
Japanese beetles eat the leaves and blossoms of growing echinacea, and when an infestation gets bad, it can skeletonize a plant in no time. Spray plants with neem oil and hand pick these slow-moving insects off your plants.
These microscopic mites can be hard to spot. Damage can look like air pollution or scorch, but if you get out the magnifying glass, you’ll see white or yellow carrot-shaped arachnids moving across the leaves. Since the damage is mostly cosmetic, you can leave them alone, but if they drive you crazy, prune off infected leaves.
If you notice little green (or pink, or yellow) bugs all over your growing echinacea, you may have aphids. Blast your plants with cold water and dust them with flour. If you have a bad infestation, try neem oil.
These tiny flies suck the nutrients out fo plants and can stunt growth. Encourage natural predators like wasps and lady beetles and avoid planting echinacea near cole crops to prevent them from moving into your garden. Apply neem oil to get rid of them.
I know powdery mildew well since it often plagues my squash plants. The fungus slowly weakens and kill plants and tends to prefer moist, humid environments. You’ll recognize it thanks to its powdery, white, flour-like appearance. Stop the spread of the fungal infection by immediately getting rid of affected plants. Water from below, so plant leaves don’t get soaked and moist.
Gray mold is another fungus that quickly kills plants. It’s also caused by excess moisture. The fungus first appears grey and then spots eventually turn brown. Your plant will soon wilt and die. Get rid of affected plants and always clean your tools and supplies to prevent spreading fungal and bacterial diseases.
Stem rot (also known as white mold) is caused by a fungus that causes leaves to wilt and turn gray before dying. Avoid overhead watering and leave plenty of air between plants. Keep up on your weeding, because weeds can spread this disease.
This disease is spread by insects like leafhoppers and causes leaf yellowing. Remove diseased plants, control insects and keep weeds away to help keep this under control.
This disease causes black leaf spots. Use copper spray if you get it, and prevent it by avoiding overhead watering and keeping weeds away.
You can start seeds directly in the garden for the plants listed below to get an extra late season harvest. Keep in mind that you'll need to keep the soil moist and not too hot for germination. (Light mulch such as grass clippings can help.)
Consider planting your low growing fall crops inside a small cold frame, so that you can cover them to extend growing and harvest.
To get the printable version of the charts, click the link below. The pdf displays the calendars more nicely than they display on screen.
Adjust the dates for your area and keep them in your garden planner.
Why bother to start your own seeds? It seems like a lot of work, and there will be all those lovely vegetable seedlings at the big box stores and farm stores in a couple of months. It is isn’t it? They will won’t they? Let’s explore these assumptions and talk about the benefits of starting your own seeds indoors.
You control the timing. Imagine having your garden all planned out, the timing of each crop figured out so that you can succession crop each planting bed. But the stores thinks all cool season seedlings go in at the same time. If you wait to buy past their preferred timing, all they’ll have left are straggly, ill-cared for leftovers. If you want to buy ahead of their timing, there won’t be anything to purchase. Starting your own seeds allows you to time their growth enabling transplant just as a spot opens up in your garden.
You decide the variety. Do you want a variety that performs well in your micro-climate? Is taste your determining factor? Would you consider hybrids, or only heirloom vegetables? Whatever is important to you can only be ensured through careful varietal selection. When you start your own seeds you are growing the perfect plant for your needs and desires.
The seedlings handle transplanting with greater ease. Purchased seedlings have rarely been hardened off, which is the process that makes them ready to be transplanted. They are usually too far grown to allow you the time to harden them off yourself before planting. Seedlings that you start yourself have the hardening time factored into their growing period before transplant. One to two weeks before planting out, you take them outside to a lightly shaded and protected area for a few hours. The time is increased daily. By the time you put them in the ground they are already acclimated to your growing environment. This also gives you more flexibility in when you plant so that you can factor in the weather conditions.
Yes, no, maybe. It is more work than driving to the store to load up on purchased seedlings. You’ll start your gardening work a couple of months earlier than if you wait to buy seedlings.
But you won’t drive around town looking for the varieties you want. And you won’t have to rework your garden plan because the varieties available have different maturation times then what you’d hoped for.
You won’t have to drive around town a second time looking for replacement seedlings that are still in good shape. Your successful transplantation rate will be higher since your home-grown seedlings will have first been hardened off correctly. You will spend time potting up seedlings once they’ve sprouted but, if you are like most gardeners, you’re aching to get your hands in soil again anyways.
Determine whether money, convenience, or time are more important to you. There are multiple ways to approach each area of indoor seed starting. Here are the things you’ll need to buy or make to get started:
Seed starting trays & planting medium.
I like the ones that have individual cells in groupings, covered by clear plastic domes. This way I keep the moisture levels high when the seeds are germinating and can see exactly when they come up. The trays come in three parts: the under tray which is where you apply water, the cell tray which is where you put the planting medium and the seeds, and the clear dome cover. A frugal version of this is an array of small plastic cups with holes punched in the bottom and set in an aluminum baking tray. Only fill half way with planting medium (to give room for seedling growth) and cover with plastic wrap. You can also start seeds in seed blocks you make yourself.
You can make your own seed starting mix or buy it ready to use. The important things to remember is that it should be soil-less (to keep it light and airy) and sterile (to avoid introducing disease). Being an older gardener, and a lazy one at that, I buy bags of seed starting mix locally. Since I start my first indoor seeds in January (onions, chives, shallots), I make sure to end the summer with a few bags of the mix on hand for mid-winter. The starter mix can be hard to find locally when no one but me is gardening yet.
Herb and flower seedlings in peat moss.
I use peat pots because they can either be planted along with the seedling or gently peeled off the plant before putting it in the garden. They are biodegradable. Roots that grow through these pots are air pruned which makes the plant stronger. This does add to the annual expenses, but it is a convenience for me. Many people use old sour cream tubs with drainage holes in the bottom. A disadvantage to this method is that roots tend to encircle the seedling if left in the pot too long – this is what happens to those seedlings you buy in the stores.
Some people use sunny windows but this tends to produce leggy, straggly plants. A controlled environment where you can provide lighting for set hours each day works more consistently. My gracious husband built me a super sturdy light table a few years ago which gives me plenty of space to provide natural light (through broad spectrum florescent lights) for my seedlings. You can purchase light stands and tables at varying price levels from multiple sources. Also, check your seed packets since many seeds need dark to germinate and only want light once the seedlings make their appearance.
Most articles on seed starting will advise you to purchase heating mats to put under your seed trays. In my experience, keeping the trays in a room that stays around 65-70 degrees will allow most seeds to germinate just fine without the cost or hassle of heating mats.
You can start very small seedlings within 2-3 weeks of planting time and transplant them out directly into the garden. They’d need to spend their final week hardening off. This is what you’d do if you’re a market gardener. For this method seed blocks are the best way to go. For home gardeners success comes more assuredly by putting these tiny seedlings in the larger pots and growing them on indoors for another 2-3 weeks so that they are large and robust at transplanting time. This helps them deal with garden pests better as well.
January is here, there’s ice and snow on the ground, and it’s almost time to garden! So get your supplies and equipment ready. Tune in later this month to find out which seeds we start indoors and the timing we use for the process. I just completed my seeding schedule for the year so you’ll be looking at what I’m actually going to do throughout the year.
Sheryl Campbell is an heirloom gardener, shepherd, and edible flower educator who owns Bouquet Banquet in Virginia’s Shenandoah Valley. Read Sheryl’s previous blogging with Mother Earth Gardener and Grit and read all of her MOTHER EARTH NEWS posts here .
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