It’s time to plant some seeds! So how should seeds be started? Where do you even start? In this article (with new video demonstration!), we’ll show the curious how it’s done! Let’s plant some seeds together, talk about how to encourage them to germinate, and uncover a few typical blunders.
The Hindi term for seed is bija, which literally means “life containment.” This is an excellent description for these small wonders, which contain everything required to create a new plant. This time of year, we are up to our elbows in dirt, starting more seeds indoors each week!
Why We Start Seeds Indoors?
There are many benefits to sowing seeds indoors:
- That obviously offers you an advantage over the growth season, which may lead to more abundant harvests.
- It is truly required by a number of plants. Warm season plants, such as tomatoes, peppers, and eggplant, cannot be planted too early in the spring due to the chilly soil. In many regions (including New England and Midwest), there are not enough growing days for those plants to get to harvest if they’re started outside. Planting seeds inside gives you a few more weeks of growth time, which may make all the difference. In warmer regions, starting seeds indoors can allow you to get in an extra round of crops (especially cool-weather crops) before summer heat stifles growth.
- If you do not seed indoors, you will need to purchase young plants known as “transplants” or “starts” from a garden center or nursery. Although some nursery starting plants are well-grown, others may be of low quality and may not survive after they arrive at their new home. Planting your own seeds results in healthier beginnings since you can care for them from the outset.
- There is a considerably broader choice of kinds available as seeds—varieties that you would never discover in a six-pack at your local garden shop!
- You will be able to tell how they were raised—organically rather than chemically. You can time the plants to be ready for when you want to plant them.
- Lastly, seeds are far less costly than purchasing plants from a garden center.
Warm-season veggies aren’t the only ones that can be grown from seed. Many vegetables—such as carrots and radishes—do best when started from seed, as they dislike having their roots disturbed once they start growing. Look below for a list of which seeds should be started inside vs outside.
Which Seeds Should You Start Indoors?
It is not necessary to start ALL seedlings inside. In truth, most veggies grow well when grown outside and prefer not to be transplanted. Ultimately, it’s important to consider how each type of vegetable grows in addition to where you’re growing it.
Use the table below to find out which crops are normally grown inside and which are typically started outside. Remember that there is no hard and fast rule regarding what you may start inside and outdoors; it depends on your expertise, personal taste, location, and the plant itself. In general, we discover:
- Broccoli, brussels sprouts, cabbage, and tomatoes are all best started indoors. Those with a slower root development, like cauliflower, celery, eggplant, and peppers, should also be started indoors.
- Delicate vegetables, such as tomatoes, eggplants, and peppers, are especially sensitive to the low temperatures of spring, so it’s better to start them inside and protect them from the unpredictable weather.
- Plants that do not transplant well and are therefore best started outdoors or in containers include cucumbers, muskmelon, pumpkins, squash, and watermelon. They are all fragile, so don’t plant them outside while frost is still a hazard.
- Some plants are actually resistant to transplanting. Root vegetables, like carrots, turnips, and beets, don’t like having their roots disturbed, so it’s usually safer to just start their seeds outdoors in the ground rather than transplant them later on. Plants with lengthy tap roots, such as dill and parsley, dislike being transferred as well.
- Lastly, vegetables like radishes and peas grow so quickly and are so cold tolerant that it only makes sense to plant them right away!
Seed-Starting Preference by Plant
|Plant||Start Indoors||Start Outdoors (Direct-Sow)|
When to Start Seeds Indoors?
It is critical to plant seeds at the proper time. Let’s not go too far ahead of ourselves! Sow too early and plants may have outgrown their pots before the weather has warmed up enough to plant them outside. But start seeds too late and they won’t have enough time to reach maturity before the end of the growing season. It’s a delicate balance!
The Almanac’s Planting Calendar lists the ideal dates to start your vegetables. This tool is tailored to your zip code and local frost dates.
- As a general rule, most annual vegetables should be sown indoors about six weeks before the last frost in your area. Check your local frost dates.
- The seed packaging will usually state when the seeds should be started indoors. For example, it may say, “start indoors 8 weeks before last expected frost date in your area.”
Our Garden Planner also includes all of the planting dates for the season, which are coordinated with your overall garden plan. The Garden Planner utilizes climatic data from your local weather station to determine the optimal range of planting dates for each crop in your plan. It’s color coded to show you the dates for seeding inside and sowing outside, as well as growth and harvesting!
Equipment Needed for Seed-Starting
You simply need a seed-starting mix, containers, and a decent source of light to start seedlings.
Let’s start with our seed-starting mix . For large seeds like beans and squash, use an all-purpose or multipurpose potting mix. But, for finer seeds, we suggest using a seed-starting mix (designed especially for starting seeds). We also appreciate the seed-starting mix since it has less nutrients than the seed itself. Be certain that your mix is peat-free. (Extracting peat releases carbon and destroys natural habitat, so we prefer to use a more-sustainable alternative such as coconut coir.)
The right container: You can sow into pots/single seed trays or into plug trays/module trays. Each has its own set of advantages:
- Sowing into pots Using a single tray container saves room since immature seedlings take up less space at first. It’s a more efficient use of seeds, too, because you can germinate the seeds in a pot and then transfer every single seedling into its own pot or plug. Sowing into a single container is especially excellent for planting extremely small seeds like basil or easy-to-transplant flower seeds. For easy, cool-season crops—everything from onions to celery to cabbage—you can sow multiple seeds in the same container seed flat. To conserve space, you may stack trays after sowing. After two or three days, begin daily monitoring for indications of germination and then transfer them to the greenhouse or cold frame to continue developing. You may also keep seedlings growing inside, using grow lights to guarantee vigorous, uniform development.
- Plug trays Containers, on the other hand, have distinct compartments for each seed. They eliminate the need to transplant seedlings as often, resulting in less root disruption. Just put them into the plugs and let them develop until it’s time to plant them, but they may need to be transplanted into larger plugs or pots if the roots outgrow their plugs before it’s time to plant them. Two or more seeds are usually sown per plug and then the germinated seedlings are either left to grow on as a cluster or thinned out to leave the strongest seedling in each plug. Trays with smaller plugs are ideal for most leafy greens and radishes, particularly if they will be transplanted soon (within three or four weeks of sowing). This approach is also suitable for cluster-grown crops such as beets or beetroot and salad onions.
We often repurpose food containers such as yogurt cups and sour cream containers as seed starting containers. Just empty them out and make a few drainage holes in the bottoms of them. They are generally large enough to house one or two small seedlings for a few weeks. Seedlings will eventually need to be transferred into their own pots.
Well-crafted stiff plastic containers and trays may survive for many years, but if you wish to eliminate plastic, seek for alternatives made of biodegradable fiber.
Rows of seedlings are started in broad, shallow, flat pots.
How to Sow Seeds?
Sowing in a pot or a plug tray is a simple process.
- If sowing in a pot, fill it to the brim with the potting mix, then tamp down to a firm level. It’s hard to over-firm, and seedlings prefer plenty of potting mix to sustain them. If you’re using plug trays, fill them all the way to the top and tamp them down to settle. Add a bit more of the mixture, then brush off the excess.
- Plant your seeds in the depressions at the depth specified on the seed package. The majority of seeds may be gently crushed into the mixture with your fingertips or the eraser end of a pencil. Choose the biggest, healthiest-looking seeds in the package when deciding which seeds to sow for the maximum chance of germination. Many vegetables, including common crops such as salads, onions, beets, peas, and radishes, may be sown in pinches of three to five seeds per plug for planting out as a cluster of seedlings (to later be thinned out). Beans, for example, are seeded individually into deeper holes created with a finger, pencil, or dibber (a specific seed-sowing instrument).
- When you’ve finished sowing, cover the seeds with potting mix to the depth specified on the seed package.
- Label your sowings, particularly if they are different types of the same plant. This is critical! You may believe you will remember, but it is much too simple to get confused, especially if you have seedlings with extremely identical leaves. Fill in the date of sowing and the kind you’ve planted.
- Carefully water the pots or trays with a watering can equipped with a fine sprinkling rose or a clean turkey baster. A pitcher’s vigorous release of water may dislodge seeds or young plants’ delicate roots. A mist sprayer is mild, but it might take a long time to thoroughly soak the mix. Let to drip off the surface before repeating. Wet the mixture thoroughly so that the seeds awaken from their sleep! Don’t worry; if the mixture is excellent, it’s difficult to overwater at this stage; any extra will just drain out the bottom.
Watch this video to see the seed-starting advice in this article come to life. Ben will teach you exactly how to sow like an expert!
Speeding Up Germination
We’re all eager, wanting to see those seeds sprout as soon as possible. The best way to achieve that is to give your seeds as close to ideal conditions as possible, which in most cases means a little warmth, so bring these early sowings indoors to germinate.
- The optimal temperatures should be indicated on the seed packaging. In most instances, a tucked away corner of a warm room should work just fine, or on top of any appliance that gives off a little warmth—the top of fridges or freezers for example, or on a warm mantelpiece for warm-season crops like tomatoes, for instance.
- Cover the plug tray or pot with some form of transparent cover to keep the potting mix from drying out and the conditions nice and cozy. For this, you might use a humidity dome or propagator cover. Or, just cover loosely with plastic and poke a few holes in the plastic with a toothpick for ventilation; mold growth can occur if containers are not allowed to “breath.”
- Seed packs normally indicate how long germination should take, but nothing beats frequent inspections—and that’s half the fun anyhow!
- After about half of the seedlings have sprouted, take them from the humidity dome or plastic covering, and relocate them to a location with excellent, strong light.
Hang the lights in such a way that they may be adjusted to stay 4 inches above the plants as they develop.
Let There Be Light
Planting seedlings on a windowsill, which seldom provides the same quality of light as outside, is a typical error. You can try turning seedlings daily to help them grow straighter, but more often than not the result is leggy seedlings that struggle to recover. Low light levels, rather than cold, are frequently the killers at this time of year, at least for cool-season crops. So, if it’s early in the season and you don’t have a suitable outdoor protected structure such as a greenhouse or cold frame, it might be worth investing in some full-spectrum grow lights.
- Grow lights don’t have to be anything special. An LED or fluorescent light fixture that’s “full-spectrum” (i.e., produces light in the full range of the visible spectrum—like the Sun) can usually be found for under $40 at a local hardware or department store.
- With inexpensive grow lights, the lamp unit can be adjusted up or down. Preferably, the lights should be 4 to 6 inches above the seedlings’ canopy. That’s far enough above not to be too warm, but to give a good, strong light. When the plants expand and need more room, raise the light unit.
- Up to 16 hours of light every day is sufficient. In fact, in most cases, the longer you leave them on, the quicker seedlings will grow, so this is a good way to catch up on growth early on in the season. (Keep in mind that plants need periods of darkness as well, so don’t keep your lights on all the time!) Many gardeners turn on lights when they get up in the morning and turn them off when they go to bed, which means they’re on for 15 to 16 hours. You might also set your grow lights on a timer.
- Plants may be moved from grow lights to outside or under cover outside when it’s warm enough or, more often for cool-season crops, when light levels have increased somewhat more.
How to Transfer Seedlings?
If you raised seedlings in a tray, you’ll need to transplant—or prick out—seedlings into their own pots after they germinate. When they have two pairs of leaves—usually a set of seedling leaves and the first set of true or adult leaves—this is the optimum time to do it. (See the video below.) But, seedlings may be moved much earlier than this—as soon as they are large enough to handle. Don’t put off transferring your seedlings since you don’t want them to grow overcrowded, which may lead to problems like leggy seedlings or disease. It’s also a lot easier to separate seedlings out when they’re small.
- To transplant seedlings, fill new pots with your potting mix; at this stage, an all-purpose or multipurpose potting mix is just fine. After drilling your holes, gently remove the seedlings from their nursery container. Lift out just what you need if you aren’t transplanting all of the seeds.
- Separate the seedlings and place them in their waiting holes. Only ever handle seedlings by their leaves; if you damage or crush the fragile stem, the seedling’s had it!
- Also, try to avoid injuring the roots as much as possible. One method is to transport as much of the potting mix that is surrounding the roots as possible with you. This is one reason, in fact, why working with really young, small seedlings is often better: they are really quick-growing and their roots are nowhere near as extensive as more established seedlings, so there’s less root to damage.
- If seedlings are a touch lanky, place them a little deeper to assist support them and get them back on track.
- Firmly pack around seedlings. After that, water the seedlings gently using a watering can. Don’t worry if the seedlings become a bit flattened; they’ll recover quickly.
- Monitor the soil moisture of your seedlings and plants on a regular basis. To determine how heavy the pot is, insert your thumb into the potting mix or just pull it up. With more experience, you’ll acquire a better sense of this, but the heavier it is, the more water it contains and the less likely it is to require watering. Check our video on Pricking Out, Potting On, and Transplanting for more information.
Hardening Off Seedlings
Tender crop seedlings must be progressively exposed to outdoor environments before planting, a process known as “hardening off.” Suddenly moving plants from a stable environment to one with wide variations in temperature, light and wind can seriously weaken plants.
Start hardening off most plants around 7 to 10 days before the last frost date in your location. Check our Planting Calendar for safe planting dates and move backwards from there. Withhold fertilizer and water less often.
- About 7 to 10 days before transplanting, set the seedlings outdoors in dappled shade for a short time. Make sure the location is wind-free.
- Begin with an hour every day and progressively increase the length of time plants spend outdoors until they are out all day.
- At this time, keep the soil wet at all times. Rapid transpiration may be caused by dry air and spring winds. Whenever feasible, transplant on cloudy days or early in the morning, when the sun will be less intense.
- Cool-season crops do not need as much hardening off as warm-season crops. Crops such as lettuce, onions, beets, or peas can go straight outside as soon as the ground is ready, meaning that the soil is no longer cold and wet, and has reached around 50ºF (10ºC). Warm-season crops, such as tomatoes and peppers, will need acclimatization.
- A great way to toughen up plants—whether indoors or under cover in a greenhouse or cold frame—is to run your fingers lightly over the foliage. This simulates wind to make plants stronger. You may also use a fan inside for this.
- If outdoor conditions allow, plant seedlings out while they are still quite young—sometimes as soon as 3 to 4 weeks after first sowing. Seedlings that are younger tend to establish faster than those that have grown root bound in their pots.
See our video on How to Harden Off Plants.
If you’re not able to be around to bring your seedings back and forth from the outdoors, another option is to place your seedlings into a cold frame and gradually increase the amount of ventilation by opening vents progressively wider each day. Be careful to turn them off entirely before it gets dark. (For cold-weather protection, see how to build a cold frame.)
Final Thoughts and Tips
- Be knowledgeable about seeds. Obtain seed catalogs from several companies and compare their offering and prices. Some regional businesses may sell variations that are more suited to your location.
- Create a list of the things you want to cultivate. A good rule-of-thumb is to imagine your garden one-quarter the size that it really is. This allows for good spacing practices! Popular starter veggies may be found in Vegetable Growing for Beginners.
- Gardeners with experience constantly hedge their bets and plan for some losses. So many elements contribute to successful gardening. Is this year’s weather particularly warm or cold? Are pests such as slugs or birds going to consume your initial seedlings? That’s why it’s a good idea to sow seeds in small batches a few weeks apart.
- It’s good getting an early start since it doesn’t matter if you lose those seedlings; you can always plant more.
- Based on your arrangement, the Garden Planner calculates how many plants you’ll need. But, hey, sow a few more than you’ll need as spares, just in case, or so you can select the very biggest, healthiest seedlings to plant out.
- If you have excess seeds, pour them back into the package over the pot you’ve just seeded. That way if you drop any, they’ll end up sown with the right batch of seeds, rather than being wasted or mixed up in the spare potting mix!
- Install pest control measures like as netting or fleece row coverings for bird protection and slug traps.
- Several fast-growing crops are harvested often. As an example, consider lettuce or radishes. Sow a small plug tray every couple of weeks throughout the growing season and that way you can look forward to a succession of harvests, rather than them all coming at once. It is clever planning!
More Reference Material
Browse the Almanac’s Growing Guides collection for planting, care, and harvesting instructions for all common vegetables, fruits, and herbs.
We’ve also compiled a list of all of our greatest basic gardening articles. Learn to Garden series. From selecting the right gardening spot to choosing the best vegetables to grow, our Almanac gardening experts are excited to teach gardening to everyone—whether it’s your 1st or 40th garden.
Should I start all my seeds indoors?
There are several advantages to starting seeds indoors, including an early harvest. Although certain crops may be directly sown, others can be started inside and harvested later. Another advantage of beginning seeds inside is that you can produce long-season crops in short-season settings.
Should I germinate seeds indoors?
Starting seeds indoors gives your vegetables, herbs, and flowers a head start so they can grow larger and have better (and longer) harvests or flowering periods. It’s simple and enjoyable to grow seedlings inside with a few basic materials and a little patience.
What seeds should not be started indoors?
6 Plants You Should NEVER Start Indoors
- Root vegetables. Root crops simply don’t transplant well. …
- Squashes. Squashes (squash, zucchini, pumpkins) and cucumbers grow extremely fast and large. …
- Corn. Corn typically doesn’t transplant well. …
- Beans. Beans grow quickly as well. …
- Peas. Peas are similar to beans. …
- Cucumbers. …
Should I direct sow or start indoors?
The Advantage: Indoor seed starting allows you to have the greatest control over your seedlings. You can simply monitor the germination rate of your seeds and provide them with more moisture or warmth as required. Seedlings are less susceptible to pests and illnesses in a controlled environment.