How to Start Spring Plants Indoors (2024)

How to Start Spring Plants Indoors (1)

The best part about having a homestead or small farm is in managing the land. Planning on how it’s used and watching it produce is extremely satisfying. One way to get the most production out of your slice of heaven is to extend your growing season by starting seeds indoors.

Starting plants indoors from seed can save you time and money. It’s also a great way to grow varieties that you and your family (or local farmer’s market) can’t get anywhere else locally. Here’s how to get your spring seeds started indoors, when and how to plant them out, and some troubleshooting tips for common issues you might have.

Before You Start Planting Spring Seeds Indoors

Planning a little up front can save a lot of headache later. Before you start ordering seeds and supplies, identify the area you have available for starting crops. If you have a massive barn area or greenhouse, you’re going to need different supplies than someone who has a spare bedroom or basem*nt. Darker areas will need more light. Cooler areas will need more heat.

Also make sure that any area you choose has sufficient access to water. If you only have a few shelves of seedlings inside the house and a water tap a few rooms away, a standard gallon watering can will do. But if you don’t have a way to get water out to the barn where you have twelve tables of seeds started, there’s going to be a lot of water hauling in your future.

It’s also worth saying that before ordering seed, be realistic about the outdoor area you have for planting. Plan out where you will put each tray of seedlings before you start sowing seed.

Supplies for Starting Spring Plants Indoors

While a few pots on a windowsill are fine for most amateur gardeners, if you’re planting more than a couple of trays, you’ll want to invest in proper seed starting supplies. Seeds started on windowsills often receive uneven light, and need to be turned often. Your setup doesn’t have to be expensive or complicated, though. A few key pieces of equipment can go a long way, and be reused year after year.

Grow Lights

While there are many products out there advertised as “grow lights,” simple shop lights can also do the trick (and are a lot cheaper). Look for fluorescent or LED lights. You’ll want to position your lights a few inches from the top of your seedlings as they emerge, and adjust those lights as your seedlings grow. Either ensure you have a way to adjust lights up or down or a way to position seed trays closer or further from the lights.


Most any type of shelving will do for seed starting, from metal shelves to improvised plywood shelving stretched between cinder blocks. However, keep in mind that you’ll need to position a grow light above every individual shelf. One grow light at the top of a 5-tier shelf won’t be enough light for the seeds placed in trays on the lower four levels. Plan accordingly.

Potting Soil Mix

What is the best soil for starting seeds indoors? Gardeners all swear by different seed starting mixes. What’s most important is to find or create a mix that is fine enough not to prohibit germination, and well-draining. A good rule of thumb is a mix of four parts compost, 1 part perlite, 1 part vermiculite and 2 parts peat moss. Those looking for a more sustainable option than peat moss can try using coconut coir.

If you want to use off-the-shelf mixes, buy a regular potting soil and sift it through a rough mesh. This will catch pieces of bark, sticks, or other large bits of organic matter that could inhibit the growth of seedlings. The finer mix leftover can be mixed with 1 part perlite to 4 parts soil for additional drainage. This will also make your potting soil mix go further.

Seedling Trays (With Cover)

Seed trays, like shelving, can be bought or improvised. From toilet paper rolls with their ends folded under to sturdy, reusable plastic options, there are plenty to choose from. What’s important is that you’re planting into a container with adequate drainage. Keep tray cell size in mind, too. Larger seeds, like pumpkins and other gourds, will need larger cell sizes.

Small or Standing Fan (optional)

The indoors is great for keeping seedlings safe and snug. However, when they start life out in such plum conditions, meeting the big bad outdoors can be a shock to their system. Keeping a regular, light breeze blowing over seedlings as they grow can help toughen them up more quickly. All indoor started plants will need to undergo a hardening off period when moved outdoors. However, those that have been roughed up a little inside already will do better.

Heating Mats (optional)

If you’re starting seeds in an area with temperatures that sink below 60 degrees, or you are trying to start heat-loving vegetables like peppers, tomatoes, or eggplants, you’ll want a heating mat. While cooler season vegetables like onions, cabbages, and kale can germinate in soil temperatures as low as 40 degrees, they germinate faster at around 70 degrees. If your seed starting area is less than that, you’ll want a heating mat under every tray.

Seed Supplier

There are numerous seed companies out there. Many cater to both backyard gardeners and market gardeners, so you can get seed in a variety of quantities. If this is your first time starting seed indoors, be conservative. Remember that everything you plant now will need to be planted out again when you hit your last frost date. Here are some of the easiest crops you can grow.

How to Start Seeds Indoors

When you have all of your supplies ready, it’s time to plan your sowing schedule.

When to Start Planting Seeds Indoors

The timing of your indoor seed starting will depend on your geographic location and the type of seeds you’re starting. Identify your USDA Plant Hardiness Zone. When you know your zone, you can determine your last and first average frost date. These dates are key for managing your growing season. Check the back of your seed packet for recommended indoor planting times. All will include instructions on the best time to plant indoors, or recommend that you sow directly outside.

What Types of Seeds to Plant Indoors

Some types of seeds do better when started indoors than others. Most farmers and homesteaders in temperate zones prefer to start crops like onions indoors as early as January or February. Cold weather crops like kale, lettuce, spinach, cabbages, and Brussels sprouts can also benefit from the early start. Those who live in warmer zones can move or directly sow crops outdoors much sooner.

Crops that don’t like getting their roots moved will fare less well when started indoors. Sunflowers, gourds, peas, pumpkins and watermelons do better when sown directly in the ground on the date indicated on the seed packet.

Pre-Watering Your Soil

The best way to keep your soil uniformly moist is to dampen it before you put it into the seed trays. Saturate your mix with water and stir. It should be moist but not soggy. If you pick up a fistful, squeeze, and water pours out, it’s too wet. You want it to have the give and dampness of a wet sponge.

Filling Seed Trays

Loosely fill your seed trays with the moistened soil mix, leaving a little room on the top. As a rule of thumb, deposit 2-3 seeds per seed cell. Sprinkle soil over the top, and lightly mist with a mister. If you prefer not to pre-moisten your soil, you can set the filled cells into a tray of water so that they soak up additional moisture. Watering your trays from the top with a hose or watering can when seeds are first sown can easily displace the tiny seeds, floating them out and over your trays.

Troubleshooting Common Seed Starting Issues

If you’re new to indoor seed starting, you may encounter one of these common issues. Here are some tips on how to troubleshoot them.

Seeds Don’t Germinate

Always check the seed packet to determine what its germination requirements are. Some seeds actually require light in order to germinate, and must be surface sown. This means sprinkling seeds on the surface of the soil and not covering them with soil. However, most seeds will need to be planted to a depth of about twice their thickness. Any deeper, and the seeds won’t have enough stored energy to break through the surface.

Other seed types, like beans, can benefit from a good soaking in a glass of water overnight. Sweet peas and lupines can be hurried along by nicking or scratching the outside of the seed with a utility or box knife.

Stunted Seedlings

A common mistake that new gardeners make is to underestimate just how much heat hot weather vegetables like tomatoes, peppers, and eggplants need to thrive. A heating mat can help these heat-loving seeds germinate, but when the seedlings pop up into air temperatures below 75 degrees, they may stop growing. Kicking up the air temperature or moving the seedlings to a grow tent can help. However, if left long enough in the cold air, the stunted seedlings will fail to thrive, and will eventually die.

Leggy, Weak Seedlings

If you notice your seedlings are growing very tall and the leafy heads are falling over, it’s usually an issue with lighting. Plants are hungry for light. If their light source is placed more than a few inches from the top of their leaves, they’ll put an excessive amount of energy into their stems at the expense of the leaves. Move your light source closer, or set something underneath the tray to bring it closer to the light. Leggy seedlings can be salvaged if caught quickly enough. If not corrected, seedlings will become too heavy for their stems, and the plants will fall over.

Starting Plants Inside and Moving Them Outside

So you’ve tended your plants for 4-8 weeks inside, and now you’re about at the last frost date for your region. Like most growers, you’re probably eager to get your plants outside. However, the biggest mistake indoor seed planters make is putting out seedlings that haven’t become adjusted to outdoor conditions. Going through this process - called “hardening off” - is key to getting your indoor plants established outside.

Hardening Off Seedlings

To condition your seedlings to the outdoors, you’ll want to place your trays outside on a warm day when temperatures are above 50 degrees. Place them in an area next to a barn, home, shed, or other outbuilding so they have some protection against the wind. Keep them out of direct sun.

The first day, leave seedings out for one hour, then bring them back in. Increase the amount of time seedlings spend outdoors by one hour each day, gradually exposing them to more sunlight. This process should take about seven to ten days, depending on weather conditions.

Planting Seedlings

You’ll want to ensure your ground is prepared before you start moving your hardened-off plants into their final positions. Choose a cloudy day, if possible, to transplant your seedlings. Fertilize as recommended and water them in well. Once your seedlings are out, don’t forget to perform regular food plot maintenance to keep them thriving.

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How to Start Spring Plants Indoors (2024)


How to Start Spring Plants Indoors? ›

start indoors. General rule of thumb for most varieties is to start seeds six weeks before the last frost. Know your growing zone.

When should I start spring plants indoors? ›

start indoors. General rule of thumb for most varieties is to start seeds six weeks before the last frost. Know your growing zone.

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 April too late to start seeds indoors? ›

April is a great time to start to sow your flowers indoors so they can be ready for summer blooms!

What vegetables should not be started indoors? ›

Not every vegetable should be started indoors. There are many varieties that can be planted right into the ground (direct-seed). These are usually the short season vegetables or root crops that don't always transplant well. They include lettuce, spinach, beets, carrots, green beans and others.

Can you start seeds indoors too early? ›

If you start your seeds too early, they will just get leggy and rootbound before you can plant them outside. Even a 4 inch pot can't provide enough room for the roots of an 8 week old plant, so the roots will just start growing in circles around the inside of the pot.

What vegetables to start indoors in March? ›

In late February to early March, start cabbages, kale, broccoli, cauliflower, onions, leeks, endive, escarole, fennel, lettuce, and artichokes indoors. In mid- to late March, direct sow peas, spinach, fava beans, and arugula outdoors. Start peppers, tomatoes, eggplant, Swiss chard, and tomatillos indoors.

What seeds are best started indoors? ›

Seeds that are typically started indoors include long season crops, like eggplants, okra, tomatoes, broccoli and kale. Some plants do not fare well as transplants or need to be transplanted at the right stage of growth so they aren't stunted by stressors.

Can I start seeds indoors in January? ›

Onions, leeks and chives need the largest head start (12-14 weeks), so you may want to start some seeds as early as mid-January. Visit your local garden center for all your supplies and a healthy dose of good advice on starting seeds indoors this year.

What vegetables to start indoors in April? ›

Sow cantaloupe, pumpkins, and squash late in the month. Plant now okra, asparagus beans, Malabar spinach, cherry tomatoes, and sunflowers. Plant and cage tomatoes, peppers, and eggplant. Indoors continue to sow tomatoes, runner beans, and cucumbers.

When to start tomatoes indoors? ›

Quick to germinate and grow, tomato seeds are best sown indoors about six weeks before your average last frost date. (To determine your last frost date, ask a gardening neighbor or contact your Master Gardener program.).

When to start flower seeds indoors chart? ›

Seed-Starting Date Calculator
CropNumber of weeks to start seeds before setting-out date
Safe time to set out plants (relative to frost-free date)
Flower Collections & Mixes*6 to 8on frost-free date
Forget-Me-Not8 to 9on frost-free date
Gaillardia (Blanket Flower)8 to 10on frost-free date
72 more rows

Is it better to plant seeds in morning or evening? ›

Sowing means planting a seed or putting the seed in the soil. Sow seeds early in the morning so the water has enough time to permeate the soil and get warm throughout the day. You can do it in the evening but make sure the seed flats stay warm overnight.

Should I start cucumbers indoors? ›

Luckily, they are easy to start indoors and each plant yields a lot of fruit. Cucumbers are easy to grow indoors and started them 4-6 weeks before May 7 will give a convenient jump start to the season. Plant the seeds about a half inch deep in 3″ pots. I recommend only planting 1-2 seeds per pot as they grow quickly.

What plants don t like roots disturbed? ›

Some vegetable plants don't appreciate or take to transplanting. Many root-type crops like carrots, beets, turnips, and parsnips are not conducive to planting in containers and up-potting. Also, most cucurbits like cucumbers, gourds, and watermelon plants don't like to have their roots disturbed.

Should I start zucchini indoors? ›

Timing: Start zucchini seeds indoors for 2 to 4 weeks before planting them outside. An easy metric is to start seeds right around the estimated last frost date. Harden off zucchini seedlings 1 week before planting. Transplant 1 to 3 weeks after the last frost date.

When should I start bringing plants indoors? ›

WHEN TO BRING PLANTS INSIDE. As a general rule, tender plants should be brought in when nighttime temperatures are below 50 to 55 degrees F, even if they are hardy for your zone. A plant's roots are more exposed when planted in a container versus in the ground.

What happens if you plant too early in the spring? ›

Planting too early in cooler temperatures can cause stunted growth, wilting, surface pitting, foliage necrosis and increased susceptibility to disease. Low soil temperatures can stunt plant growth and prevent root development. Most summer vegetables like soil temperatures of between 55 and 65 degrees.

When should I start feeding my houseplants in the spring? ›

March is a good time to start fertilizing, and most houseplants will benefit from an application once every 1 – 3 months depending on which formulation is being used.

What month is considered early spring for planting? ›

We often get a “false spring” in January or February, but we try to resist this Mother Nature's temptation. We typically start getting our early spring plants — ones that can withstand some cold — the first week of March, and we often see frost in May, so “early spring” usually runs from March into May.

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