When Should I Start Seeds Indoors - Mosser Lee (2024)

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First, create your garden plan. Click here to see our guide for a successful garden plan.

Once you have created your garden plan, make a list of all the plants you intend to plant. This will help you determine how many plants of each variety you will need for a successful harvest or display. At Mosser Lee, we recommend planting at least 20% more seeds than you need. You may find additional spaces that need filling and of course, seedlings are always wonderful to share with neighbors or with plant swappers.

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What do I need to Start Seeds Indoors?

Many people are very successful in starting their seeds with minimal equipment. When you have a bright sunny eastern-facing window, seed starting can be very cost effective. You can start seeds without expensive custom trays or containers.

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Thoroughly wash yogurt or pudding containers and cut drainage holes. You can do the same with plastic milk or juice jugs, cutting them down to about 6” high and adding drainage holes. Collect toilet paper rolls and fold over about an inch, creating a bottom. Bonus – paper rolls can be moved directly into your garden as they will compost, providing nutrients to your soil.

There is one thing you can’t skimp on. A high quality seed starting mix is vital for germination and growth success. Our SucSeed® Seed Starter medium is proven to help your seedlings develop strong and robust root systems, prevent overwatering and provide fast and high germination rates. It’s peat-free, lightweight and recommended by the National Home Garden Club.

When the seed starting bug really takes hold, you may want to purchase items that allow you to better control the seedling’s environment.

Do I need a Grow Light? What kind of Grow Light should I get?

Grow lights help prevent leggy seedlings. When the seeds aren’t stretching for light, they grow more compactly, giving you fuller, more robust leaves instead of long, reaching stems.

In the past, grow lights were large, clunky, and cost-prohibitive. Today’s LED technology has now made grow lights adaptable, inexpensive and easy to manage. Shop lamps and fluorescents will work fine. Photosynthesis happens best in a red/blue combination and doesn’t really require “daylight” spectrum bulbs.

You can find grow lights with:

  • Bendable arms. Position your light close to the seeds, moving lights up as plants grow.
  • Timer capability. Seedlings typically need 16-18 hours of light each day.
  • Multiple settings. These can help you accommodate plants with different needs.

Should I use a heating pad to start seeds indoors?

Beware – a heating pad that you might use for an aching back is not appropriate for seed starting. These pads are not waterproof, do not maintain a steady temperature and can easily fry out your seedlings. Purchase a certified heat mat or germination heat mat created specifically for seed germination.

Seeds started at a constant, warm temperature are more successful. They will:

  • Germinate sooner
  • Produce healthier roots
  • Avoid damping off

What is damping off?

Damping off is the most common problem in starting seed indoors. It’s caused by a variety of water molds and fungi. Healthy young seedlings can be affected overnight. They blacken and die as stem rot occurs at soil level, causing the plant’s tissue to collapse. Because Mosser Lee’s SucSeed® Seed Starter is made of sustainably harvested, milled long-fibered sphagnum moss, the fungi and molds cannot grow, so damping off is avoided.

What kind of seed trays should I use when starting seedlings indoors?

At Mosser Lee, we are committed to preserving and improving the environment in everything we do. For many gardeners, plastic is the bane of their existence; it holds mulch, soil, plants and seedlings. It seems to contain nearly everything gardeners buy.

Reuse those plastic containers and seedling trays you’ve already purchased by washing them in a light bleach solution and warm water and then drying thoroughly. Consider using reusable and recyclable sheet pans to hold your seedling containers.
Avoid peat based products. Peat moss is not considered a renewable resource and harvesting peat from bogs releases 2 billion tons of greenhouse gas into our atmosphere each year. Long-fibered sphagnum moss products, like the ones from Mosser Lee, are harvested sustainably, with the moss renewing itself year after year. It’s compostable, non-toxic and has been recommended by the USDA since 1944.

Plant hardiness zones and Seed Starting

Sometimes called a grow zone, understanding your plant hardiness zone is essential for deciding when tostart seeds indoors. The USDA created this standard to help gardeners determine which plants will thrive in their region and, most importantly for seed starting, your average last frost date.

When you live in Zone 2, the upper reaches of Minnesota in the United States, you could see a frost as late as June 4th. When you live in Zone 6, much of Kansas, Missouri and Ohio, your latest frost comes about April 21. Annuals that have been started from seed should not be transplanted outdoors until the last frost date has passed.

How to Read a Seed Packet

When you purchase seeds from a reputable source, you’ll be given a wealth of information on the packet about how to start seeds indoors. You’ll see planting depth recommendations, soil and light recommendations and, to help determine your seed starting date, days to transplant. For instance, your packet may read “start seeds indoors 2-3 weeks before transplanting.” From your last frost date, April 21 for example, count back 14-21 days to arrive at your seed starting date, determining the best indoor starting dates are April 1 to April 8th.

Cold Stratification and Scarification

While many types of seeds can be sowed with no preparation, there are some that will need special care. Seeds such as prairie coneflower, pincushion and milkweed need cold stratification. Other seeds will need scarification, like nasturtium, sweet pea and morning glory. When going through all the steps involved in how to start an avocado seed, scarification is number one on the list of things to do.
Are you hoping to grow milkweed to help support the Monarch butterfly? Click here and we’ll send you a packet of seeds with growing instructions – free!

Indoor Seed Starting Chart

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Indoor Seed Starting Groups

Starting seeds in groups can be helpful to your schedule and give you a bountiful harvest. Consider starting these plants at roughly the same time. For instance, you’ll start tomato seeds indoors at the same time that you’ll start eggplant. Ratatouille, anyone?

Double check your cold loving plants such as cabbage, broccoli and brussel sprouts. You may want to start those seeds indoors when it’s still snowing outside!

Group A – Start these plants indoors 10-12 weeks (70-84 days) before your last frost.

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Group B- Start these plants indoors 8-10 weeks (56-70 days) before your last frost.

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Group C – Start these plants indoors 4-6 weeks (28-42 days) before your last frost. While many of these can be direct sown outside, they can also benefit from a little extra boost to get a strong healthy start.

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Can I start seeds indoors earlier than recommended?

The short answer is yes, but you’ll need to make some adjustments. When you begin earlier than recommended, little seedlings can become big seedlings very quickly and will need to be hardened off and transplanted earlier, while there is still the threat of frost which will kill annual flowers, vegetables and tender perennials. Starting seeds indoors too early makes it a struggle to keep your plants thriving. You may want to invest in hoop houses, cold frames and row covers to extend growing times.

The benefit of starting seeds earlier is that you are moving up your harvest date and can enjoy your favorite veggies and a vibrant floral display a bit sooner. Consider staggering your planting schedule to extend your harvest throughout the season. Many gardeners prefer to divide their quantity of seeds into portions, starting one portion each week for several weeks. This way, plants grow and vegetables mature at different times, ensuring a steady supply throughout the season.

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Can I start seeds late?

Absolutely! Your plants will be smaller than plants sown earlier, but when starting indoors in a high quality seed starter, you’ll achieve robust root growth for healthy seedlings.

Which seeds should I direct sow?

Many vegetable and flower varieties do very well when direct sown or planted directly into the ground or outdoor container. Check your seed packet to determine the grower’s recommendation. Some vegetables such as peas and spinach can be sown before your last frost date; that information will also be on the packet.

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Find More Gardening Projects:

How to Start Seeds Indoors

In most northern climates, gardeners have long known the many benefits in starting their own vegetable and flower seeds indoors. It is easy and fun. With this tutorial, you will learn about the joys and feel the pride in growing your own plants from seeds.

How to Plant Nursery Stock

Many Gardeners choose to plant Nursery Stock Seedlings when growing vegetables like tomatoes, and peppers. Often the journey from seed to soil for Nursery Stock Seedlings can be stressful. Use Long-Fibered Sphagnum Moss to decrease your new seedlings stress and increase your yield this year.

How to Create a Terrarium

Planting a terrarium is ideal for gardening indoors where space is limited for potted houseplants. Terrarium gardens also are great for those who would like to try their hand at first time gardening.

Share your Experience with Us!

We would love to see your creations. Make sure you tag us on Social Media and upload your creations to theYour Creations Gallery. Visit us onFacebook,Instagramand make sure to follow us onPinterest.

When Should I Start Seeds Indoors - Mosser Lee (2024)

FAQs

What is the best date to start seeds indoors? ›

When to start seeds indoors. start indoors. General rule of thumb for most varieties is to start seeds six weeks before the last frost.

When should you sow seeds and how do you figure that out? ›

Determining the Planting Date Using a Calendar

So if your last frost date is 4/19 then count backwards from that date 8 weeks. Those seeds should be started around February 22. If you start the seeds around that date, the seedlings will be ready to transplant out into the garden around the last frost date.

How many hours of light do you need to start seeds? ›

Most seeds will not germinate without sunlight and will perform best with 12 to 16 hours each day. Indoors, place seed containers in a sunny, south-facing window and give the container a quarter turn each day to prevent the seedlings from overreaching toward the light and developing weak, elongated stems.

When to start stock indoors? ›

Sow and Plant

Sow stock seeds in midsummer to have seedlings to set out in early fall, or sow indoors in late winter and set plants out at about the time of your last spring frost.

Can you start seeds indoors too early? ›

Resist the urge to start seedlings too early in the season. It is easy to get excited for spring, but starting seed too early leads to challenges later. Seedlings planted too early get large and lanky by the time they can be planted outside, and lanky seedlings do not transplant well.

What seeds should not be started indoors? ›

Seeds for Root Crops Should Not Be Started Indoors

For that reason, it's best to start root crops like carrots, beets, radishes, and even potatoes in the soil where they'll grow.

What seeds are best to start 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.

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!

How many seeds to plant when starting indoors? ›

Add one seed to each pot or cell. Use the crease of the seed packet or place seeds in a creased piece of paper to help direct the seeds where you want them to go. Sometimes not every seed will germinate. To increase your chances of success, add 2-3 seeds to each pot and thin out the extras once everything has sprouted.

Should you water seeds right after planting? ›

Moisture Matters – After planting, water seeds with a gentle mist or shower. Avoid using a strong splash or spray, which can dislodge seeds. It is vital to keep soil consistently moist.

Can I use a shop light as a grow light? ›

According to Pilarchik, any white LED shop lights with a brightness of 5,000 lumens or higher and a color temperature of 5,000 K or higher—like the Hyper Tough shop light—can be used as grow lights for seedlings.

What is the best light for seedlings indoors? ›

Light color

If you are just using grow lights to start seeds or to grow leafy vegetables, stick to lights that are labeled either as blue-green spectrum or balanced light spectrum. It is increasingly common for lights to be labeled “for greens and seeds” or “for flowers and fruit”.

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.

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.

How to calculate when to start seeds indoors? ›

To determine the best time to start your seeds indoors, check the back of the seed packet to see how many weeks the seed needs to germinate and grow before it's transplanted. Using that number, count backward on the calendar from the average last frost date – that's May 15th in our area.

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 annual flower seeds indoors? ›

Tender annuals can be sown directly in the garden, but only after all danger of frost has passed. These cold-sensitive seeds can also be sown indoors four to six weeks before the last spring frost date. Transplant into the garden when you are confident that nighttime temperatures will stay above 40 degrees F.

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