Which Is Better: Winter Sowing or Starting Seeds Indoors?
If you’re wondering how to decide if winter sowing or starting seeds indoors is better, you’re in the right place! Organic farmer Jenna Rich will go through some of the pros and cons of each, as well as common mistakes growers make when trying a new method.
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Successful winter sowing has always seemed like an unattainable goal to me, almost like magic. The more I ponder it, the more magical it seems. Setting tiny, vulnerable seeds outside, gasp, in New Hampshire? When I realize nature has been doing all the work for thousands of years before humans came along and built greenhouses, I have to chuckle a little.
Let’s dive into winter sowing versus starting seeds indoors so we can make whatever goals you set for yourself 100% attainable. Which is better? That’s going to be for you to decide.
Seeds featured in this article:
Short Answer
The short answer is it depends on what your definition of “better” is. Whether you start your seeds indoors or winter sow and let nature take its course is a personal preference that depends highly on space, investments, time you want to spend, and what you’re growing.
Long Answer
There are pros and cons to both methods of sowing seeds, and how you do it is based on your personal experiences. If you’re new to either method, I suggest sowing seeds both ways while you get the hang of it. Learning a new way of gardening is always fun, especially in times of ever-changing climate and unseasonable weather patterns.
Let’s get into some of the benefits of each to help you decide which might be better for you and your garden operation.
Benefits of Starting Seeds Indoors
Starting seeds indoors is a popular way of starting plants from seed, and here are just a few reasons growers choose this method.
- Controlled environment. This can, however, be considered a downfall of starting seeds indoors because controlling the environment indoors can be difficult. You may be inside your home, a garage, or an outdoor greenhouse that fluctuates easily. The temperature, relative humidity, airflow, ventilation, and access to light will all affect how things grow.
- Potentially higher germination rates. When seeds are started indoors, heat mats are often used so heat is evenly dispersed, set to a specific temperature for different crops, and can be adjusted for different times of day.
- Control over sowing and harvest schedule. Many growers create and follow a somewhat strict sowing schedule to estimate the harvest time. This allows us to plan when each crop will be available. Starting seeds indoors allows us to stick to this rather than relying on outdoor weather. This is especially relevant for folks growing in particularly hot or cold regions.
- It’s easy to keep an eye on. Many growers, myself included, want to monitor their crops. This way, adjustments can be made immediately if something is amiss.
Factors to Consider When Starting Seeds Indoors
As a home gardener, you may not want to invest a lot of time, space, and energy to devote a large space to starting seeds indoors, and winter sowing may be a good option for you to consider.
Space Constraints
Your growing operation may get to the point that starting seeds indoors no longer makes sense. If you started in a spare room or a section of the basement or garage, there’s only so much space there for seed trays and potted plants.
Investments Required
Growing indoors takes quite a bit of planning and investment items. Some of the things required or recommended are:
- Sturdy tables and/or grow racks
- Seed trays
- Optional humidity domes
- Heat mats
- Optional thermostat for heat mat
- Artificial light setup, if needed
- Seed starting mix
- Fans
- Possibly a space heater
Time Spent
Starting seeds indoors takes a lot of time and energy. Typically, growers use heat mats, making watering 1-2 times a day crucial for seed germination and seedling success. It’s not a “set-it-and-forget-it” method; if you forget, you’ll likely be disappointed in the results.
Alternating trays on heat mats, shifting trays under grow lights, adjusting the grow lights, repositioning fans, and opening and closing vents each day are just a few tasks that should be done every day when growing indoors. If your greenhouse or seed-starting area isn’t in your home, traveling to and from your seeds also adds time.
Crops Being Grown
When I first started growing, I had no idea of the importance of the note on the seed packet that reads, “Store in refrigerator for at least two weeks before sowing.” Some crops require a period of cold stratification, which is crucial to their ability to germinate properly.
When seeds have been dropped naturally from a plant and spent the winter somewhere on the forest floor or roadside, covered by leaves and pine needles and insulated by snow, Mother Nature performs cold stratification for us. The exposure to cold temperatures and then moist conditions when spring rain and snowmelt occur assists the seed coat in cracking open and germinating.
While not all seeds require this, and some may be negatively impacted, winter sowing takes the guesswork out of the controlled environment of a greenhouse because Mother Nature knows what she’s doing. It may not be on our schedule, but winter sowing can be very successful when done efficiently and properly.
Benefits of Winter Sowing
There are many reasons growers are giving winter sowing a shot. Here are some of those reasons.
- Provides a jumpstart for cold-season vegetables and flowers
- Removes the need to cold stratify seeds in your refrigerator
- Works well for growers with limited space
- There is no need to purchase grow lights, fans, or heat mats. Less expensive
- Hardening off seedlings is not necessary
- Hardier transplants and more productive and resilient plants
- It is a fun project to do in the winter months alone or with kids.
- A less expensive alternative to purchasing plant starts if you don’t have the room to start all your seeds. You can start a garden without much effort with recycled plastic jugs, soil, and seeds.
- It takes the guesswork out of cold stratification.
- No need to follow a strict schedule or pay close attention to the weather forecast
- Save high-valued indoor space for heat-loving crops
Challenges of Winter Sowing
Although winter sowing is a method many growers use with much success, it has its downfalls.
- Humidity levels can get too high, causing damping off or other fungal diseases.
- Out of sight often means out of mind. Things can be missed when you’re not directly in front of your seedlings daily. An example would be on a particularly humid day. You’d typically want to crack the milk jug lids to allow air circulation. Another would be in the spring when seeds begin to germinate. Seedlings may get too hot on a sunny day and perish if you forget to move them into less direct sunlight or crack the lid.
- An unexpected cold snap in the spring has the potential to kill young seedlings.
- Pests or critters may damage or eat seeds or seedlings.
Crops to Sow Indoors
Each gardener is free to sow seeds how and when they want to, wherever they choose. However, some should be sown indoors based on crop-specific needs like summer heat. Here are just a few.
- Tomatoes. If you live in a few warmer growing zones, winter sowing tomatoes in late winter may work fine. But for the rest of us, tomatoes should be sown indoors on heat mats where they can safely and successfully germinate. They are also susceptible to fungal diseases when humidity levels are too high. The risk increases the more time passes. Since tomatoes are often stepped up several times, spending a lot of time growing before being transplanted, they should be sown indoors.
- Peppers. Peppers are another heat-loving crop that is very sensitive to cold and will not tolerate frost. Although you can germinate and grow heat-loving crop seedlings successfully, they will not likely be as productive or resilient, which is one of the huge benefits of winter sowing!
- Cucumbers. Cucumbers are sensitive to cold winds and not tolerant of frost. Additionally, some of the improved, disease-resistant hybrids are fairly expensive. Since cucumber seeds are a delicious snack for many critters, I wouldn’t risk winter sowing these guys.
- Various crops like celery, bulbing onions, zucchini, winter squash, and eggplant.
- Annual flowers that aren’t hardy in your growing zone. Stay away from summer-loving zinnias, for example.
Crops to Winter Sow
Any crop that is hardy in your area and is tolerant of cold and frost should successfully winter sow. Others may still work, but you should pay closer attention to them. Germination rates may decrease.
- Perennial flowers. Poppies, marigolds, cornflower, calendula, and snapdragons are great options, but the list of hardy flowers is long.
- Cold-loving brassicas and greens. Lettuce, winter kale, cabbage, broccoli, and bok choy should all have winter-hardy varieties available. Check seed packets for more details.
- Herbs. Parsley, thyme, oregano, sage, and even basil can be winter sown, although I would wait a little longer to start the basil.
Common Mistakes When Starting Out
Winter sowing is fairly low-maintenance, but there are common mistakes that you can avoid. After a while, these habits will become second nature.
When winter sowing:
- Forgetting to feed or not using a high-performing potting mix. Since your seedlings will be in this container longer than they would in an indoor setup, they’ll need more nutrients for the months they’re on their own.
- Over-sowing. Don’t just sprinkle seeds in the jug, especially if they’re very small, because if they all germinate, they’ll be overcrowded. If you sow more because you think germination rates will be lower, go back in the spring and thin as soon as possible to an appropriate spacing.
- Not taking extra precautions when a cold snap is forecasted. If cold-hardy seeds have germinated, cover them with frost blankets and an optional tarp to block wind and protect the vulnerable seedlings. If seeds haven’t germinated yet, this isn’t necessary. Pro tip: Fill a few unused plastic containers with hot water, wrap them in a towel, and tuck them around your seedling jugs to provide warmth.
- Filling milk jugs or outdoor containers with soil too early. The soil should be thoroughly moist when sowing seeds. If filled too early, the soil will dry out.
- Not using enough soil. Fill your container with about four inches of potting mix so the plants have enough room to grow healthy roots and allow them to spread out.
- Sowing seeds too deeply. Follow the same recommendations for direct seeding outdoors. They may not germinate if they’re too deep. Seeds only have so much stored energy to push through the soil surface to the light. If seeds require light to germinate, sprinkle a little vermiculite on top of them before closing the lid.
- Forgetting to check on your jugs. Monitor occasionally for excess mold or mildew, critter damage, and overall health and growth.
- Not providing enough drainage. Drill holes in the bottom of your containers. Check on them when it’s raining to ensure your drainage holes work properly.
- Being a generalist. Remember, some seeds require a cold spell, while others cannot survive. Be sure to know why you’re sowing certain crops in the winter.
- Assuming ‘cold-hardy’ crops can germinate in cold weather. Some crops, such as parsley, can withstand a frost, but only once it’s well-established.
When sowing indoors:
- Starting seeds too early. Pay close attention to the recommended sowing timetable and follow it to the best of your ability.
- Keeping heat mats on too long or too high a temperature.
- Not providing proper air circulation and ventilation. This is crucial.
- Underwatering trays on heat mats. These will dry out more quickly, so they use less water, but you’ll need to water more frequently so the soil doesn’t ever fully dry out.
- Over-sowing
- Inadequate drainage
- Failing to provide cold-stratification for seeds that need it.
Final Thoughts
If you attempt a new way of sowing seeds and fail, keep at it! Gardening is meant to be fun and rewarding, so try not to get frustrated or give up. I’m an advocate of experimenting and finding what works best for you, so go ahead and do some of both so you’re not putting all your eggs, er, seeds, in one milk jug. Don’t compare the results to those growing in different zones, your own results when you sowed indoors, and especially not to folks you see on social media. Results will vary.
How you start your seeds is a personal preference. Growers should take into account how much time, space, and money they want to spend on their seed-starting setup. Trial and error is how you’ll learn, so try new methods, take notes, and have fun!
