Most indoor sowings begin a few weeks before the last spring frost. However, some plants, like the vegetable varieties listed here, grow slowly and require a longer period of time to get started. If you start growing them indoors in winter and plant them in late spring, they will have time to mature by fall.
If you’re interested in outdoor sowing, here are two winter sowing methods.
Grow slow-growing vegetables early.
Indoor seeding is an easy way to extend the growing season and allows you to grow a much wider variety of plants than you can with direct sowing outdoors alone.
Seed bags usually recommend a specific schedule for starting seeds indoors (weeks before the last frost) to root the plants for transplanting outdoors in the spring.
What surprises gardeners is that not all varieties of the same species have the same duration.
For example, the number of days until maturity is early girl The shelf life of tomatoes is only 50 days. brandy wine For tomatoes, it takes twice as long, 100 days.
Aspa block broccolini It takes 56 days santi broccoli It will take up to 115 days.
Even the same vegetables have big differences!
For this reason, it’s wise to read your seed packets, flag slow-growing varieties, and start growing them much earlier in late winter.
Make sure you have space under your grow light not only for the seedling tray, but also for moving the plants to larger pots (3 to 6 inches in diameter) as they grow.
I use this system to sow batches every two weeks from winter onwards to ensure everything starts on time.
To get started, it helps to know the average last frost date and the typical number of frost-free days from spring to fall. We have listed this calculator and other useful items in the Resources section.
Start slow-growing vegetables earlier
timing example
This chart allows you to grow them indoors for about 12 weeks or 90 days until the last frost.
Last frost in March: Start these seeds in December Last frost in April: Start these seeds in January Last frost in May: Start these seeds in February Last frost in June: Start these seeds in March Start these seeds in
I’ve referenced some of my favorite seed catalogs to give you some examples of these. As mentioned above, check your seed packet for specific growing instructions.
broccoli
Early broccoli: Early broccoli is fast-growing and often grows best in cool climates. If you want to plant outside in the spring, sow the seeds indoors in the winter. Santee Broccoli (80-115 days) Calabrese Broccoli (60-90 days) Purple Sprouting Broccoli (90-100 days) Romanesco Broccoli (75-100 days)
celeriac
Giant Prague (110-120 days) Brilliant (105-115 days) Monarch (110 days)
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celery
Tall Utah (90-100 days) Golden Self Blanched (90-120 days) Tango Hybrid (85-90 days)
eggplant
green onion
Giant Musselburgh (105 days) Othina (120 days) Splendid (95-105 days)
onion
Sweet onions, especially, can be slow to grow. It takes a long time to grow bulbs this big.
Walla Walla (125 days) Sweet Spanish (110 days) Trident (115 days)
green pepper
Chili peppers (Capsicum chinense), including habanero seeds, take 90 to 120 days to mature after transplanting. Anaheim (75-80 days) California Wonder (70 days)
tomato
Mortgage Lifter (85 days) Amana Orange (80 days) Cherokee Purple (80 days) Brandywine (90-100 days) Chef’s Choice Orange (75 days)
resource
What is Days to Maturity?
Days to maturity or days to harvest is the average number of days it takes a plant to reach maturity. Depending on the type of plant, this could be when vegetables are ready for harvest or when flowering plants have bloomed. This is a rough number to help you plan.
Although there is no universal consensus, I use the following values for my calculations:
For direct sowing outdoorsCounting begins when the first true leaf appears after germination. Once the seeding starts indoorscounting begins when transplanted outdoors.
Again, this is just a rough number. Factors like weather and other growing conditions can throw things off. Plants grow rapidly only under optimal conditions, but factors such as excessive heat or drought can slow or stop plant growth. In addition, growth slows as temperatures drop and daylight hours decrease as autumn approaches.
Knowing the estimated number of days to maturity is most useful for fruiting plants that take longer to flower and set fruit during the growing season, such as tomatoes, zucchini, peas, and watermelons.
Vegetables grown solely for their stems and leaves are not a problem, as they can be harvested at any time.
Find frost dates and hardiness zones
Plant hardiness zones | 
United States | 
Canada
These can be found on the seed packet or on the plant tag to help you make a selection.
Average Frost Days | Use this calculator at Almanac.com. Enter your city, state, or province to find out the first and last frost dates and number of frost-free days.
Ecoregions | Learn about local native plants, animal species, and environmental conditions and choose gardens that benefit the ecosystem.
More information: Understanding frost and freeze for gardeners
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Seed start for beginners
Sow seeds inside, grow outside
Written by Melissa J. Will
new edition |Everything you need to start indoor seeds for indoor and outdoor plants. Grow whatever you want any time of the year.
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