When to Start Sowing Seeds: A List of the Earliest Seeds to Start Indoors

A guide for which seeds can be sown the earliest based on your region’s climate. Includes information on last frost dates and hardiness zones and types of vegetable seeds to sow in the weeks before spring officially arrives.

While most gardeners are still poring over their seed catalogs there are always the impatient ones (like me) who want to get growing. Fortunately, there are seeds that can be sown this time of year if it’s done undercover. But take heed, only sow the ones that benefit from being started early or you risk losing your plants, time, and money. These are my tips for sowing the first seeds including which ones can be sown the earliest. There are even a few that benefit from an early start.

Starting Seeds Too Early Can be Risky

Online, and mainly in Facebook gardening groups, I’ve seen quite a few growers posting photos of seedlings they’ve started early. It’s such an optimistic sight to behold! Young green seedlings stretching out of the compost seeking the sun. Sadly, unless these gardeners are set up with grow lights, it’s quite likely that their precious new plants will keep stretching and stretching. The young plants become ‘leggy’ and sick and most of the time don’t make it.

The fact is, no matter where you are in the northern hemisphere, it’s still winter. The sun could be shining and some days might even feel a bit balmy but don’t be fooled – snow may not be that far from your future. The time for planting crops outside in the garden is still months away so you may want to reconsider sowing seeds too early.

However, SOME plants do benefit from an early start. They include the types listed below in the categories to sow eight to ten weeks before your last frost date. If you have a heated propagator, grow lights, and an undercover place to sow seeds then get sowing. I share tips for starting seeds indoors during winter in another piece.

When to Start Sowing Seeds

The answer to this question comes down to your region’s climate. Obviously, you wouldn’t sow spring crops in April if you lived in Australia. That’s an extreme case of seed sowing differences though. The main factor comes down to your last frost date. Look into how long it takes for seedlings to develop before they need to be planted out. This will include the days it takes to germinate then the time it takes for them to reach their development point for planting out. Use that time to count back the weeks they need from your last frost date and that’s the earliest you can sow undercover.

Seed packets take this into account when they present information on when to sow. Know though that most seedlings, with optimal conditions, are ready to be planted outside about a month after they germinate. If you wait too long to plant them out, the plants and their harvests will likely be negatively impacted. With seed sowing, being patient with seed sowing pays dividends in the spring and summer.

The information above pertains to starting seeds indoors. If you’re wondering about direct-sowing in containers or the garden then it’s different. Sowing outdoors generally needs to be done after your last frost date and once the soil has warmed up. Sow before then and the seeds might not ever grow, or if they do, the emerging seedlings can be killed by cold and frost.

Average vs Safe Frost Dates

Below are the rough guides to the first and last frost dates for different zones in the northern hemisphere. To find the date more specific to your town or region search for them over here: USA & Canada and Britain. Please also be aware that these dates are all average dates and that in an average year they’re correct. Some years you’ll get freakish cold weather in spring though so talk to gardening friends and neighbors about your safe date too. For me, my average last frost date is March 31st. My safe date that I can count on for no more frost is a month later.

If I’m sowing hardy plants, like peas or cabbages, or veg that will be grown in the greenhouse, I’ll tend to stick to the average last frost date. For more tender outdoor grown plants I’ll use my safe date and grow them indoors. If you see “Plant after all danger of frost has passed” on the back of a seed packet, use the safe date, not the average. Plants sown a little later will catch up quickly and you’ll be surer that they’ll survive.

Zone	Average Last Frost Date	Average First Frost Date
1	July 16-31	August 1-15
2	June 8-21	September 8-21
3	May 8-21	September 21-October 7
4	May 22-June 7	October 1-15
5	May 1-15	October 8-21
6	April 16-30	October 16-31
7	April 1-15	October 21-November 7
8	March 16-31	November 1-15
9	February 16-28	December 1-15
10-13	No freeze	No freeze

Some Crops Benefit from an Early Start

There are plants that will benefit from an early start. If you have a warm conservatory or heated greenhouse then you could start off warm weather veg like tomatoes and eggplant (aubergines) relatively early. It’s important to give these indoor-grown seedlings the correct amount of light, warmth, and humidity so do read up on growing seeds indoors in winter. In many places grow lights are recommended if you are growing seedlings before the spring equinox. Especially tropical seedlings such as tomatoes, chilies, peppers, and eggplants.

Cooler weather veg is best sown in the early part of the year as well. These can deal with a lot less light and warmth and a windowsill can do. An unheated propagator is a good idea in getting these started though. The good news is this means that you can sow kale, cabbage, broccoli, brussels sprouts, and onion seeds undercover without expensive equipment or electricity bills. When they’re large enough, you can then transplant them in your garden after the last frost. Make sure to harden them off properly first and to give them the protection of fleece or a hoop tunnel. Here’s a general guide to when you can begin sowing vegetable seeds. Also, the links take you to where you can purchase the seeds from MIgardener. Use the code LOVELYGREENS to get 10% off your purchase.

Seeds to Sow Undercover up to 10 weeks before the last frost date

• Eggplant (aubergines) – on heat and with grow lights
• Chilis (spicy) – on heat and with grow lights

Seeds to Sow Undercover up to 8 weeks before last frost date

• Onion and shallot seeds
• Peppers (mild flavor) – on heat and with grow lights

Seeds to Sow Undercover 6 weeks before last frost date

• Fava beans (broad beans)
• Early brassica varieties: broccoli, cabbage, cauliflower, kale
• Kohlrabi
• Leafy herbs: cilantro (coriander), dill, parsley
• Lettuce
• Peas for shoots
• Radish
• Spinach
• Spring onions
• Turnips

Seeds to Sow Undercover 4 weeks before last frost date

• Same as for above plus
• Beets
• Garden peas

Seeds to Sow Undercover 2 weeks before last frost date

• Same as above plus
• Celeriac
• Celery
• Tomatoes – with warmth

More Winter Gardening Ideas

In late winter and very early spring, there’s a lot that we can busy ourselves with to get a head-start on the growing year. Here are more ideas that will help you grow a bountiful vegetable garden this year!

• How to Start a Vegetable Garden
• Winter Gardening Ideas and Projects
• February Garden Jobs for the Vegetable Garden
• Ways to to protect vegetables from cold weather