What Vegetable & Herb Seeds To Start Indoors In May

If you’re still looking to do some indoor seed starting come May, this is the post for you! Usually by May, most Northern gardeners are focused on outdoor gardening, but there are still a few vegetable & herb seeds you can start indoors. Really, the seed starting never ends!

If you’ve stumbled upon this blog and it’s not currently the month of May, be sure to check out my other monthly seed starting posts so you know exactly what seeds you should be starting now.

• 50+ Seeds To Start In April
• 20 Seeds To Start In March In The Canadian Prairies
• 8 Seeds To Start Indoors In February
• 15 Seeds To Start Indoors In January In Zone 3

So what vegetables and herbs can you start indoors in May?

Before I get to that, please note this post is intended for gardeners in Zone 3-5. This means your last frost date is likely anywhere from May 15-June 5.

Your last frost date is important to know as you should plan all your seed starting by working back from that date.

For example, my average last frost date here in Manitoba in Zone 3b is typically between May 27-June 1. This means on January 1st, there’s approx. 150 days until my seedlings can head into the garden. I determine when to start each seed based on the days to maturity labelled on the back of each seed packet.

Hope this provides some clarity! You can find even more info on local frost dates on the From Soil to Soul blog.

Throughout this post, I’ve linked some of my fav seed varieties from my preferred organic seed provider, West Coast Seeds. When you place your seed order through WCS, I earn a small commission, which allows me to continue creating free content for you here. Thank-you for your support!

Now let’s get to it so you can start your May seeds indoors!

10 Veggie & Herb Seeds To Start Indoors In May

*Disclaimer*

This post may contain affiliate links to products for your convenience. From Soil to Soul gains a small commission from purchases made through those links, at no additional cost to you.

5 Vegetables To Start Indoors In May

1. Summer Squash/Zucchini

Start your zucchini and summer squash seeds indoors anywhere from 2-4 weeks before your last frost date.

You can certainly direct sow summer squash seeds in the garden after your last frost date. But I suggest starting inside as it will give you an earlier harvest. Plus it makes watering/fertilizing easier as you’ll know exactly where your seedling is planted in the garden.

Summer squash and zucchini are maybe one of the easiest veggies to grow for beginners. And you’ll be harvesting from them for most of the season. There’s so much to love, and so many different varieties to choose from.

Here’s a few of my fav I grow every year without fail.

The Best Organic Summer Squash/Zucchini Varieties

• Desert Green Zucchini — pictured above, perfectly uniform fruits
• Goldy Yellow Zucchini — produces all season long
• Sunburst Pattypan — scallopini variety that looks like small, yellow jewels

2. Winter Squash

Start your winter squash seeds indoors anywhere from 2-4 weeks before your last frost date.

You want to be sure any risk of frost is gone before transplanting in the garden as squash are tender annual plants that will easily be killed off in the cold. I usually wait until the first week of June to transplant my winter squash. Harvest doesn’t occur until Fall anyway, so they have a long time to grow and mature.

Most winter squash varieties become very big and bushy. Some of my squash plants develop vines well over 10ft long that cover the soil entirely. So be sure to give your plants lots of space to grow and spread out.

I suggest spacing out your winter squash to have anywhere from 1-2ft between each seedling.

The Best Organic Winter Squash Varieties

• Delicata — a mild tasting, stripped squash that grows really well in most cold regions
• Mashed Potatoes Acorn Squash — a small, white squash that looks like mashed potatoes when cooked
• Early Butternut Squash — produces fruit faster than most other butternut squashes, you should be able to harvest in 3 months or less

3. Pumpkins

Pumpkins are another veggie that benefit from being started late so that they don’t have to stay inside for too long. Seedlings will germinate very quickly (in as little as 3-5 days) and the foliage will start to sprawl shortly after.

Some years, I wait until 1-2 weeks before my last frost date to start my pumpkin seeds indoors. And this has worked just fine!

Similar to winter squash, pumpkins are delicate, tender annuals that should be planted in the garden well after any risk of frost is gone. Depending on the variety, pumpkin vines will also get massive! Try growing them up a trellis or archway to maximize the space in your garden.

The Best Organic Pumpkin Varieties

• Rouge Vif d’Etampes Heirloom Pumpkin — a gorgeous heirloom variety that gives Cinderella vibes
• Jack Be Little Mini Pumpkin — a mini variety that is compact and ideal for small or urban gardens
• Dill’s Atlantic Giant Pumpkin — a giant variety that can actually get up to 1,000lbs or more

4. Cucumbers

Cucumbers are also fast growing veggies that can be started indoors anywhere from 2-4 weeks before your last frost date. I aim to start my cucumbers indoors during the first week of May so that they’re inside for no longer than 20-25 days before heading into the garden.

If you’re planning to grow cucumbers in a greenhouse, you can start them a few weeks earlier as they’ll go outdoors earlier too. If you do have a greenhouse, try growing a parthenocarpic variety of cucumber. They are seedless and don’t require fertilization, which means you’ll still get tons of fruit even when grown indoors.

The Best Organic Cucumber Varieties

• Roxynante Slicer — a really productive variety that can actually withstand some cold temps, so will produce into Fall
• Marketmore Slicer — my most trusted cucumber variety, the plants produce dozens and dozens of fruit
• Excelsior Pickling — the best cucumber for pickling, hands down

5. Melons

Finally, melons are a great seed to start indoors in May. Start them anywhere from 2-3 weeks before your last frost. 

The same tips apply to melons as mentioned for winter squash and pumpkins. They will grow quickly so avoid starting them too early. The first week of May is ideal for Zone 3 gardeners.

The Best Organic Melon Varieties

• Yellow Doll Watermelon — small, stripped melon with yellow fruit that is sooo tasty
• Black Beauty Mini Watermelon — A compact variety that is great for small or urban gardens
• Halona Cantaloupe — a disease resistant variety that is surprisingly tasty

5 Herbs To Start Indoors In May

1. Basil

You can really start basil seeds indoors at any time between March-May. Basil is a great herb to succession plant, meaning you can start seeds every few weeks in order to be harvesting for more of the growing season.

I like starting my basil seeds in May because they grow extremely quickly under both grow lights or natural light.

Plus, starting basil in May eliminates the need to “pot up” my seedlings. I don’t need to size up their growing space before they’re ready to go in the garden. It’s a win-win!

You can also direct sow basil in your garden after your last frost date.

The Best Organic Basil Varieties

• Dolly Basil — I will never stray away from this one, it’s highly productive all summer long
• Rosie Purple Basil — my fav purple basil variety
• Emerald Tower — go check out the photos to believe it, a basil that truly creates a tower of green

2. Borage

I’m a borage advocate because I don’t believe it gets the love it deserves! Borage is a gorgeous herb with both edible foliage and flowers. I love freezing the flowers into ice cubes for summer cocktails.

The plants get big and bushy in the garden and will attract dozens of pollinators.

Start your borage indoors anytime between the last week of April and first week of May. Or 3-4 weeks before your last frost date.

Many years I’ve ran out of time and just direct sow’d my borage, which also works great. Borage also tends to reseed itself in the Fall, so you will likely notice seedlings popping up in the Spring.

The Best Organic Borage Varieties

• Classic Borage — the leaves are large, fuzzy and cucumber scented while the flowers are delicate and sweet

3. Cilantro

Cilantro is an easy-to-grow and fast maturing herb. Most gardeners direct sow cilantro in early Spring, but you can also start indoors and transplant out anytime in May before your last frost date. Cilantro is cold tolerant and doesn’t mind a little frost!

Linked below is my go-to cilantro variety that I grow every year and LOVE. I also sow a late crop of cilantro at the end of August, which provides us a nice harvest throughout the Fall.

The Best Organic Cilantro Varieties

• Santo Cilantro — a variety that can withstand heat without bolting, love it

4. Dill

Dill is another herb you can either start indoors or direct sow after your last frost. I like to do both! Primarily because I find transplanting seedlings helps me organize my garden better.

This approach will also provide you successions of dill to harvest throughout the season. This is a great idea if you’re someone who enjoys pickling as well as eating dill fresh. Dill also freezes really well so the more the merrier in my opinion!

If starting your dill indoors, start seeds 2-3 weeks before your last frost date.

The Best Organic Dill Varieties

• Ella — a compact variety that does well in a container or in the garden
• Bouquet — the perfect dill for pickling

5. Summer Savory

Savory is a herb I forget to grow in my garden but so many gardeners adore it, so it’s making its way onto this list of herbs to start in May.

There are two types of savory;

• Winter Savory — can be a perennial in Zone 3 or warmer
• Summer Savory — annual herb

Summer savory does best when started indoors about 4 weeks before your last frost date. Whereas winter savory needs to be started indoors much earlier.

With summer savory, the seeds are very tiny and do take about 2 weeks to germinate, so be patient!

The Best Organic Summer Savory Varieties

• Classic Savory — grows really quickly and has an amazing aroma

And there you have it! Those are 10 veggies and herbs to start indoors in May.

I hope this kicks off your May seed starting!

Remember, these are seedlings that do best when they spend less time indoors. So wait until 2-4 weeks before your last frost date to start these seeds.

More Organic Gardening Blog Posts

• How I Plan Out My Zone 3 Veggie Garden
• When To Add And How Much Worm Castings To Use In Your Veggie Garden
• Complete Raised Bed Gardening Guide For Beginners
• Straw Mulch In The Veggie Garden — How-To & Benefits

If you have any unanswered questions about seed starting, be sure to comment below. I love hearing from you and answer all comments.

You can follow @fromsoiltosoul on Instagram and Pinterest for more organic gardening content too.