As the Ground Thaws in March, I Direct Sow These 12 Hardy Flower Seeds for a Head Start on Summer Color

I always feel a quiet sense of excitement at this point in March. The days are gradually getting longer, there’s a softness in the air, and even though it’s still a bit chilly, you can tell the season is beginning to shift.

The soil is usually my signal. When it’s no longer frozen solid and starts to crumble easily in your hand, I know it’s time to begin.

Many flowering plants make you wait until after your last frost date. It can feel like a long, drawn-out pause—checking the forecast, watching the calendar, and holding back just a little longer than you’d like. But not all flowers are so delicate.

Some are surprisingly resilient.

These are hardy annuals—plants that can tolerate cooler conditions and complete their entire life cycle within a single growing season. They’re naturally quick to germinate, eager to grow, and ready to flower as soon as they get the chance. Once they start, they don’t waste time.

I often take my cue from the garden itself. When I notice the first tiny weeds appearing along paths and borders, it’s a reliable sign that the soil has warmed enough for seeds to begin germinating. That’s usually when I start sowing.

Of course, there’s always a degree of uncertainty this early in the season. A sudden cold spell can affect young seedlings. But seeds are inexpensive and plentiful, so it’s easy enough to sow again if needed. Most of these plants can handle a light frost, and if colder weather is forecast, a simple layer of fleece overnight offers enough protection.

I also like to keep a small portion of seeds back and sow them again after my last frost date. That way, I get a second flush of flowers later in the summer. Still, it’s the early sowing that really makes the difference—by the time many gardens are just getting started, these are already growing strongly and beginning to bloom.

And that early start is something you really notice as the season unfolds.

Here are the 12 flower seeds I’ll be sowing this March.

1. Larkspur (Consolida ajacis)

Forget everything you know about delphiniums being divas. Larkspur is their country cousin—taller, tougher, and willing to grow from seed sown directly into cold mud. In zones 3-9, these will self-seed so reliably you’ll think they’re perennial, sending up 3-to-4-foot spires in shades of blue, pink, and white from late June through August.

I’m planting ‘Earl Grey’ this year—a silvery lavender that’s so refined it looks like it belongs in a Victorian conservatory. For something bolder, ‘Giant Imperial’ hits 4 feet with densely packed spires in true blue, rose, and white. They need that March chill to germinate properly; warm soil actually inhibits them, so don’t wait until April. Sow now while it’s still 50°F or below, barely cover the seeds with 1/8 inch of soil, and space them 6 inches apart.

They want full sun to partial shade and bloom heaviest in cool weather, often giving a second flush in September if you cut them back hard after the first round. Excellent for cutting—those hollow stems need searing in boiling water for 10 seconds to last in vases.

2. Orlaya (Orlaya grandiflora)

If Queen Anne’s Lace went to finishing school, it would come back as Orlaya. Hardy in zones 3-9, it grows 2-3 feet tall and keeps producing flat-topped umbels of pure white from June until frost, with each tiny flower framed by a delicate fringe that looks like lace edging.

The variety ‘White Lace’ is the standard, but hunt down ‘Minoan Lace’ for slightly larger, more substantial flower heads that stand up better to rain. Direct sow in March—they have taproots and hate being moved. They take their time germinating (sometimes 3 weeks in soil as cold as 45°F), so don’t panic when nothing happens immediately.

Space them 12 inches apart in full sun to light shade; they tolerate clay soil better than most delicate-looking plants. By late June, you’ll have those ethereal blooms that last 10 days in a vase, and if you leave the seed heads, they look like tiny stars all winter.

3. Bupleurum (Bupleurum rotundifolium)

This is the one that makes visitors stop and squint. Is it a flower? Is it a foliage plant? The answer is yes. ‘Green Gold’ produces chartreuse-yellow bracts that look like miniature eucalyptus leaves, surrounding tiny yellow-green true flowers. It’s a textural game-changer, hardy in zones 3-9, growing 2-3 feet tall with that loose, architectural branching that florists pay premium prices for.

Sow direct in March—it germinates best in soil that’s barely warmed past 45°F, which is exactly what you have right now. Space plants 10 inches apart in full sun; they tolerate poor soil and drought once established.

Blooms appear by early July and continue until frost without deadheading. The stems are incredibly strong and dry perfectly for winter arrangements, turning a soft straw color. If you’re growing for cutting, sow in succession every two weeks through April for continuous harvest.

4. Corn Cockle (Agrostemma githago)

A survivor from the wheat fields of old Europe, this one nearly vanished with modern agriculture but is having a moment in cottage gardens. Hardy annual in zones 3-8, it grows 3 feet tall with long, strong stems perfect for cutting.

‘Ocean Pearls’ gives you white petals speckled with delicate purple dots, looking like someone flicked a paintbrush at them. The straight species is that perfect velvety purple-pink that photographs almost black in evening light. Sow these directly where they stand in March, 1/4 inch deep, spacing 6 inches apart.

They don’t transplant well, and they actually prefer poor, sandy soil with sharp drainage—give them rich compost and they’ll grow huge and leafy with few flowers. Full sun is mandatory. They bloom from late June through August, and the seed pods look like little wizard hats if you leave them for dried arrangements.

5. Love-in-a-Mist (Nigella damascena)

Nigella is three plants in succession. First the bloom, floating in its haze of feathery foliage as though suspended rather than attached. Then the seedpod, striped and swelling and improbably beautiful, rattling faintly when the autumn wind finds it. Then the dried pod on a winter windowsill, still ornamental, still earning its keep. Few annuals work this hard across a season.

True hardy annuals in zones 2-11—literally anyone can grow these. Scatter the seeds in March where you want them, barely covering with 1/8 inch of soil; they germinate in the cold damp and actually prefer soil temperatures around 50-55°F.

Space 8 inches apart in full sun to partial shade—they bloom in light shade, just not as heavily. By late June, you’ll have those misty clouds of bloom atop 18-inch stems, followed by the most extraordinary inflated seed pods that look like alien balloon sculptures. They self-seed politely, never weedy, so you’ll have them forever once established. Blooms last 7-10 days in water.

6. Phacelia (Phacelia tanacetifolia)

Beekeepers know this one as “fiddleneck,” but gardeners are catching on. Hardy in zones 3-10, it grows rapidly to 2-3 feet, producing curved clusters of lavender-blue flowers that unfurl like a scorpion’s tail from June through August.

Sow direct in March, 1/4 inch deep, spacing 12 inches apart. It germinates in soil as cold as 40°F and handles partial shade better than most annuals—I’ve had success with morning sun and afternoon shade. The lacy, fern-like foliage is a nice textural addition to the border even before the blooms start.

The flowers are nectar magnets—honey bees, bumblebees, and mason bees go absolutely wild for it. It makes a great filler, bridging that gap between spring bulbs and summer perennials. If you dig it in before it sets seed, it adds serious organic matter to your soil, but if you let it go, it will self-seed for next year.

7. Flanders Poppy (Papaver rhoeas)

Not the Oriental poppies that sulk for years after transplanting—these are the annual field poppies that paint meadows red across Europe. Hardy in zones 3-9, these grow 2-3 feet tall and bloom from late May through July, sometimes giving a second flush in September if sheared.

‘Mother of Pearl’ is the stunner here: silvery-grey petals washed with pale mauve, soft pink, and lavender, all on one plant. For drama, try ‘Black Peony’—double, frilly blooms in the deepest burgundy-black.

They need light to germinate, so just scratch them into the soil surface in March—do not cover them. Space 6 inches apart in full sun; they hate root disturbance, so direct sow only.

They prefer poor, well-drained soil and will rot in heavy clay that stays wet. Blooms last only 3-4 days in a vase but are worth it for the color impact. Let some go to seed for next year’s volunteers.

8. Annual Pincushion Flower (Scabiosa atropurpurea)

Not the perennial blue scabiosa that melts in July heat—these are the old-fashioned cutting garden varieties that keep going until frost. Treat as a hardy annual in zones 3-9, growing 3 feet tall with long, wiry stems perfect for arrangements.

‘Black Knight’ is so dark it’s nearly chocolate-brown, with perfectly round pincushion centers that hummingbirds probe. ‘Salmon Queen’ gives you that vintage coral color. Sow direct in March, 1/8 inch deep, spacing 10 inches apart in full sun.

They handle light frosts without issue and prefer lean, well-drained soil—too much nitrogen gives you floppy stems. Blooms start in late June and continue until hard frost if you keep cutting. Unlike the perennial types, these don’t suddenly collapse with powdery mildew in August. Flowers last 7-10 days in water; sear the stem ends for best results.

9. Toadflax (Linaria maroccana)

Delicate spires of snapdragon-like flowers in the most outrageous color combinations. ‘Northern Lights’ mix gives you stems striped with magenta, yellow, peach, and violet all on the same plant. Hardy annual in zones 3-9, growing 18-24 inches tall.

Sow direct in March, barely covering the dust-like seeds with 1/16 inch of soil. They germinate in cold soil and bloom by early June, continuing until frost. Space 8 inches apart in full sun to partial shade—they’re one of the few annuals that actually bloom well with only 4-5 hours of direct sun.

Perfect for the front of the border, weaving between taller plants. The foliage is narrow and grassy, so they don’t hog visual space until those psychedelic flower spikes shoot up. Deadhead for continuous bloom, or let them self-seed for a patchwork effect next year.

10. Bishop’s Flower (Ammi majus)

Queen Anne’s Lace refined—lacy, flat-topped white umbels that add that essential “cloud” effect to arrangements, but without the weediness. Hardy in zones 3-9, it grows 3-4 feet tall with strong, straight stems that don’t flop in rain.

Direct sow in March; it needs 90 days to bloom, so early planting is essential for June flowers. ‘Graceland’ is a compact variety at 24 inches, perfect for smaller gardens.

Sow 1/4 inch deep, spacing 12 inches apart in full sun to very light shade. They prefer average soil and moderate moisture—too dry and they’ll bolt to seed too quickly. The trick is succession sowing—plant some now, some in April—for continuous clouds of white all summer. It dries beautifully too, turning a soft ecru color. Blooms last 10-12 days in fresh arrangements.

11. Pot Marigold (Calendula officinalis)

Not the flat, boring orange bedding plants—modern calendulas have come a long way. Hardy in zones 3-9, these grow 18-24 inches tall and 12 inches wide, blooming from late May until hard frost.

‘Indian Prince’ has mahogany backs to the petals that show when the flowers are half-closed, giving a two-tone effect of burnt orange and rust. ‘Sherbet Fizz’ is pale peach with dusty rose tips. Sow direct in March, 1/4 inch deep, spacing 8 inches apart.

They germinate in soil as cold as 40°F and prefer full sun. Deadheading is essential—if you let them go to seed, they’ll stop blooming.

The petals are edible, adding color to salads, and they have that herbal, resinous scent. Cut flowers last 5-7 days; harvest when the petals are fully open but before the center turns brown.

12. Mignonette (Reseda odorata)

This is the one you grow for scent, not looks. The flowers are small, spiky, and greenish-white—nothing to write home about visually. But the fragrance? Pure heaven. Warm, honeyed, slightly spicy, it fills the evening garden from June through September.

Hardy annual in zones 3-9, growing 12-18 inches tall and 8 inches wide. Sow direct in March, barely covering the seeds—they need light to germinate.

Space 6 inches apart in full sun; they prefer cool conditions and will bloom by June, though they often pause in the heat of July and resume when temperatures drop in August.

‘Machet’ is the classic variety with the strongest scent. Plant it near paths or seating areas where you can appreciate the fragrance in the evening. The stems are too short for tall arrangements but perfect for small posies that scent an entire room.