Asters are a classic late summer and fall blooming flower that are beloved for their colorful daisy-like blooms. Growing asters from seeds is an easy, thrifty way to add jewel-toned color to flower beds borders and containers. This complete guide will walk you through everything you need to know about sowing transplanting and caring for vibrant asters grown from seed.
A Brief Overview of Asters
Asters belong to the large Asteraceae plant family which includes other familiar flowers like sunflowers, zinnias, dahlias and chrysanthemums There are over 180 different aster species suited to various climates and growing conditions
Popular garden types include
- New England Aster – Vibrant pink, purple or white flowers on bushy 1-4 ft. plants.
- Michaelmas Daisy – Classic fall-blooming aster with blue, lavender or white flowers. Grows 1-3 ft. tall.
- Alpine Aster – Low-growing 4-12 inch plants with flowers in blue, pink or white.
- Stokes’ Aster – Heat-tolerant asters with blue or white 2-3 inch wide blooms.
When to Start Aster Seeds
Timing is important when starting asters from seed. Follow these guidelines:
- Start seeds indoors 6-8 weeks before your last expected spring frost date.
- Use a seed starting mix and provide 65°F – 70°F soil temperatures for germination.
- After sprouting, grow seedlings on at 60°F – 65°F with ample light.
- Harden off and transplant outdoors after all danger of frost has passed.
You can also direct sow seeds outdoors about 2 weeks before the last frost date.
How to Plant Aster Seeds
Planting aster seeds is easy whether starting indoors or sowing directly outside. Follow these simple steps:
Indoors
- Fill starter trays or pots with moist seed starting mix. Press seeds into the surface.
- Cover seeds lightly with 1/8′′ of mix. Keep evenly moist but not saturated.
- Expect sprouting in 7-21 days. Provide ample light once seedlings emerge.
- Transplant outdoors at 6-8 weeks when hardened off, spacing 12′′ apart.
Outdoors
- Prepare a planting bed in full sun with compost or organic matter worked in.
- Press seeds onto the surface of warm, moist soil. Cover with 1/8′′ of fine soil or compost.
- Water gently to avoid washing away seeds. Keep soil moist but not soggy.
- Thin or transplant seedlings 12′′ apart when they reach 2-4 true leaves.
Caring for Asters Grown from Seed
With proper care, your asters will thrive once established:
- Water asters 1-2′′ per week. Add mulch to conserve moisture.
- Pinch back tips of young plants to encourage bushy, compact growth.
- Stake taller asters to prevent toppling, especially after rain or wind.
- Deadhead spent blooms to extend flowering into fall. Stop deadheading by early fall.
- Monitor for common pests like leafhoppers, Japanese beetles, slugs and snails.
- Divide congested clumps every 2-3 years in early spring as needed.
- Cut back dead growth in late fall and apply compost around the base of plants.
Tips for Success Growing Asters from Seeds
Follow these useful tips for the best results with starting asters from seed:
- Purchase fresh seeds each year for optimal viability. Store unused seeds properly.
- Give seedlings 14-16 hours under grow lights or in bright sunny windows.
- Prevent leggy, weak seedlings by providing good air circulation.
- Harden off transplants gradually over 7-10 days before planting out.
- Water new transplants consistently until they establish deep roots.
- Mulch to keep soil moist and reduce competition from weeds.
- Deadhead to prolong blooms. Leave last flowers to go to seed.
- Rotate aster planting spots each year to prevent disease buildup.
Recommended Aster Varieties for Seeds
Some top-performing asters to try from seed:
- King Asters – Extra large, long-blooming daisy flowers on 2-3′ plants.
- Matsumoto Asters – Compact mounded plants with abundant blooms in mixes or solids.
- Monte Cassino Asters – Floriferous, mildew-resistant plants with 5′′ blooms.
- New England Asters – Classic, cold-hardy asters reaching 3-4′ tall.
- Wood’s Pink Asters – Vibrant hot pink flowers on compact, early plants.
- Alpine Asters – Dwarf plants under 1′ tall perfect for rock gardens and edging.
Growing vibrant asters from seeds is easy and rewarding with proper timing and care. Follow the steps in this guide for success sowing seeds indoors or out. Soon you’ll have cheerful, colorful asters gracing your garden from late summer into fall.
Where to Plant Aster Seeds
If direct sowing outdoors, plant in moist, nutrient dense, well-draining soils that are exposed to at least four to eight hours of full sun each day. Do not plant asters in areas where the soil retains water, or alternately, where it readily dries out. Prepare the planting site by mixing in a source of organic matter like compost, or composted manure.
If starting indoors, use a seed starting soil mixture and cover the seeds lightly with ⅛ of soil. Water the seeds at planting time and keep them evenly moist until seedlings emerge after one to three weeks, depending on the variety. Harden off the seedlings and transplant out into the garden once danger of frost has passed. Read more about how to harden off seedlings here.
When to Plant Aster Seeds
Plant outdoors after the last frost of the season or start indoors six to eight weeks before the last frost date.
How to Plant and Grow Asters from Seed
FAQ
Are asters easy to grow from seed?
What makes these plants so great is that they can be grown from seed, are easy to grow, and flower at a time when the garden is starting to fade. As the day length shortens, this group of plants is prompted to begin flowering.
Does aster come back every year?
are asters annuals or perennials? Asters are perennial and if they’re planted in a sunny spot in free-draining soil they will return year after year.
How do you direct sow aster seeds?
When sowing outdoors, spread the seeds across the surface of moistened soil. Repeat this several times every 10 to 14 days and keep the soil moistened to ensure an extended blooming season. Thin seedlings out every six to eight inches once they emerge.
Do asters need heat to germinate?
Providing Optimal Conditions: Place the containers in a warm, well-lit area. Aster seeds typically germinate best at temperatures between 70-75°F (21-24°C). If you’re using artificial grow lights, keep them on for about 12-16 hours a day.
Can you grow asters from seed?
This also allows you to cover the lower foliage—which can get scraggly—with other perennials in the foreground, such as sedum, heuchera, or perennial geraniums. You can grow asters from seed, but it will take several years before the plants mature enough to bloom. If you’d like quicker results, opt for plants purchased from reputable nurseries.
How do you plant asters?
Select a sunny spot with well-drained soil. Asters thrive in sites receiving full sun to partial shade. The soil can be rich or of average quality, but it must be capable of draining well. Avoid planting asters in heavy clay soils since these tend to drain poorly.
How do you propagate asters?
The easiest way to propagate asters is to divide plants as they become too large for a planting area. Dig up the entire clump in early spring when they first appear, divide into sections and replant immediately. You can also simply cut some plants off the edge of a section using a shovel—just make sure to get the roots.