Winter Sowing Cosmos: A Simple Way to Get an Early Start on Blooms

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As a flowering annual cosmos brings vibrant color to summer gardens with its bright cheerful blooms. While cosmos can be directly sown in the garden after the last spring frost, starting the seeds in winter via winter sowing allows the plants to get a head start on growing. This means you can enjoy cosmos flowers much earlier in the season.

Winter sowing is an easy, low-cost way to germinate cosmos and many other plants during the colder months. With just a few basic supplies, proper timing, and the right conditions, winter sowing cosmos can help provide an abundance of blooms in your garden by mid-summer.

What is Winter Sowing?

Winter sowing, also called winter seed sowing, is the process of sowing seeds outdoors in winter. It takes advantage of natural winter conditions to naturally stratify seeds and promote earlier spring germination.

The basic winter sowing method involves sowing seeds in containers left outside throughout the winter months. The containers protect the seeds from animals and severe cold while still exposing them to the moist, cold conditions that naturally occur in winter.

This cold moist stratification helps break seed dormancy, resulting in earlier and often higher germination rates once warmer spring weather arrives. It’s an easy, passive way to get a head start on the growing season.

Can You Winter Sow Cosmos?

Yes, cosmos is well-suited for winter sowing. As a hardy annual, cosmos seeds can withstand cold winter temperatures and light frost. And starting them in winter helps the plants bloom earlier and grow stronger by the summer.

Some tips for successful winter sowing of cosmos:

  • Choose appropriate cosmos varieties suited for your growing zone. Look for ones noted for early flowering.

  • Start the winter sowing process in late winter or early spring for your zone.

  • Use containers with drainage holes and a seed starting or multipurpose potting mix.

  • Sow seeds shallowly, about 1⁄8 inch deep and lightly cover with soil or potting mix.

  • Water sparingly over winter, taking care not to saturate or drown seeds.

  • Provide protection from excessive cold but still expose to outdoor winter temperatures.

  • Transplant seedlings after last frost date once they’ve grown their second set of true leaves.

Best Practices for Winter Sowing Cosmos

Follow these best practices when winter sowing cosmos for the best results:

Choose the Right Variety

  • Select cosmos varieties suitable for your USDA planting zone.

  • Look for early blooming varieties bred for cooler conditions.

  • Dwarf cosmos varieties work well for containers. Taller ones may require staking.

Use Quality Seed Starting Mix

  • Use a sterile, soilless mix to prevent damping off disease.

  • Multi-purpose and seed starting mixes both work well.

  • Ensure the mix drains well but still retains moisture.

Sow Seeds Shallowly

  • Sow cosmos seeds just 1⁄8 inch deep in containers.

  • Gently press seeds into soil contact but don’t bury them too deep.

Water Sparingly Over Winter

  • Water just enough to keep soil slightly moist, not saturated.

  • Plastic dome lids help retain moisture while allowing airflow.

  • Lift domes periodically to prevent excess moisture buildup.

Shelter Containers from Severe Cold

  • Place containers in a cold frame or unheated garage or porch.

  • Avoid exposing seeds to temperatures below 25°F (-4°C) for extended periods.

  • Insulate containers with straw or bubble wrap if needed.

Allow Natural Stratification to Occur

  • Let seeds undergo natural moist chilling for 8-12 weeks for best germination rates.

  • Begin process in late winter depending on your climate.

  • Bring containers indoors if temperatures rise too early.

Transplant After Last Frost

  • Transplant cosmos outdoors after all danger of frost has passed.

  • Harden off seedlings first by gradually exposing them to outdoor conditions over 7-10 days.

Step-by-Step Guide to Winter Sowing Cosmos

Follow these simple steps for winter sowing cosmos:

Gather Needed Supplies

  • Seed starting mix
  • Containers with drainage holes – yogurt cups, jars, pots, etc.
  • Cosmos seeds
  • Small scoop, spoon, or stick for sowing seeds
  • Clear plastic dome lids or plastic wrap
  • Spray bottle for watering
  • Optional: straw, bubble wrap for insulation

Prepare Containers

  • Fill containers nearly to the top with moistened seed starting mix.

  • Lightly firm the mix but don’t pack it down too much.

Sow Seeds

  • Sow 2-3 cosmos seeds per cell, about 1⁄8 inch deep.

  • Gently press seeds into the mix and cover lightly with more mix.

Water Sparingly

  • Mist soil lightly until moist but not saturated.

  • Place dome lids over containers to retain moisture.

Shelter Outdoors

  • Set containers in a sheltered, sunny spot like a porch or cold frame.

  • Insulate with straw or bubble wrap if needed during extreme cold.

Allow Natural Stratification

  • Leave containers undisturbed for 8-12 weeks, allowing natural winter conditions to stratify seeds.

Transplant Seedlings

  • Carefully transplant seedlings after hardening off for 7-10 days once frost danger has passed.

Enjoy Early Blooms!

  • Water and care for transplants and enjoy cosmos blooms much earlier than sowing after last frost!

With the right timing and care, winter sowing is a simple way to get a head start on growing cosmos from seed. The extra time lets the plants establish earlier for better growth and earlier blooms to enjoy all season long.

Other Flowers You Can Winter Sow

In addition to cosmos, here are some other flowering annuals and perennials well-suited for winter sowing:

  • Snapdragons
  • Poppies
  • Calendula
  • Bachelor buttons
  • Sweet peas
  • Marigolds
  • Zinnias
  • Petunias
  • Hardy perennials like lavender, salvia, daisies

The key is choosing cold-tolerant varieties that can withstand frost. Check seed packets for suitable sowing times and directions. With the right flowers, winter sowing makes starting a flower garden easy.

Enjoy Earlier Blooms Through Winter Sowing

By exposing seeds to natural winter conditions, winter sowing cosmos and other flowers allows earlier spring germination for healthier, more vigorous plants. This translates to earlier and longer-lasting blooms in your garden.

If you’re eager to get growing as soon as winter ends, winter sowing is an easy and effective way to get a head start on your backyard flower garden. The extra time pays off with hardier transplants and gorgeous blooms you’ll enjoy all season long.

Perennials and Hardy Annuals

As a general rule, you can plant a plant’s seed any time in the winter, no matter what the weather is like outside. Sprouting will occur when warmth arrives, normally in spring. However, the seed can also sprout during some freak warm spell between weeks of frigid conditions. This is not a problem for perennials and hardy annuals. They simply yawn in the face of frost.

How to Winter Sow Cosmos | Perennial Garden

FAQ

Can you plant cosmos seeds in winter?

Cosmos can be direct-seeded in the garden in early spring once all threat of frost has passed (mid-March here in North Texas). But you can also start seed indoors in late January or early February and set out as tranplants. This gives your plants a head start.

Can you winter sow zinnias?

Winter sowing also doesn’t need to stop with cold weather, either: many people use this technique well into spring to get a head start on heat-loving crops like cucumbers or zinnias.

How late can you sow cosmos seeds?

Sow cosmos seeds undercover in March-April, or direct sow in May. Plant out seedlings once the frosts have passed in late May or June.

What seeds can be winter sowed?

Some edible options for winter sowing include the classic cool-season crops – like broccoli, cauliflower and cabbage. Leafy greens – like lettuce, kale and bok choy – are also hardy annual options. Herbs like sage, oregano, dill, and mint are good winter sowing candidates too.

Can Cosmo seeds be planted in winter?

Winter sow in containers for perfectly hardened off cosmo seedlings large enough to transplant once the ground can be worked. You can also try direct sowing these in the fall. Cosmos are one of the easiest seeds to sow directly. 11. Stock Winter-sow stock seeds in January for fragrant blooms with varied color options.

Will Cosmos grow if left outside?

Cosmos is an annual. If left outside in frosty temperatures, they will die. However, at the end of the growing season, if you allow the dead flower heads to drop their seeds, cosmos seeds will go dormant and sprout when the soil warms up again in the spring.

Is winter sowing suitable for me?

If you’re looking for a gardening method that doesn’t require a greenhouse or indoor space, then winter sowing is suitable for you. Winter Sowing is a process whereby you create mini greenhouses using translucent plastic containers. Once the seeds are sown, these little greenhouses are placed outdoors in the elements and then we let nature take its course.

Are Cosmos easy to grow?

Yes cosmos are easy to grow. ‘Cosmos is one of the easiest flowers to grow from seed that is directly sown in the garden bed,’ advise the experts at American Meadows. ‘As they grow, stake cosmos if necessary, and water them regularly,’ says Sarah Raven. Cosmos suffer from few pest problems.

Can you grow cosmos from seed?

Cosmos bipinnatus, the most commonly grown, also known as Mexican aster, originates from the Americas. When it comes to growing cosmos from seed you have two options. You can grow them in modules or seed trays indoors, or plant them directly out in the garden. There are benefits to both. How do you successfully grow cosmos?

Does a cosmos flower in the fall?

Cosmos can be slower to germinate, but it then blooms quickly and continues to flower through the fall. The flowers top long slender stems and form a cloud of color all summer that attracts bees, butterflies, and birds to your garden. Cosmos flowers look a lot like daisies.

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