Do cosmos reseed themselves

How to plant and grow cosmos

Even if you only have a tiny garden – or just some pots – you have to grow at least one cosmos. They are the lowest maintenance, floweriest plants in the world.

Planting

From Seed

The seeds are long and thin, so can be easily handled, and can be planted into modules or jiffys. Sow under cover March-April at about 3mm deep in good compost. Water in well and place in a greenhouse or warm windowsill to help germination.

In the garden

Plant out after the risk of frost has past, plant out in your garden into soil that has been improved with manure or garden compost. Pinch out the growing tip of each stem when transplanting to encourage stems to branch and produce more cosmos flowers. Plant the cosmos in full sun and water well, then add a mulch to help conserve moisture. Stake and tie plants if necessary during the growing season and don’t forget to water regularly.

For Containers

The shorter varieties e.g. Cosmos Sonata and Antiquity are perfect for pots. Plant the seedlings 10in apart, keep them well watered and they’ll be in flower by early July and, if deadheaded, flower reliably until October.

Aftercare

Cosmos will flower till the first frosts if you regularly dead head and feed the plants. When dead-heading cosmos the trick is to cut the stem right back to the first leaf below, rather than just taking the flower head off (see Sarah’s video for a close-up guide on how to do this).

Cut flowers

Last 7-10 days, no conditioning needed. Pick fresh straight into water, just as the buds are about to bloom, and do not pick in the heat of the day. Deadhead the main blooms that are drooping and going over after about a week. Place out of direct sunlight.

You may also like:

  • Cosmos summer flower arrangement (Video)
  • How to sow, grow and stake cosmos (Video)

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All About Cosmos

Can I Grow Cosmos?

Cosmos are prized for their abundant, silky, daisylike flowers and their unflappable, easy-care nature in the garden. While bedding plants are sold in spring, cosmos are simple and inexpensive to grow from seeds. Plant them in full sun (in very hot regions, cosmos can take afternoon shade) and give them protection from strong winds. Cosmos tolerates a wide range of soil types, including poor soil. Plants need even moisture to get started, but mature cosmos are drought tolerant; plants produce more and larger flowers, however, if they are watered regularly.

What is the History of Cosmos Flower

Cosmos, in its annual form, is a native of Mexico. Along with taking gold, silver, and other riches from Mexico, 16th-century Spanish explorers sent hundreds of cosmos back to Madrid. Cosmos wasn’t collected until the late 1700s, however, and the flower made its way to England in 1789, thanks to the Marchioness of Bute, wife of the English ambassador to Spain.

It was at least another 50 years until cosmos got to the United States, indirectly from England and Spain and more directly from Mexico. This late start in British and American gardens probably accounts for the plant having no widely used common name, answering instead to its genus name, Cosmos, which comes from the Greek word kosmos, meaning “beautiful.” Cosmos is a member of the aster family.

Should I Grow Cosmos Seeds or Plants?

Either sow cosmos seeds outdoors after danger of frost has passed, or for an early start on summer blooms, sow seeds indoors four to five weeks before the last spring-frost date. Plant cosmos in full sun and protect them from strong winds. Space plants approximately 2 feet apart; with tall cosmos, space plants closer than the recommended 2 feet and let them support each other. Both germination and growth are fast, but cosmos plants are frost tender, so don’t be in a rush. Cosmos are light sensitive and don’t bloom their best until late summer, when the days grow shorter.

How Do I Cultivate Cosmos Flower Plants?

Move these heat-loving annuals to the garden after danger of frost has passed and the soil has warmed. Cosmos need light soil with average to poor fertility that has a neutral or slightly alkaline pH and is well-drained. Soil that is too rich yields weak-stemmed, sparsely flowered plants that bloom late and flop over, so avoid soil that has been heavily amended, and don’t feed the plants. Tall cosmos sometimes require staking to prevent their thick, hollow stems from breaking due to heavy rain or wind. Instead of staking, a gardener may also space plants closer than the recommended 2 feet and have the plants support each other.

Growing Tips

Pinch off spent flowers to encourage continuous bloom. Pinching stem tips can reduce height and encourage branching but isn’t necessary. Deadheading is recommended since it lengthens the bloom season. Cosmos plants that aren’t deadheaded will self-sow in warm regions. Typical plant height for cosmos is 1 to 5 feet.

What Insects & Diseases Affect Cosmos Flowers?

Unlike many garden plants, pests and diseases rarely affect cosmos. This makes it much easier for gardeners to grow.

Harvest Tips

Harvest once cosmos plants start to blossom.

Uses & Storage

Cosmos are traditional cottage garden plants and perfect for all types of informal plantings. Use taller plants in the back of the border and to fill in around bunches of perennials such as lilies, irises, and ornamental grasses. They’re also stunning combined with annuals, such as cleome, and tender perennials like cannas and dahlias. Smaller or dwarf plants are ideal near the front of the border, in containers, or as edgings. You can also use cosmos as a fast-growing annual hedge or in a cutting garden; these plants make outstanding cut flowers, and all cosmos attract butterflies.

Shop all Cosmos

Look for dwarfs, various flower colors and plant heights.

‘Cosmic’ Series: Short (1’ tall) plants with colorful yellow or orange flowers. Very reliable bloomer.

‘Sonata’ Series: large flowers in shades of pink, white and red on short, 1 to 2’ tall dwarf plants. Does very well in full sun, and flowers abundantly.

‘Candy Stripe Mix’: white flowers striped along the length of the petals with shades of red.

‘Daydream’: pale pink petals deepend to dark pink towards the tufted yellow center of the flower. Very striking.

‘Gazebo Mix’: white pink and red flowers are larger than most Cosmos and showy on 3 to 4’ tall plants.

‘Seashells Mix’: trumpet-like flower petals are rolled into tubes. Flowers in shades of pink, red and white. Plants grow 3′ tall.

‘Sensation’ Series: very large (4 to 6′) flowers in a variety of shades of pink, white and red. Plants grow to 4’ tall.

‘Versailles’ Series: excellent for cut flowers because of its wiry stems and large, colorful blooms in shades of red, white and pink. Blooms during short days, and thus is a good winter greenhouse cutflower plant.

‘Picotee’ attractive white flowers have reddish pink edges with faint red lines running the length of the petals and yellow flower centers.

Top 10 self-seeding plants for a low maintenance cottage garden

We all like to get free plants. And self-seeders produce new plants for us every year. They are ideal if you want a fuss-free garden, because they require little intervention. Left to bloom and set seed, these prolific varieties will soon fill every available patch in the garden.

Here are my top 10 self-seeding plants.

1 Papaver rhoeas

Also known as the common poppy, this is just as famous for its seeds as its red flowers. It likes full sun but will grow in most soil types. But it can spread dramatically, so don’t plant it near farmland or protected spaces.

2 Aquilegia

This is a cottage garden favourite that freely disperses its seeds, meaning new plants pop up all over the place. Often the next generation flowers a different colour to the parent plant.

3 Angelica archangelica

This is a beautiful architectural plant for any garden style. Thick stems branch out like fireworks, each one bearing a globe of tiny white flowers. It’s perfect for pollinators too.

4 Digitalis purpurea

The foxglove is immensely popular in British gardens, and one of the only tall flowering plants that thrives in the shade. Let it go to seed and new flower spires will brighten the garden every year.

5 Myostis sylvatica (forget-me-not)

A low-growing variety with delicate blue flowers that look stunning at the front of borders. It flowers in spring and spreads out like a carpet, making it ideal for rockeries and filling cracks in paving.

6 Verbena bonariensis

Tiny purple flowers bloom all summer on tall stems. Verbena adds height and structure to beds and is loved by pollinators. Leave it to its own devices and it will self-seed and pop up all over the garden.

7 Eryngium giganteum

Sea holly is a stunning architectural plant with silvery bracts and egg-shaped heads with delicate blue flowers. It is hardy and will grow happily in full sun and poor soil.

8 Foeniculum vulgare ‘Giant bronze’

Let this bronze fennel herb go to seed and it will reward you with more plants the following year. It has pretty yellow flowers and dark leaves. Plant in full sun in moist, well-drained soil for best results.

9 Lunaria Annua (honesty)

Honesty is renowned for its translucent disc-shaped seed pods that look just as good in a vase as the border. It produces pink, purple or white flowers in summer and its pearlescent seed pods spread freely.

10 Chrysanthemum parthenium

Also known as feverfew, this is a bushy perennial with pretty daisy-like flowers and fragrant leaves. It is low-growing and forms a nice carpet for the front of borders. Plant in full sun for the best flowers.

Sometimes, self-sown plants pop up in unwanted places, but it’s easy to transplant them to a better spot. Dig up the seedling with a trowel, taking care not to disturb the roots. Replant to the same depth in prepared soil and water well.

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Thursday – February 11, 2010

From: New Braunfels, TX
Region: Southwest
Topic: Wildflowers
Title: Will my wildflower seeds reseed by themselves?
Answered by: Jackie OKeefe

QUESTION:

I have planted wildflowers from seed throughout the several acres of my property in the Hill Country near New Braunfels. Once estalished will they reseed without any help from me? The flowers include Mexican Hat, Indian Paintbrush, Firewheel, Blanketflower, Gloriosa Daisy, Purple Coneflower, Red Corn Poppy, Texas Bluebonnet, Tickseed, Cosmos, Black-Eyed Susan, Plains Coreopsis, etc.. Thanks again for your help!

ANSWER:

Ratibida columnifera (upright prairie coneflower) , Castilleja indivisa (entireleaf Indian paintbrush) , Gaillardia pulchella (firewheel) , Rudbeckia hirta (blackeyed Susan) , Echinacea purpurea (eastern purple coneflower) , Lupinus texensis (Texas bluebonnet) , Coreopsis grandiflora (largeflower tickseed) , Cosmos parviflorus (southwestern cosmos) and Coreopsis tinctoria (golden tickseed) are prominent among the wildflowers that blanket Texas in spring. Papaver rhoeas(corn poppy), is a non-native (European origin) which is widely naturalized throughout the U.S. This is also true of Leucanthemum vulgare(oxeye daisy) and most of the larkspur we see – Delphinium ajacis(rocket larkspur), commonly. Since popular and scientific names of the plants you mention are overlapping, I’ve tried to identify species that are found in many seed mixes.

The joy of these plants is that they will reseed and self-perpetuate. I’m sure Lady Bird Johnson is somewhere out there smiling at you! They will perpetuate in their own good time and way, however. To do a little anthropomorphizing, these natives are savvy to their surroundings and seeds often germinate only when the fall/winter growing conditions favor the early survival that particular kind. Thus some years we are inundated in blue; other years are more yellow-and-red-hued. You will probably find that some species are a lot more prolific than others as well. If they return somewhat unevenly or get out-competed for a few years you might end up reseeding a species or two. And in the random cast of seeds, you’ll probably find that the species self-sort so that different varieties will predominate in niches that particularly favor their ideal growing conditions.

Some of these varieties can be biennials, depending on the conditions, and Castilleja indivisa (entireleaf Indian paintbrush) thrives by growing into and tapping the nutrients in other plant root systems, particularly those of grasses. Thus its success depends on finding a willing partner.

So – yes, you should be seeing the fruits of your efforts for years to come!

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