10 Reasons Cosmos Are Good For The Garden

orange cosmos against sky

Some plants can get overlooked in the seed catalogs for being too simple or too common. Don’t let cosmos be one of them, as these are some of the most beneficial and multipurpose flowers you can grow. They’re also low maintenance, so anyone can grow them, even if this is your first year putting in a garden or planting some containers.

From attracting pollinators to thriving in poor soil, cosmos earn a place in any garden.

Cosmos Are A Cut and come again flower 

Cut and come again flowers will produce new flowers each time one is picked, and cosmos take a prime spot on this list. They’re the everlasting gobstopper of cut flowers, and you can easily get hundreds of blooms from just a few of these highly productive plants. 

When you harvest cosmos for a bouquet or deadhead them, cut the stem at least a foot down from the flower, just above a leaf junction. The deep cut promotes new growth, and in just one or two weeks, there will be a new stem with a flower bud ready to open. 

Even cut and come again flowers can be refreshed, though, so a second sowing of cosmos will avoid any slowdown in flower production if you have the time and space. Sow your first round in spring as soon as the soil has warmed. Set out seeds again one month later, and you’ll never lack for flowers.

If cut and come again flowers are new to you, I wrote an article all about them: Cut and Come Again Flowers: What Are They And Which Should You Grow?

Cosmos flowers attract pollinators and beneficial insects

“There are enough bees in my garden already,” said no gardener, ever.

Cosmos are one of the best flowers to add to a pollinator-friendly garden. Bees, butterflies, lacewings, ladybugs, and parasitic wasps are just some of the beneficial insects that will gravitate to your garden when they see a planting of cosmos. 

The open, saucer-like flowers of cosmos are perfect for the insects to land on, and the rich yellow center provides pollen and nectar. While the bees are flying from flower to flower, they’ll also stop by your tomatoes, cucumbers, and any other vegetable you have that needs pollination.

red edged cosmos
Verigated petals are a bee-attracting feature of cosmos.

In addition to pollinating your food crops, beneficial insects will eat pests such as aphids, beetles, and caterpillars. Lacewings are delicate flying insects that eat thrips, mites, and aphids, and you’ll often see them crawling on the underside of cosmos leaves looking for prey.

Include at least some single flower varieties that have an open bloom. Double flowers are pretty, but some are harder for bees to get to the center when full petals block the way.

Recommended varieties:

  • Picotee: Pink petals edged in red are beautiful in the garden and do a great job at pulling in polinators.
  • Ladybird: Semi-double blooms allow access to the nectar-rich center while also being slightly more frilly than a single bloom. Butterflies love the orange, yellow, and scarlet flowers.

Birds love cosmos, too

Bees and beneficial insects get all the attention, but birds are an essential part of the garden, too. Birds will swoop in to eat caterpillars, assist in pollination as they drink nectar from flowers, and help spread flower seeds they forage from your plants.

Birds will use tall flower stems as a perch, including cosmos. One year, I had a problem with armyworms in my garden, and to my delight, orioles eventually showed up, perching on the tall flower stems and scouting for worms.

Hummingbirds love to visit cosmos, too. As they drink nectar, their beaks also get pollen stuck to them, which they transfer to the next flower they visit.

hummingbird on cosmos
Catch a glimpse of hummingbirds on your cosmos if you’re fast.

Once cosmos flowers go to seed, birds will stop by to pick them out. The large seeds make for an easy meal, so don’t be surprised when you see cosmos flowers germinating in new areas of your garden, thanks to the birds dropping them.

Cosmos flowers are perfect for beginner gardeners and kids

If this is your first year gardening, or you have small children along for the ride, then cosmos should be on your shortlist of flowers to grow. The large seeds are easy to handle, and once germinated, they grow quickly. If you start them indoors, they’ll be ready to transplant outside after about a month or so. 

You can also direct sow them by scattering seeds a few inches apart in a sunny location. This is an excellent task for kids. They get to sprinkle the seeds on the soil, and you get your planting done for you.

Cosmos don’t need a lot of attention while they’re growing, so as a beginner, you don’t have to fret over and pamper your plants. Just water them once a week. 

Once the flowers mature and bloom, what better way to get a close-up view of pollinators and beneficial insects than to watch them visit the cosmos flowers? Thanks to the open bloom and rich nectar source, even bumblebees will make an appearance. Watch the weight of the bumblebee set the flower swaying and explain to the kids the result of pollination. 

For a walkthrough guide to growing cosmos, be sure to check out this article: Are Cosmos Easy To Grow? Yes, Especially From Seed!

Cosmos are Perfect for Growing your own cut flower bouquets

Who doesn’t love a bouquet picked straight from the garden? A patch of cosmos will keep you stocked with cut flowers through the whole season, especially if you plant a few varieties with different maturity dates. 

Some cosmos produce flowers in as few as 60 days, while others take just over 100. With this range in maturity, you’ll always have new flowers opening up that you can pick early in the morning and put into a vase of cool water. 

pink cosmos in vase
Simple and charming, cosmos make a perfect bouquet flower.

You might have some cosmos stems that droop after you cut them, even if you get them into the water right away. If that happens, you can pull out the drooping stems and either replace them with other cosmos or diversify your bouquet with a few stems of a different flower.

Some gardeners say they have fewer instances of cut cosmos drooping when they grow double bloom varieties. These flowers have multiple rows of petals, giving them a fluffy appearance that stands up well in the vase.

Recommended varieties:

  • Double Click Mix: This is one of the varieties I’m growing this year, with blooms in shades of pink, white, and red.
  • Versailles Mix: Develeoped specially for cutting, this mix produces single flowers in pink, white, and cranberry red.

Cosmos Can Be A Trap Crop

Even though cosmos are fantastic flowers for attracting beneficial insects, they are not immune to harmful ones. Aphids, in particular, love to feast on cosmos plants, which makes it a good lure or trap crop if you have a more valuable plant that you want to protect. 

Aphids are a pest in any garden. These tiny green insects bite plant leaves and suck the sap out. While it won’t kill a healthy plant right away, the damage will cause the leaves to fuel, turn yellow, and even wilt. If a plant is infested with aphids, the insects can overwhelm the plant and kill it. 

If you use cosmos as a trap crop, the idea is to sacrifice the cosmos to aphids and other pests, so they stay away from your prized plants, whatever they are. For some gardeners, it’s roses. Others want their edible crops to make it through the season without aphid damage. 

Since cosmos are such robust plants and grow quite large, they can generally withstand the damage. Even if some stems and leaves show furling or discoloration due to the aphids, there are plenty more to enjoy.

Cosmos Seeds Are Easy To Save For Free Seeds

If you’re just getting started with saving seeds, cosmos are an easy flower to practice on. With an abundance of blooms, there will always be one going to seed that you can collect.

Cosmos seeds are large and thin, and each flower produces dozens of them. To collect them, leave the seedhead on the plant until it is completely dry and the seeds are brown. Pull the seedhead off and either flick the seeds off the base and save those, or pop the whole seedhead into a paper envelope and let the seeds fall off on their own.

cosmos seed head
There are enough seeds on cosmos flowers that you’ll never have to buy them again.

Make sure you save seeds from heirloom or open-pollinated varieties so the seeds grow to look just like the parent plant. Hybrid varieties don’t always grow true-to-form when you save the seeds since you have to have specific parent plants to get the hybrid.

Baker Creek Heirloom Seeds is a great company to shop with, as they only sell heirloom seeds that gardeners can save from year to year.

Recommended varieties:

  • Sensation Mix is one of the original cosmos varieties grown in home gardens. The seeds are large and easy to plant, and they’ll return the next year looking exactly like the parent plant.
  • Bright Lights produces flowers in orange and yellow shades, making a statement in any garden. Plus, it’s a nice way to add variety to the usual pink and red tones of cosmos flowers.

Cosmos Put poor soil to work

If your garden has poor soil, you can still grow beautiful flowers, including cosmos. These flowers appreciate average to poor soil, as too-rich soil will promote leaf growth and hinder flower production. 

As long as the soil is well-draining, cosmos will grow just fine. Save your compost for heavy feeding flowers and vegetables. 

Along the same lines, don’t worry about giving cosmos any fertilizer through the growing season. Like adding compost, applying fertilizer will promote leafy growth rather than flowers. 

It’s nice to have an option for something to grow when your soil is less than ideal, so get those cosmos seeds at the garden center even if you’ve never been able to grow anything before.

Cosmos Flowers Add charm to any garden

Even if your garden is practical and focused on function, there’s no harm in growing a few cosmos to add a touch of charm and sweetness. I grow lots of vegetables in the summer for fresh cooking, but adding cosmos flowers here and there transforms my food garden into a French potager. 

Seeing cosmos flowers dancing in the breeze with their lacy foliage and saucer-like flowers makes me smile while tending to garden chores or completing a quick harvest before dinner. 

pink cosmos in field
Beautiful cosmos add a little romance to any home and garden.

Cosmos don’t need to take up a lot of room if you’re reluctant to give up space for them. While some varieties grow to four feet or taller, others stay a compact two feet tall or even less. With dwarf varieties, you can tuck a few plants in between your tomato trellises or in a pot for your patio.

Recommended varieties:

  • Rubinato: A dwarf cosmos that grows to only 12-24 inches tall, the cranberry red petals will cheer up even a small garden.
  • Xenia: Growing to just 24-28 inches tall, Xenia looks similar to Rubinato but is more compact. Petals are light and dark pink.
  • Sensation Mix: If you have the room, why not get an impressive show from this variety that will grow up to five feet tall? Flowers are in shades of pink, white, and cranberry red and will bloom all season long.

Cosmos Plants are drought tolerant (Great for water restricted areas!)

When the seeds are germinating, and the plants are young, cosmos need regular water, to the tune of one inch per week.

To easily keep your plants watered without having to think about it, I recommend setting up drip irrigation on a timer. Drip irrigation delivers water to the base of the plants according to whatever schedule you set up. I set my system to water the garden at 4 am so that the plants have all the water they need to start the day fresh and perky. 

Once the plants are established and have reached their mature height, you can cut back the amount of water you use to irrigate. Try dropping down to just half an inch of water each week, depending on your climate. If you notice the cosmos plants starting to wilt well before their next watering, give them some extra and fine-tune the process as you go. 

If you don’t need to monitor your water consumption, you still should be careful not to overwater your cosmos, as this could actually prevent them from flowering. Read more about that here: 4 Reasons Your Cosmos Aren’t Flowering (And how to fix it)

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