How To Grow Cosmos & Free Give Away

Rose Bon Bon Cosmos

Cosmos are just about the easiest flowers of all annuals to grow. They are hardy, do not need rich soil, self seed, are not prone to many problems or pests. This is all great news as they are also the prettiest of flowers with their delicate petals on tall stems, and frond like foliage.

The flowers are magnets for birds, bees, and butterflies, as well as the beneficial insects (lacewings, parasitic wasps, tachinid flies, hoverflies) that feed on the pest insects and pollinate your food garden.

Rubenza and Rosetta cosmos.

Cosmos can easily get as tall as 6 feet, though can also be a dwarf variety for pots and border plantings.

Growing Cosmos

To direct sow cosmos, the directions always say to sow after your average last frost date. This is probably sound advice though I have always sown mine a week or two before. On Vancouver Island, in a zone 7, my last frost date was April 28th but I would sow the seeds on any dry day from mid to late April, whenever the garden soil was workable.

Here on the prairies, in a zone 3 with a last frost date of May 20 ish, I sow anytime in May that we have conducive weather.

Blush Cupcake Cosmos

Direct sowing is the easiest way to grow cosmos, though they can be started indoors to get a head start. To direct sow...

1. Choose a full sun, or mostly all sun location. They do not need amazingly rich soil, will grow well in just average soil. In fact, if the soil is too rich, they will be more foliage than flowers.

2. Run the hoe through the bed to knock down any weeds that are growing or germinating. I like the Winged Weeder (also called a triangle hoe) as it just slices underneath the surface of the soil, unroots and knocks out weeds without digging into my garden bed.

3. Rake the soil to level it out.

4. Sprinkle the seeds on the surface of the soil. Push the seed slightly into the soil with your finger, making sure the seeds are 3 to 6 inches apart. The seeds should be just covered with soil so it is about 1/4 inch underneath the surface.

5. You can also sprinkle some soil or compost over top of the seeds rather than poking them in.

6. Tamp the seeds into place with the back of the rake.

7. Water them in. Water daily till the seeds have germinated, then you can cut back to a couple of times a week. Seeds will germinate in 7 to 14 days.

8. As they grow, thin out the seeds so they are well spaced out at 6 to 12 inches apart. You can easily move the seedlings to another spot, just make sure you water them right away so the roots are damp in the new spot.

9. Once they are well established water only as needed, no more than once a week. If you are in drought conditions, cosmos (and zinnias) are the flowers for you. They do not require a lot of water to give you spectacular results.

White Cupcake Cosmos

Do not fertilise or overwater. They thrive in hot and dry.

Growing them along a fence is a good idea for the support.

Deadhead regularly to promote branching and more flowering.

If you want them to self seed, allow the flowers to go to seed in autumn.

To bring the flowers in as cut flowers, you want to pick them in the morning, after they have just opened. Strip off the bottom leaves, anything that will sit in water to keep the water fresh and keep them blooming longer. The flowers should last a week in the vase.

White Cupcake and Apricot Lemonade Cosmos

Some of My Favourite Types of Cosmos

Apricot Lemonade - 2 to 2.5 feet tall. Apricot coloured petals with lilac undertones.

Apricotta - 3 to 4 feet tall, slightly ruffled edges, shades of blush, apricot, and rose.

Candystripe - 6 feet tall, white petals with pink edges.

Cupcake White - 2 to 3 feet tall, look like frilly cupcake liners.

Cupcake Blush - 2 to 3 feet tall, look like pink frilly cupcake liners.

Psyche White - 2 to 4 feet tall, frilly double white petals

Rose Bon Bon - 2 to 4 feet tall, frilly, multi-layered, poufy pink flowers.

Veloute - 2 feet tall. Dark velvet red flowers, others are white with red stripes, and variations of the colours mixed on the same stem.

Xanthos - dwarf stems, pale yellow to creamy white blossoms.

Xsenia - 2 feet tall, terracotta with rose pink undertones.

These are just some of the newest varieties, ones that I surely do love, but the seashells and old fashioned colourful ones never go out of style!

The Giveaway!

Cosmos Apricotta, Saponaria, Lavatera, & Cosmos Double Click Rose Bonbon

'Shades of Pink' Contest

Saponaria aka Soapwort - can be direct seeded or started indoors Indoors 4-6 weeks before the last frost, or directly into prepared soil after the last frost.

Space 12" apart.

To harvest as cut flowers, pick early in the morning to prevent wilting. Harvest when 3/4 of the flowers on a spray are open. 

Lavatera aka Annual Hibiscus - full sun location. Grows in average soil and rocky soil.

Mix some compost into the soil prior to planting or drench plants with a liquid fertilizer in summer to prolong bloom time.

Space 12 inches apart.

Sow seeds where you want them to grow at about the time of your last spring frost. Or, start seeds indoors to get a head start on the season, and set them out after the last spring frost has passed.

Harvest blossoms to use as cut flowers just as they open. Snip off old flowers once a week to promote blooming time. If you allow some seedpods to ripen and fall, lavatera may self seed.

2 types of cosmos, the Double Rose BonBon and Apricotta.

How To Enter

Prize: Win these four packets of lovely annual flowers to add colour to your yard, grow flowers for your cutting garden, and feed your pollinators, too. A $25 CAD value.

To enter, all you need to do is put a comment below. I will choose a winner at random after the contest closes at midnight of April 2nd. The winner will be informed by email and I will send the seeds to you right away. Plenty of planting time.

Terms & Conditions - Must be a resident of Canada as I cannot ship the seeds out of country. Thank you to Madeline at Fraiche Flower Farm for the seeds.

Ps, if you enter as a guest, that is just fine, but please put your name after the comment so I know who you are : )

Good Luck ~ Tanja