Flower of the Week: Cosmos

Flower of the Week: Cosmos

For years I have admired the beautiful flowers produced by Floret, a flower farm in Washington. When I made the decision to purchase the greenhouse last fall, I knew that I wanted to provide my customers with flowers from Floret come spring. I have been growing my Floret seeds for the past few weeks in the greenhouse and now they are ready to be transplanted into your garden!

In my journey of getting to know everything about the greenhouse world, I want to make sure I am sharing that information with you as well. Every week, I will focus on one flower in the greenhouse and provide the planting and harvesting techniques for our area. (I will also be doing this for one vegetable each week!)

So let’s talk about Cosmos!

Cosmos are an annual flower that grow up to 42” tall, so they’re best placed towards the back of your flower beds. The beauty of Cosmos, other than their actual beauty, is that the more you harvest them, the more they’ll bloom. 

How to Plant

From seeds

Indoors - Seeds can be planted into trays 4-6 weeks before the last frost. Cosmos grow quickly so be sure to not start seeds too early or they’ll outgrow their pots. 

Outdoors - Seeds can be sown directly into garden beds after the danger of frost has gone. For this area of Nebraska, that would be around the last few weeks of April/early May. Seedlings will start to sprout in about a week’s time. 

From Seedlings

Seedlings can be planted after the danger of frost has gone. Cosmos are a bushy plant so make sure to plant them 12-18” apart.


As mentioned before, Cosmos do best when harvested using a method called pinching. Pinching allows the plant to branch out and grow even more robustly.

How it works, from the experts at Floret:

When plants are young, between 8 to 12 inches (20 to 30.5 cm) tall, take sharp pruners and snip the top 3 to 4 inches (7.5 to 10 cm) off the plant, just above a set of leaves. This signals the plant to send up multiple stems from below where the cut was made, resulting in more abundant flower production as well as longer stem length.

Erin at Floret also recommends sowing two rounds of Cosmos about a month apart so that you have a variety of flower types and can harvest the blooms from summer into fall. 

Cosmos flowers available at Petal & Stem

Cosmos Rosetta
Cosmos Cupcake Blush
Cosmos Xsenia
Cosmos Rubenza
Cosmos Double Click Bicolor Rose


All images in this post are from floretflowers.com.

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