Ageratum Doesn't Have to Be Tricky To Grow

Ageratum is one of those annuals that if you can grow it, you can be the envy of the neighborhood.  And I understand that some folks have problems with this lovely blue flower so here are the tips for success.


In USDA zone 4/5, plant seed from late February through March and you'll be fine for timing and blooms in early June.

This seed requires light to germinate (that's where a lot of you go wrong) so the trick here is to pat down the soil, and lay the seed directly on top of this firmed soil. 

Pat down the seed to ensure it is in contact with the soil so when you water, you won't wash the seed down the side of the pot (where they seldom germinate).

Use a warm soil temperature of at least 75F,  80F/27C is much better.  

Seeds should be up in 7 days.   Note that if you try to germinate this seed in cool soils, it will simply rot away.

Always use warm water to water this plant.   I hope you're getting the message that this one likes to be warm and doesn't like cold in the seedling stage.

Once you grow it to the 4-leaf stage (it has 4 true leaves) then you can transplant it into its own pot or cell in a pack.   Then you can drop the growing temperature down to 60F/16C.   

And this too is important.  Once the plant starts to mature, it won't like warm temperatures but prefers the cooler growing conditions (still use warm water to irrigate).


Growing Conditions

Plant outdoors after all danger of frost; although I note that this plant if acclimatized and has been outdoors for a week will usually shrug off a light frost.

Plant in the full sunshine.

Water and feed regularly.

Deadhead spent blooms to encourage new growth and blossoms.

Click Here For Gardening For Beginner Gardening ebook

Book cover Gardening Non Gardening


Watch this plant for spider mite.  Not much else bothers it.

Shopping Resources for this Page

You can find several ageratum seed sources here

Want A Stunning Garden? Click Here For Your Free Lessons