Reader Questions: Should I Deadhead My Perennials?

Today’s Reader Question comes from Charlene in Charlottesville, Virginia:

I have planted a perennial border that also has some Knockout Roses. I am wondering if I need to deadhead the perennials and the roses. I am growing Salvia ‘May Night’, Coreopsis ‘Moonbeam’, daylilies, German iris, Scabiosa ‘Butterfly Blue’ and Salvia greggii. I’m sorry to list all of the plants but I don’t know if I should deadhead them. Thanks for your help in advance.

This is a great question that I’m sure other Mid-Atlantic Gardening readers have so thanks for asking! Let’s go through each of the plants one-by-one and discuss which ones need to be deadheaded.

  1. Knockout Roses – part of the beauty of growing Knockouts is that they don’t have to be deadheaded. If you have the time and/or energy, you can deadhead them and be rewarded with a few more blooms. But be very careful with sanitation to avoid spreading Rose Rosette Disease.
  2. Salvia ‘May Night’ – you don’t have to deadhead these beauties. The easiest way to deal with the spent blooms is to wait until most of the first flush is over and then cut them all off at the same time. You’ll be rewarded with another flush of blooms…and another…and another.
  3. Coreopsis ‘Moonbeam’ – the lemon yellow blooms of Moonbeam will eventually fall off and you’ll be left with a brownish-black blob of spent blooms. If you cut the whole plant back (you should see new growth starting at the base…if you don’t then don’t cut the plants back until you do), your plants will start reblooming in a few weeks.
  4. Daylilies – daylilies are called such because each bloom lasts for only a day. If your individual blooms are spent, just snap off the spent bloom. If the entire bloom stalk has finished blooming, cut that stalk back to the base of the plant. Here’s a tip to get a second flush of blooms, even if your daylilies aren’t the reblooming type: when your plants finish blooming completely, cut all the foliage back to within 3″-4″ of the ground. Your leaves will come back out and look fresh for the summer and you’ll probably get a few extra blooms to boot.
  5. German Iris – while daylilies can be forced into a second bloom period in most cases, German iris can’t be. I don’t like to say “can’t” with so much authority but I’ve never seen German iris rebloom from being deadheaded. What I have seen are wonderful reblooming irises like ‘Immortality’.
  6. Scabiosa ‘Butterfly Blue’ – Scabiosa, or pincushion flowers, are best if they are deadheaded when they finish their first flush of blooms. Their bloom habit is similar to Salvia ‘May Night’; they don’t have to be deadheaded but if they are, you’ll be rewarded with more and more blooms.
  7. Salvia greggii – I love this plant! I’ve never had to deadhead it in the landscape…it literally blooms from April through November and never misses a beat. There are so many blooms that you never notice the spent ones. More people should grow Salvia greggii and I should do a post about it…thanks for the reminder!

 

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Scabiosa ‘Butterfly Blue’ will reward you with more blooms if you deadhead them

 

Charlene, I hope that this gives you some answers regarding whether to deadhead your perennials. I wish you all the luck with your perennial border! Annuals are fantastic for splashes of color but, in my opinion, perennials are what hold the landscape together.

If other Mid-Atlantic Gardening readers have thought on deadheading perennials, leave me a comment below or e-mail me.  If you enjoy being part of the Mid-Atlantic Gardening community, join our e-mail list (upper right hand corner of this page), become a fan on Facebook and follow me at Twitter. Happy gardening!