Late yesterday afternoon I made a trip around the borders with my hedge shears in hand. I wanted to get late summer and fall bloomers like phlox, mums, solidago, and giant rudbeckia cut back before the anticipated soaking rain arrived.
If I had to start over with my gardens and borders, I’d especially have a lot more of these fall bloomers. They look good in the spring, the summer — even during drought –, and are spectacular in the fall. But like everything, there’s always that little secret that will enable these plants to receive a #10 rating rather than just a #5 on a scale of 1 to 10.
Most gardeners I know who don’t know this little easy piece of information are always complaining about how the mums get so tall, fall over, and look ugly when they bloom. Or about how the phlox is too tall and awful looking.
Many times gardeners who know this little tidbit, still won’t do it. They just can’t bring themselves to believing that the plants will recover from such brutal treatment and look gorgeous as a result of it. Even if they’ve seen proof. (I know this for a fact because I’ve had gardeners come here, see, learn the secret and then come back and tell me they just couldn’t do it and so their plants were still awful looking in the fall.)
The Secret
Mums and phlox have grown profusely over the last two weeks. Yesterday, some of mine were a foot high and others were 2 1/2 feet already. I cut them all back to the ground!
Sometime in May they will make a full recovery and then I’ll cut them by half. At the same time I’ll take out thin stalks and leave the stronger ones. (If you haven’t already taken out unwanted growth earlier in the spring, now would be the time.)
A couple more times before July 1st, I’ll pinch or cut the top inch or so off the mums. Just to insure they look their best.
Other late summer and fall blooms that benefit from cutting back severely
- With garden-worthy solidago you don’t have to do as much. Just trimming the taller stalks back is enough to increase the plants fall display.
- Plants like Giant Rudbeckia that can reach 10 feet or more, need to have their lush spring growth cut to the ground. Whether you’ll cut them again in a month or so depends on how short or tall you want them. I usually cut my Giant Rudbeckia twice and then in bloom time the stalks stay at about 4 or 5 feet — just the right size for my borders.

Giant Rudbeckia will grow 10 feet or more if you don't cut it early in the season. This 4 1/2 feet size is just the right size for my Fence border.
- Heliopsis, Helianthus, and Asters also benefit from cutting lush spring growth back to the ground.
Final Thought
This is an easy little secret that can take your fall borders to the next level of beauty! Cut now to ensure a greater fall display.
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Related Posts:
Phlox and Mums – A Timely Tip
Mums – Flowers – The Crowning Glory of Falls Display
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Organic Gardening is easy, effective, efficient — and it’s a lot healthier.
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Thanks for the information on flowers! I have focused most of my attention and energy on edibles but I do have one native wildflower bed that includes Rudbeckia lanciniata (Green-headed coneflower). Last year (its 1st year) it got at least 5 foot tall which is probably a bit taller than I would prefer. I’m wondering whether it would benefit from a haircut this spring just like your Giant Rudbeckia. What do you think?
In my opinion Steve, I definitely think it would benefit from a haircut. If you cut it once and then find it’s still taller than what you would prefer —- next year cut it twice. Once about this time and then again in 4 to 6 weeks. Or instead of cutting all the foliage down the second time — just cut the stalks down.
Let me know what happens.
Theresa
Theresa, I wonder if you could root any of those cuttings – ever tried it?
The cutting of Mums, phlox, heliopsis, helianthus, and asters can be rooted. I don’t think cuttings are the way to go with solidago and rudbeckia — but rather root division. Actually, root division is so easy for mums — I wouldn’t bother with cuttings. Phlox is easy either way. Heliopis and helianthus is easy from root division.(They usually have to be cut apart rather than easily pulled.) If the parent aster is your own plant I’d go for root division. If it belongs to someone else I’d go for cuttings.
Sandra, most of these plants are such strong growers, that when you get them going you won’t need to propagate unless you’re going to sell them. 🙂
I don’t have any of these, but that’ll have to change. They are workhorses and lovely – I especially like that purple Aster.
It really is more pink than purple Sandra. It’s Alma Poetschke I think. Aster get “bare legs” but they make such a show, it’s hard not to have some around.