Amber sent in this question which I answer below.

Q: This will be my second year with my ko roses. The problem I’ve been having is they are all scragly, only growth mainly at the top of the branches. I pruned them a little during the growing season but they didn’t fill in.They were repeat bloomers and are still producing. I want a prettier fuller bush. What can I do to make this happen? ( Panama City Fl.)

Hi Amber,

A: The loss of leaves on the lower part of the knock out rose is more than likely caused by a fungal leaf disease like black spot.

Though knock out roses are supposed to be disease resistant, mine still succumb to some black spot due to the hot, humid summers in my area. With black spot, the plant’s older lower leaves are affected at first, getting black spots on them, then yellowing, then falling off the plant.

So you end up with a scraggly knock out rose plant with growth on the top half of the plant and not much on the bottom half. In hot, humid areas, you can’t get rid of black spot completely but you can manage it with good garden hygiene and a regular spray program which is discussed in this article on black spot.

If black spot isn’t affecting your knock out roses (though I’d say it could be considering you live in an area that has hot, humid summers) and you want prettier, fuller rose bushes be sure to give them a good annual prune as discussed in this article on pruning knock out roses, (best time for this in your area is February)  and be sure to feed them regularly during the growing season; every 6 weeks from early spring to mid autumn in warm areas like yours.

Paula from SE Michigan writes

“I recently purchased and planted two Blushing Knock Out roses. I live in SE Michigan and the nursery told me to plant them right away, which I did this week. So far, they look great. Here’s my question: I ordered one more which is not scheduled to ship until Nov. 9 and am wondering if I should also plant that one or keep it inside until spring? Also, should I cover the other 2 for the winter (I put a lot of mulch at the bases)? Thanks in advance!”

Hi Paula

Nov 9 is going to be another month away from when the nursery told you to plant your knock out roses “straight away” so you might be pushing it. I’d play it safe and keep it in your garage until spring. Water it once a month and it should be fine.

SE Michigan is considered USDA zone 5 (some say USDA zone 6 now due to the climate getting warmer) and from research I’ve done there are mixed opinions about whether to protect knock out roses in winter in zone 5; some folk Read more »