One of my 2 Sedum groundcovers got destroyed - what happened? (pics attached)

[Sweets777]

I bought two Sedum "boogie woogie" yellow flowered groundcovers, planted them close to each other in the same soil and have been watering them equally, but one was decimated over the course of a month after planting. It has now been in this sad-looking state for about two months, no better, no worse. The other one seems to be thriving, no issues.

I've noticed small milkweed bugs (Lygaeus kalmii) around the plant on a couple occasions, but otherwise no obvious sign of pests - those aren't supposed to really damage plants right?

I've attached pictures below, one picture of the healthy plant with several pictures of the diseased-looking one. Also included a picture of bubble-looking things in the soil but assuming this is osmocote/slow release fertilizer?

Any ideas on what might be going on - Is there any particular condition that makes sense here? Should I leave the plant in the hope that it will come back strong next year or instead dig it up?

 

[Tetters]

As this problem is so similar to the one with your habanero, I`m wondering if there is an insect attacking the roots Here in the UK I would suspect vine weevil, or root aphids. If you dig those plants up you could inspect the roots - do please let us know.

 

[Owdboggy]

Also suspect too much water. Sedums should not need watering after planting. They are succulents after all.

 

[Sweets777]

Also suspect too much water. Sedums should not need watering after planting. They are succulents after all.

I really haven't been treating these like the succulents they are, watering them on the same schedule as other non-succulents and even recently mulching. Will definitely be changing things up in that regard. Since both sedums were receiving the same amount of water I didn't suspect that, but it could just be luck or that one of the plants was stronger than the other hence a resistance to overwatering/

I'd still be curious to dig it up and see if anything is going on below ground, and will probably do so soon, as I'll probably be relocating them to a non-mulched area.

 

[Tetters]

I always water my sedums, maybe not as often, but all plants need some water.
As an afterthought @Sweets777 it is very easy to make cuttings with your sedum plants so you could probably get a dozen or more new plants from what you have there

 

[Owdboggy]

I rarely water any plants once they are in and settled. All watering regularly does is to discourage the pl;ants from sending out roots looking for water, so they do not get really well established.

 

[Sweets777]

Seems pretty situational, dependent on rainfall and the water needs of each individual plant... Also I've heard that you'd generally water newly planted plants a bit more than you normally would to help get them established, and similarly ensure perennials get consistent water for their first season after which you can be much more hands-off.

As for my Sedums, safe to say I've been watering much more than they actually need - I think the key is to give these water "breaks" where the soil remains fully dry for a period of time.