Following! I'd like to know too.

anyone? I'd love to save this plant if I can. it was weirdly expensive.

Since you posted to the Northwest Gardening forum, I'd assume you are located in the PNW. Lavender is dead easy to grow here IF you follow the guidelines.......full sun, a well drained and lean soil, just enough water to get established, then NO extra irrigation and NO fertilizer. I recommend cutting back twice a season. Once in fall, removing the old flower stalks and a short flush of foliage....maybe just an inch or so. Then in spring as the plant starts to push new growth, I'd take it back a bit more (but never into bare wood). This will keep the shrub compact and dense for as long as possible and increase the flowering stems.

But it won't remain looking good forever. Lavenders start developing a very woody, gnarly interior after a few years, then begin to splay or flop open and should then be replaced.

I'd leave the struggling one alone for now and see how it does the rest of the season. That center dieback looks like a water issue to me and I'd wonder if in that location the soil is too moisture retentive or lacks very fast drainage. It doesn't share the same kind of growing conditions as that azalea next to it..........

"Weirdly expensive" is pretty unusual for a lavender plant :-) They are typically very inexpensive....quart sizes no more expensive in spring than a similarly sized vegetable start and larger sizes less than most perennials of equal size.

yes, I'm in Seattle. Lavendar is everywhere in my neighborhood. I'm ok with what it will grow into when it's older. I like a wild and crazy garden style, and will remove them when they're way too old and woody. (see the crazy old rosemary behind them? I love it.)

I'm kind of thinking that the half-dead one is possibly a problem with the plant itself and not anything I did. the two healthy plants are inches away and they all get the same exact treatment. I know that sometimes a plant is already failing to thrive at the nursery and you can't tell right away. my main question was whether it would help to trim the dead part or fertilize it. but thanks to your advice, I'll just leave it alone and see what happens.

as for it being expensive: I bought them at Swanson's nursery for $15 each. I found out later through friends that it's a very hoity toity nursery. Thankfully they gave me a list of more reasonable places to shop in the future.

ha, I hope I didn't offend. it was SUPER nice! I'll definitely go back if I want something really special. I tried Swanson's because so many of the box stores had failed me -- many had bad inventory (this was pre-covid). plus, every outdoor plant I bought at Lowes died so I'm weary of them. (could be a problem with me, haha.)

but if I need more cheap easy local plants, I'll try fred meyer, mclendon's or the nurseries my friends recommend. one rec is in west seattle. I live in South seattle so at least I can drive through georgetown to get there.