Hi I'm in 10 florida so grow most everything outdoors. With almost all plants the dividing line is freeze or 32 degrees. This will make them annual for sure lol. Coleus originated in Africa and has been hybridized into at least 800 cultivars.Some are anuuals and some are definite perrenials. All can be propagated from tip cuttings so will live on .This makes it unimportant which is which lol. The annuals will flower then die so keep flower heads trimmed. This is really the dividing line on most "annuals" without regard to temps. The term is actually applied incorrectly as a "garden " term rather than growth habit.They usually mean it can't tolerate freezing. Of the annuals " you're interested in overwintering check on the origin..If tropical or subtropical "annual can mean as much as ten years. Maid That truly is a magnificent plant.but makes me want to grab my pruning shears lol They are an incredibly noxious weed in warm climates. I remove at least a bushel a week from my hedgerows lol. there is that old saying "one mans treasure is anothers weed lol. i remember looking at pix of a garden in Malaysia and she apologised for the "weedy' sealing wax palms.lol. Wish i had that weed problem !!! i can't one past 3 years gary

Spraying poplar suckers has potential to damage the parent tree. Fine mulch is ideal for getting lots of new little plants coming up, as mentioned. Paper mulch is best for smothering weeds in an area that is going to be made into a bed later, rather than as a routine maintenance tool. You put down a thick layer and get it wet, keep it wet. Also a decorative mulch may be put over the newspaper layer, if desired. Coarser mulch such as clean arborist wood chips or purchased play chips is the most effective, however as has been pointed out in response to one of my posts on this site there can be issues with smothering when such materials are used near herbaceous plants. Even when applied some distance back chips may often migrate and get on top of perennials. Really if you are going to have flower plantings of much size and scope you can expect to be out there hand weeding etc. as a matter of course. If working among your flowers like this is more a vexation than a relaxation then consider making some changes. One way to include herbaceous plants in a home landscape without the upkeep being too much is to have one small or smallish area where these are planted, with the rest in lawn and woody plants (mulched with wood chips). This post was edited by bboy on Mon, Aug 18, 14 at 15:14

SC Gardener, I garden on extremely compacted clay sub-soil (all topsoil was removed by the builder and trucked away when our house was first built). Parts of my Z5 garden are only a few years old, other areas have been improved by gardening on them the past 15 years or so - but it has always been a very hard go, especially since I have not been allowed to raise the grade in most areas of the yard. FWIW, from your list, I have been able to get most perennial geraniums to grow. Geranium cantabrigiense (x) Biokovo, also the similar pink one Karmina, Geranium cinereum Splendens, Geranium endressii Wargrave Pink, Geranium oxonianum Rebecca Moss, Geranium sanguineum & sanguineum Ankum's Pride, have all been in my gardens for more than 5 years, plus several others that have overwintered for a couple of years. I would give the geranium family a retry if I were you. Anemone - there are many kinds - I have had good success with two bulb varieties Anemone Blanda and Anemone sylvestris, both perennialize wonderfully (I grow them under trees where it is drier). However, I had a very tough time getting the perennial Honorine Jobert to thrive in my garden - 3 plants at 3 times (9 total - I can be stubborn lol) to get 3 survivors, 2 were pretty stunted after a few years and removed, the other is currently growing like a weed. I was told on the GardenWeb that one of the problems with them here is that they are often for sale in the fall (when they are pretty in bloom) and need to be planted in the spring to settle in well. Valerian over-wintered for me for several seasons, but had very little spread/growth in subsequent years and just wasn't there one spring. I didn't try repeatedly to grow them as I did with the HJ anemone because the color of the ones I planted were washed out looking. Delphs look lovely but only last a few seasons. I replace/add to them fairly frequently. Saqe - sage - salvia, I presume, vary somewhat but some will grow well in the drier parts of my garden. May Night & Caradonna do well for me and are long-lived. Marcus, a dwarf variety, gave me only 2 years. The culinary sages grew very well for me, but do tend to get woody fast, and I replace them every few years. All of them grow best for me with a little gravel in the planting hole, or near rocks or concrete walkways, etc. Firewitch dianthus is the only dianthus that is truly perennial for me. I was very surprised to here that yours died. Other kinds are very iffy, even to overwinter a season or two. The biennial ones, however, are usually capable of giving 3 to 5 years - don't ask me why! Ornamental grasses - miscanthus, panicums, calamagrostis (called something else now) all do very well, while the pennisetums are a bit more difficult (try the rocks/gravel thing for some of these). The silver blue things (except for the panicums) seem to be very questionable here, for example, Blue Oat Grass works best as an annual in a pot and Elijah Blue fescue survives but heaves a lot. Sedges make a good replacement for some of the smaller grasses. Most campanulas are short lived for me, even the dreaded spreader glomerata only managed to be a well-behaved, but fairly tender plant for me, which would die out for no reason every 3 or 4 years. Coreopsis - only long-lived one for me is Moonbeam, the rest 3 years tops, with the really bad pink ones strictly annuals. Creme-brule (multiple plants) lived 2 seasons only. I eventually found it more fun to buy various coreopsis seed packs in spring and sprinkle them in pots for mid/late summer placement in those inevitable dull spots in the garden. Lady's mantle grows like a weed for me and seeds into every crack in the sidewalk as well as the soupy parts in the low areas of my yard, in full sun or full shade. Maybe you could retry that one. From your second list - ajuga, achillea, agastache, & artemisia are all problematical for me. One of our local nurseries cautions buyers about using Ajuga as a groundcover, others sell them in flats for unsuspecting buyers. Caitlin's Giant ajuga is a definite annual for me, no matter where I plant it or how I plant it. Burgandy Glow usually overwinters, but may disappear (the whole big patch) at anytime thereafter. Grows best under the eaves or next to a walkway in my garden, the same with Chocolate Chip. Achillea' Moonshine is the easiest one for me - will grow, but not spread around excessively (or even all that much) and has lasted for years (over 10 years). Paprika and Fireland do fine in the upper garden near the patio, as does Cerise Queen, but it's counterpoint in my pink garden Appleblossom faded away. Agastache - only one you see around here for sale is Blue Fortune. It is supposed to handle somewhat damper conditions than most Agastaches. I have never tried it. I have stayed away from all agastaches because of my drainage issues and because they are too large for my gravel garden. I usually pot grow at least one Agastache a season. Artemisias drive me insane. They won't grow in the garden proper, but overspread their space in my raised gravel garden and spread all over the place. I think I've tried them all with absolutely no good results. I now rely on Lamb's ear - it may rot out sometimes, but always comes back the next season. Just rake out the mess, stick whatever looks reasonably possible to regrow, and forget them. Lamb's ear is about the only silvery plant I can grow - for blue grey green I use Walker's Low catmint, which can get messy but always returns faithfully and can be pruned to shape them and for multiple bloom cycles. Guara (listed by others) - the only hardy variety for me is Whirling Butterflies, pink ones are strictly annuals. Whirling is bone hardy and is currently spreading a bit too much for me (likes the front edge of my beds where they are too tall). I also helped them along by moving all the plants from one corner of the yard to another (while flowers are white - there is still a lot of pink to them which I didn't like in my yellow, blue and white garden) but the removed ones regrew in their original spots as well as in their new locations, bigger than ever, so I unintentionally doubled my quantity. Every year I dig out a few more and trash them. Scabiosa - I bought 12 plants of Blue Butterfly one year when these were a "hot" plant. They bloomed like crazy, but none returned, never tried again. I did have a S caucasica Perefecta Alba which over-wintered a few seasons and then died out. For myself, I would like to add to the list - the heuchera. Some live forever, some die after one season, and lots of them shrink year by year. I know they are wonderful some places but not in my garden. Hardy for me are Palace Purple, Green Spice and Caramel, also one of the more silvery purple ones, with prominent veining whose name I no longer know, possibly Pewter Veil. The rest are a big question mark, and I have tried lots of them.

I have a dedicated annual bed that makes it easier to turn over in the spring. (I don't have to worry about damaging anything) I also tuck annuals in among my perennials for that pop of long lasting color.