I grew both ranunculus and anemones in mixed plantings together both in Texas (zone 8) before we moved here and here in southern OK (zone 7). I believe I planted the ones here in OK in 2000.

I planted them in the fall, soaking the ranunculus in water for 4-6 hours first, and the anemones for maybe 12-18, and then planting them. Their foliage emerged around Thanksgiving and stayed low down to the ground. I did mulch them but not real heavily. The ranunculus need a certain amount of cold exposure in order to bloom so they might do better from a fall planting, but I think they'll do okay from a late winter planting here as long as the hot weather doesn't arrive exceptionally early. As long as your ground doesn't get really cold, they'll overwinter just fine in zone 7. I am not as sure about zone 6. They might need really heavy mulch or even a low tunnel to overwinter if you live in zone 6.

Mine didn't get any care whatsoever after I planted them and watered them in as they were in a raised bed down near our front gate, which is about 300' from our house. Obviously I wasn't going to drag a water hose down there and water them. I felt like I'd try to grow them dryland style and see what happened. They grew just fine in well-amended clay soil in that raised bed, surviving for several years only on natural rainfall. They were in a mixed bed of spring-blooming bulbs that included the ranunculus and anemones, tulips, daffodils, Dutch irises, Dutch hyacinths and several different varieties of ornamental alliums. They bloom in spring before the weather gets too hot. Once the heat arrives, they're done.

Over the years, Mother Nature and our weather have weeded out the less hardy of the plants from the bed. The ranunculus lived maybe 3-5 years. They didn't all die at once---it was just that fewer and fewer came back each year. If I'd been giving them proper care, digging and dividing them, fertilizing and watering regularly maybe they all would have survived. In terms of toughness, the anemones lived the shortest time in that bed and those conditions, then the ranunculus were next, and the the tulips. Within 5 years almost all of those were gone, although a handful of tulips lived on for a few more years. The daffodils, Dutch iris, some of the alliums and the Dutch hyacinths are still there.

If you wait too late to plant them, you won't get blooms. That is why I planted in fall----to get them the period of cold weather they need in order to bloom well the following spring. I suspect that in some climates cooler than ours, they plant the ranunculus in spring around the last frost date and then the plants still get plenty of cold exposure and probably bloom in May or June or maybe even July depending on how far north in the USA they're being grown. Even within zone 7, you have some areas that are significantly cooler and have milder weather than Oklahoma has, so in those areas they might plant in spring. I've never tried to plant them in spring---only in fall---so don't know how they'd do from a spring planting.

They're beautiful and I love them when they are in bloom, but their bloom period is really brief in our climate--maybe a couple of weeks. If the heat arrives early (and, for them, temperatures in the 80s are sort of tolerated but they concede defeat when we get close to the 90s), they finish up almost before they start. If I ever plant them again, I'll put them up here closer to the house and give them better care.