Ranunculus tubers should be planted in October or November. Contrary to
some, the dry tubers do not need to be soaked in water before planting.
There should be some bone meal under the tubers but not touching them.

I would leave them in the ground. The survival rate is better than if
you remove them.

As long as you don't plant directly on top of a dormant tuber, you can
plant summer annuals near them. When the annuals die, cut them down;
don't pull them out, which might pull out ranunculus tubers that have
become entangled in the annuals' roots.

My garden is planted with perennials, bulbs, shrubs, subshrubs, and
ground cover. I have ranunculus in my rose bed along with freesias and
narcissus. The bed also contains evergreen daylilies, narcissus,
cuphea, primroses, low Camellia sasanqua, and blue fescue. The back of
the bed has dwarf Burford holly. One end has a clump of pink Penstemon.
The entire bed is covered with pink clover (Persicaria).

The ranunculus, freesias, and narcissus bloom only in the late winter
and into the spring, before the roses and daylilies bloom. When they
die down and go dormant, the rest of the plants in the bed provide more
than enough interest.

--
David E. Ross
Climate: California Mediterranean
Sunset Zone: 21 -- interior Santa Monica Mountains with some ocean
influence (USDA 10a, very close to Sunset Zone 19)
Gardening diary at http://www.rossde.com/garden/diary