Wow! What a change! This first season will be quite a learning curve for you.

Filtered vs unfiltered sun- Depends... I'd plant some in both places to learn what works best in your climate, and in your personal gardening space. Soil can differ in separate locations in a yard, too, so experimenting is a good idea the first year before you expand the dahlia beds.

I'm thinking that you are so much closer to the equator that the sun's output might be deceptively 'hotter' in terms of UV and burning, even if the temps aren't way up there... But I don't know. (One Australian grower with extremely hot temps has had success with spraying his dahlias before they bud up with a clay-based sunscreen to keep them from scorching, along with pulse-watering at the roots to maintain a constant level of moisture at the roots.

Most growers I know like to water at soil level, using t-tape or leaky hoses. Some use sprinklers early on, but have to set them under the plants when grown to make sure water gets to the roots. In their active growing cycle, dahlias require ample watering on a consistent basis, like tomatoes.

Some growers here purposely spray their plants in the morning to assist with pest control, but I have no idea what pests you would be dealing with down there. I'm assuming you have a humid climate? Mildew might be an issue if it is always humid.

Hope some of this will help... Please keep us updated on your dahlia adventures! Love to learn what you find works best in Costa Rico!

Thanks for the information Cici.. I really appreciate it! At
least now I have something to start with!

It definitely is a change from where we use to live and I will have to
learn all over again but I think it will be fun at the same time as there are
so many colorful and beautiful plants here.
I’m looking forward to finally being able to plant something other than
Impatients and Hostas! LOL

We are in the mountains at elevation 3500 feet so it’s not
particularly humid and the mid-day temps are between 75-85 degrees. Nighttime
temps are 65 degrees. But as you said,
the morning sun does feel very hot at
times, even though the temperature is only about 70 degrees. So this may cause
an issue for me. :(

The place I decided for planting faces to the east and gets full morning sun, and afternoon sun is filtered through some trees that currently do not have many leaves (it is summer/dry season here) so I think this will work for now. Not sure how it will go when the winter/rainy season comes as the trees will bud out and not sure if the dahlias will get enough afternoon sun at that point. This is our first year in this house so not even sure how our yard changes during the seasons. Everything is going to be a learning experience for me!

I have 3 planted so far, and will visit the garden center again to pick up a few more to finish out the bed. Keep your fingers crossed!