Annuals in general require maintenance in planting, and then pulling out a few months later to plant annuals for the next season. There is not a lot of difference between various annuals in this regard.
A sago will turn yellow when soil is cool and poorly drained (soggy) but generally green back up later. The only other suggestion I can provide is to take a photo of the plant symptoms to your County Extension Office to see if they see any other possible causes.
Now is the time to fertilize the bahia by applying 7 pounds of 15-5-10 or a similar blend per 1000 square feet.
The following web site tells how to plant a rose:
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