Not much
In some places there are, there are strategically-placed benches all throughout the Botanical Garden and some of them offer some really great shade! There may not be too much shade on the pathways, but there are some excellent areas in which there is shade. You could certainly take periodic breaks in the shady areas if you go!
Shade exists but it is hot sunny slopey habitat
Yes, as Moideen mentioned, there are plenty of shady areas throughout, both on paths and over some of the benches. You can always find a shaded spot within a few minutes stroll.
The redwood grove has plenty of shade, but i dont know if that is always open to the public or if it is events only.
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