Have to use your own best guess judgement ......your potting media is very loose ....meaning, not much water will be retained or hang around .....
typically the hotter it is ...the more often plants are watered ....
your weather is unique ...rainfall, heat, humidity, cool & dry all play a part & how plants respond to each .....and you'll need to adjust accordingly
myself ...its been in the 80's & 90's ....I haven't watered with a hose since last year ....why ? ....pouring rain ...last 7 days alone, over 6" of rain ....plants are good and are covered with flower buds
look for signs that the plants need or don't need water .... and ask yourself when was the last time plants were watered and how much ....
If it just poured rain all over them (and depending on daytime temperatures)...then you should skip several days (at least a week) before turning on the water hose .....
one sign, that plants are dry & need water is the plant will have "droopy" leaves ... leaf tips pointing downwards
conversely a sign they are getting all the water they need is that the leaves will be elevated, as if reaching for the sky
watch for yellowing leaves or leaf tips turning brown - plants are either too dry or too wet
another dry sign .....the pot + plant "feels light" ...like a "featherweight"
another wet sign .....watered pots are heavy ...sometimes weighing twice to x3 as much ....
for adenium ...summer is the wet season - water like a tropical
oh yeah -
your leaves are suggesting the plants need fertilizing ...a balanced fertilizer such as 14-14-14 (such as Osmocote)...and a supplementary fertilizer that contains the micronutrients (such as miracle gro all purpose)
