The effects on marijuana can last up to

The duration of a marijuana high is highly dependent on several factors, such as chronic (medicinal or recreational) use, polydrug use, etc. But generally, marijuana highs usually last for about 2 to 3 hours. A typical high from smoking marijuana lasts for about 2 hours; orally ingested THC or marijuana can trigger a high that lasts for longer: about 4-6 hours.

Your answer is about 6 hours