Question
I just want to know which is the altitudinal margin for a nepenthes to be on the intemediate clasification...

I have found some people that say is over 500 to 1300 m, it this correct?  

Answer
Hi Fernando,

The designations highland, lowland and intermediate are arbitrary and should be used only as guidelines for growing Nepenthes.  The general consensus among growers is that 1000-meter mark is the defining factor between highland and lowland.  Intermediate plants are those that straddle that boundary line.

However, there is no agreement as to exactly what an intermediate plant is.  For this reason, we prefer to avoid using these terms and define plants by their elevation.  For instance, N.macfarleni occurs from 1000 - 2000 meters.  Some sources list this plant as highland, while others list it as intermediate.  Consider N. sangiunea, which occur in a similar elevation, yet it is widely considered as a highland.  As of yet, I have not seen anyone reference it as an intermediate, though it can certainly be grown like a lowland Nepenthes with excellent results.

Another example is N. truncata, which occurs from 0 - 2000 meters.  Is this species a lowland, highland or intermediate?  There are highland varieties and lowland varieties.  We grow both the lowland and highland varieties in highland conditions with great results.  We've also heard of growers growing the highland variety in lowland conditions with equally great results.

What we regard as intermediate plants are those plants that can be grown either in highland or lowland conditions, not where on the mountain it occurs.  In general a highland plant needs cool nights (45?- 65癋), while lowland prefers warm nights (above 70癋).  An intermediate plant will grow fine in either condition.  This is why we state, "Cool nights helpful, but not required," or "Tolerant of cool nights, but not necessary."  If you see these statements, it is in reference to plants that are commonly regarded as intermediate.

So use the terms highland, lowland and intermediate as guidelines.  The elevation status of each plant will further guide you to whether a plant requires cool nights or warm nights, or whether it is tolerant of either conditions.

Good growing!
Jacob Farin