Color Change on value threshold

Greetings All,
I am working on a simple chart to graph numbers between -2 and 6.

I would like any value less that 0 or more than 5 to appear in red, all the other values in blue.

Is this possible? If so could you point me an example?

Thank you for your help!
Dave

Gotit - I want to do the same thing. A graph of temperature in my greenhouse. At 55F a space heater turns on and I want to have temperature line to be green when above 55F and red below 55F.
+--------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+--------+--------------+------+-----+---------+----------------+
| id | mediumint(9) | NO | PRI | NULL | auto_increment |
| ts | timestamp | YES | | NULL | |
| ghtemp | float(4,1) | YES | | NULL | |
| ghhumd | float(4,1) | YES | | NULL | |
| ghsump | float(4,1) | YES | | NULL | |
| ostemp | float(4,1) | YES | | NULL | |
| oshumd | float(4,1) | YES | | NULL | |
| misc | int(11) | YES | | NULL | |
+--------+--------------+------+-----+---------+----------------+

"misc" will be 00000 heat off, 00001 heat on. Plot create needs $plot>SetDrawBrokenLines(TRUE);
which allows for the line to "------- _-----------" where data[8] thru data[14] is NULL. (an aside)

For testing because it's 4 deg outside right now I used $data[$n] to make it work.

In the mysql while fetch_row

if ($n > 100 && $n < 200)
{
$data[] = array($h, $row[2], $row[3], $s, $row[5], $row[6], 32, $row[2]);
} else {
$data[] = array($h, $row[2], $row[3], $s, $row[5], $row[6], 32, NULL);
}

and $plot->SetDataColors(array( 'DarkGreen', 'blue', 'brown', 'YellowGreen', '#aaaaaa', 'black', 'green', 'red'));
and my graph is:
gggggggggggggggggggggrrrrrrrrrrrrrrrrrrrrrrrrrgggggggggggggg ______gggggggggggggg
the blank part is where I updated the temp to NULL.

and Who's on First