no cant exclude on a product by product basis.
the idea is to create a category column in your cart.
in the add to cart button, set the value of the category to be "plants" for items that should be charged based on the plants postage scheme and "stationary" for items that should be based on the postage scheme.
if you have items that not be charged any postage, then leave the category for those items blank.
then configure the rules as such (where yourCartName is the name of your eCart object:
Name: plants up to 10
Triggers:
Custom condition:
WA_eCart_ConditionalTotal(yourCartName, "TotalPrice", "category", "plants") < 10
Calculation:
Flat Rate: 7
Name: plants 10 - 15
Triggers:
Custom condition:
WA_eCart_ConditionalTotal(yourCartName, "TotalPrice", "category", "plants") >= 10
Custom condition:
WA_eCart_ConditionalTotal(yourCartName, "TotalPrice", "category", "plants") < 15
Calculation:
Flat Rate: 13
Name: stationary to 16
Triggers:
Custom condition:
WA_eCart_ConditionalTotal(yourCartName, "TotalPrice", "category", "stationary")< 16
Calculation:
Flat Rate: 5.50
Name: stationary 16 - 32
Triggers:
Custom condition:
WA_eCart_ConditionalTotal(yourCartName, "TotalPrice", "category", "stationary") >= 16
Custom condition:
WA_eCart_ConditionalTotal(yourCartName, "TotalPrice", "category", "stationary") < 32
Calculation:
Flat Rate: 7.50