Ther are three sizes of Porto. Each Porto is suitable for a certain number of stems. The number of stems that actually fit in the Porto depends on a number of factors:

• Diameter of the stems. Stem diameters differ for differtent flowers.
• Roughness of the stems. This means bulges as in carnations and thorn as in (roses)
• Leaves on the stems. Stems with leaves at the stem ends are thicker.
• Rigidity of the stems. Weak stems are more sensitive to the grips in the opening of the Porto.

In general the number of stems depends on the diameter of the bunch at the stems end. If the diameter of the bunch is 70% of the diameter of the opening in the Porto (plus/minus 20%) the grip fingers will work optimally and the stems will optimally supplied with water in the Porto.

Since stem thickness can vary so much the number stems that actually fit must be determined by experimentation.

Water Capacity

All Portos contain a certain quantity of water which is enough for 2 days at 86° F. This has been tested with large-bloomed Grand Prix roses 27.5". Grand Prix roses are known to be big drinkers; hence the reason this variety was selected for testing. Under test conditions these roses drink around 4 ml per stem per day.

The actual daily water requirements per stem depends on the type of flowers. In general we advise that thin stemmed flowers need less water. The fact that the stems are thinner means a higher number of stems per Porto. The assumption here is that the quantity of water in the Porto will still be enough for 2 days at 86° F.

In practice it's very rare indeed that flowers spend 2 full days being transported in the Porto at 86° F. So, in general the duration of transport can be longer. The cooler it is, the less water will be necessary for the stems in the Porto. It should be noted here that the tests were carried out using slip-covered flowers in a closed box - which means limited evaporation. If the Portos with flowers are transported in open packaging with no covering this will have an impact on the duration of transport. (it will be shorter).