Tips & Advice

Plant Bag Volumes… HELP!

Man with Plant Bag looking confused

Why does my Plant Bag look smaller than I thought it would?

This is a common question we receive regarding the smaller sized Plant Bag volumes and sizes.

Sometimes, customers are surprised when they receive some 1 litre or 2 litre bags, expecting the bags to look bigger. Here are a few points to consider that may help you choose the right sized bag.

PERCEPTION CAN BE INFLUENCED BY MARKETING

Large companies in the food and beverage industry often use marketing strategies to make things appear bigger and better than they really are – after, that’s their job! When growers receive a 2 litre container, they are expecting it to look like a milk container in size. These bottles are designed with curves, indents and handles or may have a taper at the top (and even the bottom). All of these things effect the our perceptions of volume. For instance even a 9 litre household bucket can have a taper and different indents that can make the bucket appear bigger. In addition to this, consumer liquid containers are rarely filled to the top.

We find it is mostly the smaller sized bags that have people scratching their head! The The perception evens out as the bags increase in size.

As a side note, for many decades in Australia (where many pots are manufactured), the unit of measurement for a Plant Pot is the measurement across the top of the Pot (Diameter) – for example a 200mm pot. 

Typical juice/Milk Container
Typical juice/Milk Container

For some reason however, in both New Zealand and Australia, the industry instead measures a Planter Bag in volume, or in terms of how many litres of mix it holds, or how many ‘PB’ the bag is (see explanation in next paragraph). 

This is probably because several bags that have the same diameter will hold a different volume depending on the height of the bag. Our 2.5 Litre, 4 Litre, 5 Litre tall, 6 Litre tall and 7 Litre tall bags, for example, all have a similar diameter, but they just get taller. 

2 Litre Plant Bag

What does PB2 mean?

The standard measurement for Planter Bags in New Zealand is the PB number, or ‘Pint Bag’ number. Each PB is a unit measuring Pint Bag and is the equivalent to approximately 570ml in volume (1 pint).

So PB2 is a bag that would contain 1.15 Litres. It is more of a rough measurement and you’ll find a PB1.5 might be used to describe a 1 litre bag etc.

Volume comparison – 75L bag vs 50L p0t

The below picture has a 50 L pot next to a 75 L bag. I’m not going to pretend that I didn’t super-impose the pot into the Bag picture 😂 so is obviously only an example. In real life, the appearance of these 2 containers is actually very similar when you look at them. The main difference is in the name! The pot is wider at the top than it is at the base (taper) and it holds much less mix compared the bag which has straight sides.

Let’s look at the measurements of both the bag and the pot in the example picture;

75 Litre woven bag – Diameter 460mm x Height 460mm. (Inside Diameter 460mm, Base Diameter 460mm)

480mm (50L) Pot – Diameter 480mm x Height 400mm. (Inside Top Diameter 435mm, Base Diameter 380mm)

We hope that helps a bit when you are next choosing your Plant Bag Size. Healthy gardens to you all!

Volume comparison - Bag vs Pot
Volume comparison - 75L bag vs. 50L pot.
Poly Planter Bag