I use a Tabloid, its the right size for a 2″ diameter, 4″ tall, pot. Lay out a double sheet flat.
Fold the top-to-bottom (not side-to-side). It doesn’t have to be done tidily, the edge with the fold will be the “clean” edge we use.
Wrap around an aerosol can. Keep the folded edge towards the top, and the rough “open” edge an inch or two off the bottom of the can.
Roll the newspaper around the can …
You can slide it up/down the can to adjust, and once you have the correct size mark the can, or make a mental note of some writing/logo on the can as the correct marker for the rest of the pots you are going to make.
Tuck the loose end under the can, this takes care of any untidiness in the bottom edge, if your fold was not precise etc.
I stand the lid of the can on the table, and press the bottom down onto it, which makes a tight base (that makes it easier to get the pots to stand upright in the tray)
Base is completed!
The finished pot is just a tube with the bottom folded in. Fill with compost, arrange in a tray (I use a seed tray for up to 15, and a 60cm (2 ft) square gravel tray for 50 – 60 – but beware that is then quite heavy to carry). The gravel tray has no drainage, so be careful not to flood it, the newspaper sitting in water will fall to bits, but other than that normal watering won’t cause it to disintegrate (which may be surprising the first time you use them)
A 60cm (2 ft) square gravel travel with newspaper pots containing Parsnip seedlings; get them outside to harden off as soon as the seed leaves are showing, and get them into the ground before the first true leaf shows (because by the time the first true leaf shows the tap root is likely to be out of the bottom of the pot and when that happens it is much more likely to “fork”). There are about 3 weeks from germination to true leaf appearing, so just enough time to harden off and plant out before first true leaf appears.
Sweetcorn in Newspaper pots
To plant out make a hole (I use a bulb planter to make the hole deep enough) and drop the pot in – do not remove the newspaper, it will rot down, but it is important that the plants are well watered before planting; I also water the planting holes prior to planting, so that there is plenty of moisture below the young plant, to encourage the roots to go downwards (this applies to any such planting, not specifically newspaper pots, but it does ensure that the newspaper is saturated and the roots can get through it easily)
The ring of newspaper above the soil must be removed, otherwise it will act as a “wick” and dry out the pot underground.