The Ring Culture method is often used where the soil or the base of the greenhouse is not suited to growing plants.
Greenhouse borders are susceptible to soil borne diseases through lack of crop rotation, and lack of natural weathering.
To alleviate the problem one would normally replace the soil on an annual basis.
The floor of the greenhouse may be constructed of an impermeable material e.g. Concrete, Brick or Hardcore.
Ring culture is achieved with the use of bottomless pots or sections of large diameter pipe (rings)
A cheaper alternative (in the short term) would to use purpose made rings made from bituminous paper.
Firstly one must prepare a base for these rings to rest on.
This base can take many forms for example; a brick or timber kerb can be formed on hard surfaces, or a *shallow trench can be dug in the soil.
*Aim for a depth of 100-225mm (4”-9”) the deeper the better.
The resulting void can be filled with a drainage layer which can take the form of clean gravel, spent compost / gravel mixture, or well rotted farmyard manure.
If using the excavation method line the trench with plastic prior to filling to prevent contamination from the soil below.
Puncture the plastic to allow excess water to drain away.
The latter two fillings will act as moisture reservoirs as opposed to the first, which is more of a drainage layer rather than a moisture trap.
The beds and rings should be prepared a couple of weeks before planting.
The rings should be around 200-250mm (8”-10”) in diameter and 250-300mm (10”-12”) high.
These should be laid out at spacing’s to suit the spread of the crop being grown.
For example the spacing would be a little greater for shrub grown subjects such as peppers or aubergines as compared with cordon grown tomatoes.
The rings can be filled with the contents of growbags or home made compost with a potting base fertilizer added.
To economise with the filling, one could fill the bottom third of the ring with a water retentative material such as well rotted farm yard manure and top up with new potting compost.
Part filled with manure
Topped up with Compost
Ready For Plants
Sinking a 4” plant pot into the ring/compost at planting out time will simplify the task of watering and feeding.
This will also prevent washing away compost from the base of the plant and reduce the potential for neck rot.
Feed the plants as recommended for the plant being grown at the dosage recommended by the manufacturer.
The feed mixture should be added to the top of the rings as opposed to the base layer.
At the end of the season remove the plants and add them to the compost heap providing they are not diseased.
If the gravel base method has been adopted rake out all the roots and disinfect the gravel.
This will allow the smell of the disinfectant to disperse prior to using the bed the following season.
It is better to give this treatment at this early stage, rather than waiting to the preparation stage at the start of the following season.
In this way you will deter any pests or diseases overwintering in the bed.
If a soil/manure base has been used, remove this to the compost heap providing it has not become contaminated with any disease.