Successional sowing is a useful technique to use with quick maturing crops and those prone to bolt. Seeds are sown every 2-4 weeks depending on the time of year/season, species and variety. It ensures we have fresh plants to replace those being harvested or that are bolting. In mid summer, when days are warmer and day length is long, plants grow much faster, so more frequent sowings are made. In winter, when growth is slow then the sowing interval can be extended to once a month or even longer. Seeds can be direct sown, sown into seed beds or into modules for planting out as space becomes available. Where space is limited modules are my preferred option as it maximises productivity.
Successional Planting is a progression from successional sowing and refers to the planting of crops one after another. To maximise productivity this would normally be planting immediately after the previous crop. But it can also mean one crop after another with a longer period between each crop. This is quite common in farming where a crop maybe harvested in late summer or autumn with the next crop being sown or planted the following spring.
Successional Cropping is yet another variation on the above two techniques. It normally refers to the annual cropping plan for a given area. For example in many of my commercial greenhouses I grew lettuce that were planted in mid September and harvested in November/December. This was followed by another crop of lettuce that were grown “cold” for harvest from April 1st. Tomatoes were then planted around April 10th to be topped out mid July, with the last fruit harvested by mid September in time for the process to start all over again. The reason I chose this cropping programme was that it suited the quality of the greenhouses I had, heating costs, and aggregate profit margin for the three crops. People with better quality heating systems and greenhouses grew longer season tomatoes with one crop of lettuce. And those with the best equipment grew long season, heated, tomatoes and no lettuce. Interestingly it was frequently possible to make better profit margins with poor quality greenhouses than with good, PROVIDED you reduced overheads and grew premium crops.
Successional cropping on a smaller scale
In the garden we can replicate this principle as indeed I did in my fields. For example I’d plant lettuce in March for harvesting in mid May. This would then be followed by several more crops of lettuce until perhaps October. Or I’d go for early lettuce followed by leeks planted in July and harvested between October and March/April depending on the variety and weather during the season. Another cropping programme would be March planted celery, harvested in July, followed by lettuce or cabbage, leeks, beetroot or other quick maturing crop. Early lettuce could also be followed by Brussel sprouts or a crop of runner beans or courgettes. The variety and mix of crops is huge and often governed by what can be consumed or harvested in the time available. The number of crops that can be grown on an area of land can vary from one per season to as many as 5-6. The maximum number require ideal conditions and can only be achieved in greenhouses where some crops can mature, during mid summer, in a matter of weeks. E.g. lettuce grown in large modules/blocks can go from plant to harvest in 3-4 weeks in mid summer.
It should be noted that a crop rotation is not the same as successional sowing, successional planting or successional cropping. It refers to changing crops grown on a given area so that the same crops are not repeatedly grown in the same area year after year. The technique is based on techniques such as the Norfolk Four Course Rotation which was used to combat pests, diseases and nutrient deficiencies. Modern techniques have largely superseded the need for rotations, though the rationale still has merit in some situations.