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Lesson:

Skills for Growing

Succession and rotation

Succession planting could get very complicated and is often made too difficult. Fortunately, however, it does not need to be – you mainly just need to familiarise yourself with the best sowing, transplanting and finishing times for each vegetable.

The six photos below, showing the same bed over two years, are to give a sense of progression of plantings. They grow slowly then fast, and finish before you know it, which is when you need seeds or plants ready (or even before that, if you interplant).

A mixed planting in April, three weeks after the plants were set outside, with carrots sown at the top

By 21st May, there is strong growth of spinach, spring onion, turnip, broad bean, lettuce, coriander, dill, cabbage and rocket, with violas in front

Just six days later, and growth is now very rapid with the carrots looking stronger; overwintered spring onions at the end

Savoy cabbages followed the mixed planting – they were sown in June, planted in July and this is February

The following year in early June, the Savoy cabbages were followed by courgettes, with more cabbage and parsnip beyond

By early November, there are spring onions transplanted after courgettes, and cabbage after cabbage; the parsnips are yet to crop

Succession timings

I want to clarify sowing for succession, through the groupings and table shown below. The aim is to maximise your success, through every sowing being at a propitious time.

Use the groupings alongside the finish dates in the table, to help you to plot and plan what could follow a planting whose harvests are ending. Keep your soil healthy and harvests plentiful, through plants growing all the time.

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Dates for transplanting three- to five-week-old seedlings

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GROUP 1 – TRANSPLANT DATE LATE MAY TO MID-JUNE:

Beans – dwarf, French and climbing; beetroot; broccoli; Brussels sprouts; carrots; celery; chard; courgette and summer squash; cucumber; kale; leaf beet; leeks; lettuce; parsnips; salad onion; squash for winter (asap); swede; sweetcorn (asap)

GROUP 2 – TRANSPLANT DATE MID-JUNE TO MID-JULY:

Beans – climbing (asap) and dwarf French; beetroot; broccoli; Brussels sprouts (asap); carrots; cauliflower; celery; chard; chicory; courgette (asap); cucumber; endive; kale; leaf beet; leeks; lettuce; salad onion; swede

GROUP 3 – TRANSPLANT DATE MID-JULY TO AUGUST:

Broccoli; celery (asap); chicory; Chinese cabbage; chard; endive; Florence fennel; kale; kohlrabi; land cress; leaf beet; Oriental leaves (including mibuna, mizuna, mustards, pak choi and tatsoi); salad rocket after mid-august: spinach; turnips; winter radish; chervil; coriander; dill

GROUP 4 – TRANSPLANT DATE EARLY SEPTEMBER:

Claytonia; Florence fennel (mild areas only); kale for salad leaves; corn salad / lamb’s lettuce; land cress; Oriental leaves (including mibuna, mizuna, mustards, pak choi and tatsoi); radish; salad rocket; spinach; chervil; coriander

GROUP 5 – TRANSPLANT DATE LATE SEPTEMBER TO EARLY OCTOBER:

Cabbage, lettuce and onions – all for spring; chervil; Claytonia; corn salad / lamb’s lettuce; wild rocket

Outliers are garlic to plant from mid-September and through autumn, and broad beans to sow in late October to early November, depending on climate.
Exceptions are direct-sown carrots, garlic and parsnip.

Succession guide

Vegetables not mentioned as first plantings in the table, below, either carry on growing almost all season after being sown or planted (celeriac and parsnips), or are best grown as second plantings. Examples of the latter are Brussels sprouts, chard, chicory, kale, leeks and swedes. You can also follow climbing beans and squash with garlic or green manures.

Choosing second plantings

It can sometimes be less obvious what to plant as a following vegetable, compared to a first planting. There is also a lot of contradictory folklore – I once had a visitor tell me that the pak choi I was planting after clearing soybeans ‘will fail, because nothing likes to grow straight after soybeans finish’.

It was the first summer I had grown soybeans so I had no evidence that she was wrong, but continued planting for sure, and the pak choi grew marvellously.

I strongly urge you to resist the naysayers; they are numerous and have a negative mindset of supposed pitfalls and problems lurking behind every new idea. Follow your hunch, not theirs.

Here, however, are examples of potential problems that can occur if you choose an out-of-season vegetable for a second planting, or sow it at a bad time. These problems will not happen if you follow my suggestions in the table.

Spring / salad onions sown in summer (not spring) risk getting grey mould / downy mildew on their leaves and, if you see it, are best harvested soon.
Peas and broad beans sown in summer crop far less in autumn, compared to summer harvests from spring sowings.
Lettuce sown in July to August give fewer harvests because they rise more quickly to flower. They also suffer more mildew, compared to the harvests from spring sowings.
Spinach sown in May to July risks bolting and therefore produces fewer harvests. It is best sown in late summer, after its flowering time has finished. At Homeacres, I find that 10th August is a good sowing date, to ensure steady growth until spring.
Florence (bulb) fennel is like spinach: it’s likely to flower from sowing in late spring to early summer. My best sowing date here is late July, for fat bulbs in autumn.

Summer sowings on 19th September – chicory for radicchio left, endive centre, and spinach right, interplanted between lettuce in late August; these vegetables would not crop for long if sown in spring

Plant families

Vegetables are related to each other, and there are a few main families that I urge you to familiarise yourself with. This will help you to understand how each vegetable grows, when to sow, and which pests and diseases are likely.

Rotation of plant families – how necessary is it?

When following each planting, does rotation matter? Generally, it feels sensible to make second plantings from a different family, since there is a range of plant families to choose from. For example, carrots could be followed by brassicas, onions by chicories, potatoes by leeks, or beetroot by celery.

However, it is not essential, and I sometimes plant, say, broccoli after broccoli. You may happen to like vegetables that mostly come from one or two families, in which case you will not be working out a rotation!

An exception is under cover, where space is especially suited to a narrower range of plantings. There is not much point erecting a greenhouse or polytunnel to grow summer kale and beetroot which do fine outside, but the extra warmth increases the growth and health of warmth-loving plants, many of which are related – tomato, aubergine and pepper, for example.

These photos illustrate my minimal rotation under cover. Minimal rotation is more likely to succeed where soil health is good, and no dig helps a lot.

SUMMER HALF

Sakura F1 tomatoes have excellent flavour; this is the third year, out of six, of tomatoes in my greenhouse – they are in the same bed and soil as blighted tomatoes from the previous year

15th August, in the seventh consecutive year; this harvest was 8.3 kg / 18.3 lb of beef tomatoes and 3.7 kg / 8.2 lb of aubergines, one week since the previous pick

21st August – just six days later and another harvest awaits; here it’s peak time for beef tomatoes ripening

WINTER HALF

14th November 2018 – the sixth consecutive planting of winter salads in my greenhouse includes lettuce and brassicas, just one month after transplanting

3rd April 2019, and it’s –3°C / 27°F outside; salads planted in October have been picked many times, and will finish by May

12th November 2019 – the seventh consecutive year of winter salads; we have picked them once alread

Succession and rotation with mixed plantings

My trial beds, dig and no dig, are always full between March and early November. We grow ten or more different vegetables at the same time, twice a year. They grow close together and in a mixed-up fashion, based on what works well in terms of space between plants and length of growing time.

I practise what one could call a mini-rotation within the same year, by following plants of one family with plants of a different family. The positions of new plantings in the following spring are not governed by those of the previous year.

The main consideration is spacing correctly, and sometimes you follow a space-demanding vegetable, like a potato, with salads or beetroot, which need less space. If this is the case, simply plant an extra row.

26th May 2021 – the first plantings are potatoes, peas, cabbage, carrots, onions, shallots, lettuce, beetroot and spinach ; the top photo on p.195 shows when these plants went in the ground (the radish and turnips have already been harvested)

The same bed four months later with its second plantings of summer: cabbage, endive, beetroot, celery, leeks, French beans, mustard (third planting after carrots), and cucumber with Florence fennel

An example of no rotation

In order to see the results of no rotation, I plant the same vegetables in the same place every year, as part of the Three-Strip Trial. Plantings on one of the trial’s six beds are always broad beans followed by cabbage, and on another bed are always potatoes followed by leeks.

Plant growth and harvests continue to be good on both beds, even after six years of this continuous cropping. I imagine that soil health helps plant health and vigour.

In 2019, I had a potato plant with blackleg which came from one seed potato (more information on following page). I harvested it as soon as seen, and there was no residual infection in 2020; I had planted with homesaved seed.

September 2021 – brassicas and leeks, also in the seventh year of being grown in the same beds

Disease and rotation

If you are unlucky enough to take over an allotment where there is either clubroot disease of brassicas, white rot disease of alliums, or potato blackleg, you will need to rotate these plant families.

Late blight (Phytophthora infestans), on the other hand, does not persist in soil, because blight spores need living material to survive.

No dig helps to restore soil health, making these diseases less likely and less severe, but some rotation will still be necessary.

CLUBROOT (PLASMODIOPHORA BRASSICAE) – A disease that causes brassica roots to develop swollen galls, and which lingers in soil for several years. Very few people have experience of it outside allotments that have been mismanaged through over-cultivation and lack of added organic matter, meaning the soil is depleted, unhealthy and more prone to disease.
WHITE ROT (STROMATINIA CEPIVORA) – White rot of allium is a fungus that becomes active when soil is warm, above about 20°C / 68 °F. In late spring to early summer, you suddenly notice onions and garlic falling over with their roots being eaten by a white fungus. Leaves go yellow and plants cannot be saved.
POTATO BLACKLEG (PECTOBACTERIUM ATROSEPTICUM) – A common bacterial disease of potatoes, causing plant stems to go black and slimy. It is mainly transmitted through seed potatoes and increases in certain conditions, such as a cool and damp spring. If the plants are not removed quickly, tubers will start to rot. If you harvest at this point, you can still use the potatoes, although they will be small. There is a very small chance of the disease remaining in the soil from previous infections, and any substantial amount of blackleg would make rotation worthwhile.