Polytunnel Succession Planting Plan 2021

Regular readers will know that I included my outdoor garden succession planting plan in one of our January emails. I also said I would follow with my polytunnel plan if anyone was interested and have had a number of emails requesting same so am happy to include it today. Apologies to anyone who was holding their breath.

I make the point that while I would consider myself a pretty good outdoor gardener I am certainly not a polytunnel expert. I have a good size outdoor garden so mainly use the tunnel to grow 'exotics' like Aubergine, chilli, sweet peppers, tomatoes, cucumber and courgette. I also try to make sure I have some overwintering crops on the go for winter leaves or early spring harvests. My efforts are probably pretty ham fisted in comparison to true polytunnel growers so please don't see the following as the definitive list, it's just what I am doing this season.

Tunnel Space I probably have an odd size growing space as I use a portion of a much larger tunnel that also doubles as a video studio and, currently, a boat yard. The beds in the plan cover an approx 12 metre length and are all 1.2m wide. The partitions in the beds are not relevant to what's growing in them, I was just using up waste timber from the warehouse.

In a standard tunnel you are more likely to have 3 rows of beds with the centre one being used for the climbing plants as it is the tallest point and is under the crop bars. A centre climbing bed also makes it easier to harvest each side of tall crops. My plan is just to show you sucession, I wouldn't copy the tunnel layout unless you have a high sided tunnel.

The general gist of it Warm climate crops like tomatoes, chilis or cucumbers have a relatively long growing season, they are planted in May (but sown much earlier) and aren't cleared out until October. In order to take advantage of the other 6 months of the year I try to get an early spring crop in before the big guns are planted and follow with an Autumn/overwinter crop.

Please be aware that for intensive cropping like this, sometimes with 3 crops in 12 months from the same space, we need to pamper our soil. I would add 2 dressings of well rotted garden compost per year and need to add supplementary feed for the big fruiting plants.

The trick to intensive planting A fertile soil is the cornerstone of intensive planting but you also need to do your planning and have tray or pot grown plants ready to go when space becomes available. A normal size vegetable seedling 'plug' plant (you can see some in the background in the photo above) needs to be either planted out or potted on in 4 weeks so you would need to sow your seeds 4 weeks before the crop you are replacing is harvested.

Some plants (e.g. tomatoes or chillies) need to be sown early in the season but can't be planted in 4 weeks (either because it is too cold or there is something else in the bed) and will need to be potted on, sometimes more than once, before being planted in their final positions. The tomato plants in the photo were started in seed trays, transplated to 9cm pots (left) before being potted on to larger 19cm pots (right). They are finally planted in the beds 3 months after sowing. The main reason for this is because it is too cold to plant them until early May but I am also buying time if the previous crop isn't quite ready to come out. As an example look at bed 2 in section A below; the crop before tomato is garlic (planted the previous October) which, depending on how the weather works out may need a couple more weeks to bulk up.

Interplanting In many cases I don't need to wait for the beds to be clear before planting my follow on crop. The image above shows winter salad seedlings planted last Autumn in the tomato beds. You can only see the tomato stems because I have removed most of the leaves to ripen the fruit. The salads can be growing away while the last tomatoes ripen before the vines are removed in early November, the tomatoes are taking very little from the soil at this stage so are not competing with the salads for nutrients.

The same method can be used at the other end of the cycle. If my spring garlic needs to grow on a bit more I can take out one or two and put in my tomato plants. They can grow together for a few weeks before the tomato roots spread out and need to take nutrients from a wider area.

The Plan I hope the following plan makes some sense. As you see above, I have listed what is in my beds now above each bed, the summer crop is listed in the circle and the follow on autumn or overwinter crop in the box below. It all looks pretty long winded with some repetition but I have listed each bed in detail below so you can see when crops come in and out. OK? Here we go:

Section A

Bed 1 1.8m x 1.2m Current crop: Garlic planted last October, will be harvested in mid May or early June depending on size. Summer Crop: Climbing French beans sown in pots in early April, planted in beds after garlic in May. Overwinter/early Spring Crop: Winter leaves may include Oriental salads, lettuce, endive, spinach, Oriental spinach, chard, claytonia or corn salad. Plants are sown 6 cell trays in late August and planted in mid October when the beans come out.

Bed 2 1.5m x 1.2m Current crop: Garlic planted last October, will be harvested in mid May or early June depending on size. Summer Crop: Tomato sown in mid February in trays, potted on twice and planted in mid May. Harvest until late October. Overwinter/early Spring Crop: Winter leaves may include Oriental salads, lettuce, endive, spinach, chard, claytonia or corn salad. Plants are sown 6 cell trays in late August and planted in mid October around tomatoes.

Bed 3 1.5m x 1.2m Current crop: Early carrots ('Amsterdam forcing', must be a suitable early variety) sown in early February, harvested as baby/medium sized carrots in late May. Soil needs to be at least 10˚C for carrots to germinate so cover beds with black plastic to warm, if very cold delay sowing. Summer Crop: Cucumber sown in 6 cell trays mid April and potted on before planting in late May. Overwinter/early Spring Crop: Winter leaves may include Oriental salads, lettuce, endive, spinach, chard, claytonia or corn salad. Plants are sown 6 cell trays in late August and planted in mid October.

Bed 4 1.2m x 1.2m Current crop: Early carrots ('Amsterdam forcing', must be a suitable early variety) sown in early February, harvested as baby/medium sized carrots in late May. Soil needs to be at least 10˚C for carrots to germinate so cover beds with black plastic to warm, if very cold delay sowing. Summer Crop: Melon sown in 6 cell trays mid April and potted on before planting in late May. Overwinter/early Spring Crop: Broad beans sown in early November in trays and planted in December, harvested the following April/May before the summer crops go in.

Bed 5 1.8m x 1.2m Current crop: Strawberries planted in February from pots kept outside for the winter, will crop May to June. New runners will be potted and stored outside until the following February. If you don't have a bed free for strawberries, they can also be grown in large pots but must be moved outside in summer. The advantage of tunnel growing is you will get an earlier crop than you would outside. Summer Crop: None Overwinter/early Spring Crop: Beetroot sown in early June in trays and planted in late June, harvested from December till the following spring.

Bed 6 1.8m x 1.2m Current crop: Chitted first early potatoes planted in early February for cropping in May. Summer Crop: Sweetcorn sown in 6 cell trays in early May for planting in early June. Harvest Sept-October. Overwinter/early Spring Crop: Florence fennel sown in late July and planted in early August between the ripening sweetcorn, will grow on once the sweetcorn is harvested in October. N.B. I have had success with this in some years and not others. Harvest over winter.

Section B

Bed 7 1.8m x 1.2m Current crop: Purple sprouting broccoli sown the previous June, grown in pots until planted in beds in early September. Did not produce heads over winter but an early crop staring to form now. Summer Crop: Tomato sown in mid February in trays, potted on twice and planted in early May. Harvest until late October. Overwinter/early Spring Crop: Winter radish e.g. 'Mooli', 'Watermelon' or 'China Rose' sown around the tomatoes in September. Tomatoes are removed in mid/late October.

Bed 8 1.5m x 1.2m Current crop: Spring Cabbage sown in early August in trays, potted on 4 weeks later and planted in mid October. Harvest in April/May. Summer Crop: Aubergine and sweet pepper sown in mid February in trays, pricked out and potted on twice before planting in mid May. Harvest September/October. Overwinter/early Spring Crop: Early carrots ('Amsterdam forcing', must be a suitable early variety) sown in late January/early February, harvested as baby/medium sized carrots in late May. Soil needs to be at least 10˚C for carrots to germinate so cover beds with black plastic to warm, if very cold delay sowing.

Bed 9 1.5m x 1.2m Current crop: Mangetout pea sown in pots in early October and planted out at the end of the month. Harvest in April/May. Summer Crop: Squash including butternut squash and 'Uchiki Kuri' sown in 6 cell trays and potted on before planting in mid May. Overwinter/early Spring Crop: Chitted first early potatoes planted in early February for cropping in May.

Bed 10 1.5m x 1.2m Current crop: Winter leaves may include Oriental salads, lettuce, endive, spinach, chard, claytonia or corn salad. Plants are sown 6 cell trays in late August and planted in mid October, will crop slowly all winter with a burst of early spring growth before the making way for tomatoes. Summer Crop: Tomato sown in mid February in trays, potted on twice and planted in early May. Harvest until late October. Overwinter/early Spring Crop: Broad beans sown in early November in trays and planted in December, harvested the following April/May before the summer crops go in.

Section C

Bed 11 1.8m x 1.2m Current crop: Winter leaves may include Oriental salads, lettuce, endive, spinach, chard, claytonia or corn salad. Plants are sown 6 cell trays in late August and planted in mid October, will crop slowly all winter with a burst of early spring growth before the making way for tomatoes. Summer Crop: Tomato sown in mid February in trays, potted on twice and planted in early May. Harvest until late October. Overwinter/early Spring Crop: Early carrots ('Amsterdam forcing', must be a suitable early variety) sown in late January/early February, harvested as baby/medium sized carrots in late May. Soil needs to be at least 10˚C for carrots to germinate so cover beds with black plastic to warm, if very cold delay sowing.

Bed 12 1.5m x 1.2m Current crop: Winter leaves may include Oriental salads, lettuce, endive, spinach, chard, claytonia or corn salad. Plants are sown 6 cell trays in late August and planted in mid October, will crop slowly all winter with a burst of early spring growth before the making way for tomatoes. Summer Crop: Chilli pepper sown in mid February in trays, pricked out and potted on twice before planting in mid May. Harvest August to October. Overwinter/early Spring Crop: Garlic cloves planted in October, will be harvested the following May.

Bed 13 1.5m x 1.2m Current crop: Beetroot sown in trays early last August and planted in September. Small beets have been harvested since December, they are starting to bulk up again now the weather has warmed. Summer Crop: Tomato sown in mid February in trays, potted on twice and planted in early May. Harvest until late October. Overwinter/early Spring Crop: Garlic cloves planted in October, will be harvested the following May.

Bed 14 1.5m x 1.2m Current crop: Broccoli calabrese sown late last August and planted in early October, harvest January/February. N.B: I have not seen this recommended anywhere else but I tried it last year to see what happens, producing very welcome tasty broccoli heads now, I just had some for lunch! Summer Crop: Courgette sown in late March/early April in 6 cell trays and planted in May, can also be sown in June for a late harvest if you have no space available. Harvest throughout the summer. Overwinter/early Spring Crop: Mangetout pea sown in pots in early October and planted out at the end of the month. Harvest the following April/May.

That's it for now, I will see you next week!