Page 40 - Simply Vegetables Summer 2022

beds with soil of a high organic matter content. Add more organic matter annually either by mulching and or digging in to maintain the soil condition and fertility.
Plan a crop rotation to avoid the build up of pests and diseases which will not be easy to get rid of if they are in the soil. Also aim for all the year round cropping so the tunnel is fully utilised unless you decide to have a fallow period or grow a green manure crop. It will pay to replace the soil in the beds/ borders every 3 to 5 years as the structure
is still likely to deteriorate and cropping decline but monitor it to see. An alternative is to use grow bags and other containers or a hydroponic system like the nutrient film technique. If using containers, ensure they are of a good size or they dry out too quickly.
Tunnel Maintenance
Repair any rips/holes with repair tape promptly to prevent them getting worse, do both sides of the polythene to reinforce the repair and ensure it lasts. Ensure the polythene is clean and dry before fixing with the tape.
In the autumn/early winter clean both inside and outside the tunnel with warm soapy water to which can be added a little bleach or disinfectant to kill any pests and diseases as well as algae. Cleaning both sides of the polythene allows maximum light transmission during the winter when it is most needed. Clean
the doors and any structure
to kill any overwintering
pests. Cover any plants in
the tunnel while cleaning or
move them out. Ensure the
polythene is kept taut and
re-tension if necessary.
Growing
Aim to use the tunnel all
the year round by growing
a range of crops. You can
grow most fruit and vegetables in a tunnel so choose crops you like. You can get early crops like salads or strawberries as well
as the normal summer crops of tomatoes, cucumbers, peppers and aubergines. These can be followed by a late autumn/ winter crop of salad leaves etc.
Which crops you can grow depends to some extent on your location, southern or northern U.K and whether in a frost pocket or exposed area which will reduce the achievable temperature in the tunnel. A tunnel in the southern U.K will be three to four weeks earlier than in Scotland or cooler area.
Sowing and planting is the same as in
a greenhouse or outdoors and the same preparation of forking over, raking a tilth and sowing/planting depths. Apply a general fertiliser before sowing/planting such as Growmore or blood, fish and bone if organic.
It pays to change the soil every three to five years if it is possible as the structure deteriorates owing to the watering and no
weathering effects. If changing the soil is not possible owing to the size of the area or amount of work involved add plenty of organic matter each year usually in the spring prior to the summer planting. If growing in growbags or containers most growing media should produce two crops before it deteriorates to the point where it is better spread over the garden.
Using the tunnel
Spring – sow early salad leaves, carrots, beetroot, radish and plant early potatoes in large potato bags or containers. Start off summer crops that will be planted outside in the tunnel in containers, a propagator
is useful for this if electric is available. Bedding plants and other flowers can
be raised if required. Aim to maintain a reasonable temperature as it can soon reach 25˚C on a warm spring day, open the doors and ventilators if you have them. Night temperatures will be low especially if a frost as polythene does not hold the heat as well as glass. Cover any tender crops with fleece, bubble wrap or even newspaper overnight. Water as required but do not over water as this encourages diseases, monitor the growing media and water individual plants / containers.
If raising plants from seed use the same growing media as for greenhouse growing and the same size and types of pots/
ensure successional sowing are carried out to keep up a supply of fresh produce.
Autumn – sow or plant crops to harvest in early winter and through to the spring, some can be sown in modules and started into growth, so they are growing ready to plant as soon as the summer crops are finished.
It pays to get the winter crop growing in early autumn whilst the day lengths and temperatures are still reasonable. Starting in modules means they can be planted out as semi mature plants and the time to the first harvest is not too long. It is often possible to get a cut of salad leaves before Christmas and then more in the spring. Growth in January and February is usually very slow but it speeds up in March and crops can
be harvested from mid-March to late April when they will be removed.
If planted in late summer into potato sacks/large containers it is possible to have new potatoes for Christmas. The plants make most of there growth through to October and they die back, leave the plants in the bags and harvest on Christmas morning.
Crops sown in the autumn include kale, winter cabbage, lettuce, spring onions, and salad leaves. Also, if the right cultivars are chosen cauliflowers can be sown, pricked out into pots/large modules and then planted outdoors in the spring for an early crop before the cabbage white caterpillars are active. Broad beans are also a good crop to overwinter in tunnels.
Winter – pick any crops ready, ventilate on warmer days to give some fresh
air, reduce botrytis and keep a steady temperature rather than high one day and cold the next or overnight. Water carefully, only as plants require it and carry out early morning so any damp foliage dry’s during the day. When watering give the plants a reasonable soaking around the root area but keep off the leaves. If plants are making growth give a liquid feed.
Empty beds can be dug and organic matter added, clear any rubbish and plant debris; wash and clean the tunnel if not already done as well as washing any pots and containers.
After Christmas and once the days start to lengthen crops of broad beans, early peas, lettuce and salad leaves can be
sown and planted. Strawberry plants that have been chilled by the cold weather
(this breaks the dormancy) outdoors can be brought into the tunnel for forcing for early crops. This should give a crop about a month earlier than the outdoor plants.
If there is a heated propagator in the tunnel early crops can be sown from mid- February/March for planting in the tunnel or outdoors if hardy like lettuce. Herbs like parsley and basil can be grown in the tunnel for early pickings. Lettuce, spinach, chard, beetroot leaves can be sown for an early and quick crop if grown as a come and cut again crop and removed for the summer planting.
You can grow most fruit and vegetables in a tunnel so choose crops you like
containers. Cover all seeds except the really small seeds like celery with growing media or vermiculite. If using a propagator in the tunnel have the temperature set
at 10 to 23˚C depending on what is being grown. For example, 10˚C for lettuce, beetroot etc and 23˚C
for tomatoes, cucumbers, squashes etc. Once germinated reduce the
temperature and move into the general tunnel area, cover with fleece at night if required.
Summer – clear any overwintering/ early spring crops and fork in some organic matter (spread on the surface if no-dig). Add a general fertiliser if required, rake in and plant the crop, water in well and keep moist through the summer. Plant at the same distances as for greenhouse growing. The soil or growing media can soon dry out on a summer’s day, if plants are in containers, they may need watering twice a day on hot days. Open the doors and ventilators every day unless it is cool.
Monitor crops daily whilst watering for pest and disease as these can soon get
out of control if not spotted early. Use appropriate control measures usually a biological control or chemical like soft soap? Hand weed as required as weeds act as host to a number of pests. Liquid feed once a week once the plants are established
If growing lettuce and salad crops
40 Simply Vegetables