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Growing TutorialsPolytunnel Growing

May 5th, Planting tomatoes, chillis and cucumbers in the polytunnel

Tractor in polytunnel

Tractor in polytunnel

I made a vow to myself last week that I would go at least a month without including a photo of my tractor in these emails. As you see above I have failed already but, to be fair, that’s a really nice picture. Seeing as I won’t be allowed to talk about it for a while I might as well tell you it has all new track rod ends and a new hydraulic filter fitted and is going like a clock.

The reason it was in the tunnel in the first place is I was adding more raised beds to give me space for all the tomatoes and peppers I have been growing and were starting to get too big for their pots.

Salad leaves and basil in polytunnel

You can see the new beds I featured in the mail a couple weeks ago are already productive with some butterhead and oak leaf lettuce growing away nicely. I have started picking some of this by removing a few outside leaves and letting the heart grow on; you can keep a lettuce plant going for weeks by doing this instead of harvesting the whole head.

The little fellas between the lettuce and beans are basil seedlings, I put in quite a few as everyone in the house seems to be addicted to expensive pesto and figured we might as well make it ourselves.

Garden soil polytunnel

You may be able to see quite a few weeds between the spinach and the beans in the top image (try not to look at the tractor) which are making a nuisance of themselves by popping up all over the place. This is because I used soil from my field which contains a buried seed bank bank of thousands of weed seeds all patiently waiting for their day in the sun. You might remember I layered this soil on the bottom of the beds to keep the weed seeds buried but then ignored my own advice and mixed it all up with the manure and compost. I won’t be making the same mistake again.

Above you can see the nice dark brown stuff from my old polytunnel which I used more of this time, it’s relatively weed free and has been pampered over the years so should be pretty fertile. This time I used a shallower layer of field soil covered with polytunnel soil enriched with well rotted manure mixed into the top few inches.

Tabasco chilis plant in polytunnel

Above you can see a freshly planted tabasco pepper looking happy in it’s new home. I had some mixed results with the pepper seedlings I sowed in March with some doing very well and others really struggling. I had leaves with yellow patches which would hint at nutrient deficiency (likely magnesium) but they were all grown in the same compost albeit from separate bags. If you are using organic compost be aware it does ‘go off’ quicker than compost with man made nutrients so is best bought fresh every year. This may have been the problem.

Peppers are tall and relatively unstable plants so I will be supporting them with a short length of cane when my plants reach 20cm tall. When the plants approach around 30cm I will pinch out the growing tips to encourage them to get more bushy and bear more fruit. Large chilli plants with a heavy crop may also need further support with a few more canes depending on the variety, we’ll see how they progress.

Tomato plant roots in a pot

The photo above shows my girly little hands and a tomato plant that should have been removed from its pot over a week ago; you can see the roots just starting to panic, looking for a way out.

Obviously one of the reasons for the delay is I had to get the beds ready but in my area May is also the earliest I can plant tomatoes in their final positions (they have been own a heat bench until now). The weather has been so good recently with full days of sunshine warming the tunnel that the tomatoes were ahead of where I expected them to be.

The one in the photo isn’t too bad (there were worse) but if roots have become constricted in a pot it is best to gently tease them out with your fingers to encourage them to grow out and away from the plant.

Tomato plant support

Oars
I am supporting my tomatoes in the same way as the French beans in the previous mail by burying a length of twine under them and tying to a support above. Nautical types will instanly recognise my clever ‘jury rigged’ support as an oar (it has a crack in it) which I suspended from the main hoops using tek screws and twine.

Tek Screws
If you have never used tek screws before they are a revelation; they have a cutting bit on the tip end and will go straight into steel by drilling their own pilot hole before burying themselves in the metal. They are one of the few things in life that consistently perform far better than expected.

Twine tomato plant support

As I did when potting on my tomatoes to larger pots, I have planted deep and covered the lower part of the stem up to the first set of leaves. As we all now know this builds a more extensive root system as the new roots will grow from the buried stem.

Mycorrhizal Fungi
Stupidly I forgot to take a photo but I also added some mycorrhizal fungi to the planting hole as their fungal networks will help bring nutrients to the tomato roots. Mycorrhizal networks exist in undisturbed soil and form a symbiotic (benefits both parties) relationship with plants who feed them sugars in exchange for minerals mined from the surrounding soil. Interestingly, it has also be shown that tomatoes grown with good mycorrhizal networks put up a stronger defence against tomato blight as the fungi induce the production of defence related enzymes.

As my beds have just been filled with ‘disturbed’ soil, the mycorrhizal networks have been broken up. By adding fungi at planting time I am getting the networks back up and running so they can help feed and protect my tomato plants. Mycorrhizal fungi is available (from us of course) in granular form or as a ‘biscuit’ made specifically from tomatoes which is placed under the roots when planting out.

View Rootgrow Mycorrhizal Tomato Starter

Tomato plant seaweed poultry manure feed

You can see here how I have coiled the twine around the tomato stems. The twine tied to the oar above uses a slip knot as the twine can get overly tight as the tomato grows and the stem thickens so it may need to be loosened a little. The tomato plant is easily trained by winding the supple tip around twine whenever there is enough new growth to do so.

Tomato Feed
You can also see a handful of seaweed/poultry manure in one of my grubby paws which I have mixed in around the planting hole to give a head start. I will also be feeding with a liquid feed high in potassium once the vine flowers and begins to set fruit. It is then recommended to feed every 2 weeks, I won’t be feeding as much as the soil is very fertile but if growing in more confined spaces like grow-bags I definitely would.

View 'Seafeed' Seaweed & Manure Plant Feed

removing tomato side shoots

Side Shoots
Tomatoes grow in a vine (indeterminate) or bush (determinate) habit. The vast majority of homegrown tomatoes are vine varieties as they have a higher yield over a much longer season but if you want a lot of tomatoes at the same time (e.g. for making tomato sauce or growing in a low cold frame), a bush variety is useful.

Bush tomatoes may need some support when fruiting but need very little maintenance. Vine tomatoes need to be supported and will need side shoots removed to maintain a single fruiting vine. If the side shoots are allowed to remain the plant will put energy into producing more vines at the expense of fruit production.

The side shoots (I’m pointing to it above) grow from the junction between the main stem and a leaf branch. They are easily removed when small by pinching off but if they have got as thick as the one above they are better removed with a sharp knife or secateurs to avoid tearing the stem.

Planting cucumber seedling

Planting Cucumbers
By rights I should have waited a week or two more to plant my cucumbers into the beds but I was impatient to get the job done so went for it anyway. I will probably regret this; as Klaus Laitenberger says in his book ‘Vegetables for the polytunnel and greenhouse’, “cucumbers can grow very quickly but they can also die quickly if conditions are wrong”.

Cucumbers are tropical plants that need plenty of heat and moisture and are best planted in the polytunnel from mid May when the soil is warm and cold nights are unlikely. I will protect mine with fleece on colder nights but I am not guaranteed they will survive. If not, it’s not the end of the world as you can re-sow up to late May is I can try again.

Cucumber plant twine support

Cucumbers are prone to stem rot so, unlike tomatoes, should not be planted deep. The compost level from the pot should be the same, if not slightly proud, as the surrounding soil level to ensure no soil is lying against the stem. Plants will appreciate warm soil with plenty of water going to the roots but shouldn’t be sitting in damp soil. It’s a tricky balance and can be solved by burying a watering tube in the soil but that, as they say, is another story.

Cucumber video

Cucumber Video
If you would like to learn more about cucumbers including growing, male/female flowers and see the process from seed to harvest you can tune in to one of our videos where I take you through the process, I hope you find it helpful.

2 comments
  1. Richard

    Hello Andrew, I really enjoyed reading your article about planting tomatoes, chillis, and cucumbers in the polytunnel, I found it very helpful. Thank you, Richard

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