Growing Tomatoes Without a Greenhouse in SE England (Part 1)

5 Nov

My name is Rhys Jaggar, and I live in north west London, UK. I was invited to become a guest blogger by Annette and Lucia, co-authors of the book How to Grow Juicy Tasty Tomatoes. This blogpost is part 1 of my story about growing tomatoes without a greenhouse, and I hope it inspires other growers to experiment too!

Q: How long have you been growing tomatoes?

Award winning tomatoes

I started growing tomatoes about 5 years ago and, after a few years of following ‘tried and tested methods’, started experimenting for myself, trying to test and adapt various strategies to the location I grow my tomatoes at. Two or three years ago I bought Annette and Lucia’s book ‘How to Grow Juicy Tasty Tomatoes’ and it gave me the confidence and framework to become an experimental tomato grower. The past two years I have won first prizes in the village and borough shows, as well as third prize at the London autumn show.

Q: What general method do you use to grow tomatoes?

I grow all my tomatoes in pots on a patio using compost usually purchased from a local horticultural society. Living on the NW edge of one of the world’s most expensive cities, I don’t have 2 hectares of farmland!

I’ve grown a few in the garden soil successfully, but our garden isn’t big enough (see pictures below) to grow 24 plants there without sacrificing all the crops which can only be grown there, so this is a pragmatic choice rather than a dictum that you shouldn’t grow tomatoes in your vegetable patch!

Q: Where are you based?

I am based about 15 minutes by car north of Heathrow airport, at the edge of NW London suburbia. In general, that gives us a 3 month window between mid-June and mid-September when the climate is reliably warm enough for tomatoes to live outside 24hrs a day, with daytime warm enough for 6 – 12 weeks in addition to that, depending on year.

Q: How many plants do you grow and how many tomatoes did you harvest?

This season I managed to harvest 118lb from 24 tomato plants, from the first week in June to the 3^rd week in October. These were small cherries, golf-ball-sized cherries, traditional salad tomatoes and 3 strains of beefsteak tomatoes.

Q: Was 2014 a typical tomato-growing year?

A year such as 2014 was very different to the average and my earliest plants were enjoying outdoor sunshine even in early April during daylight hours (see picture below) and still yielding ripening fruit up to 20^th October (most unusual). The garage is an overnight home for plants if unseasonal cold comes along, which wasn’t the case in 2014 but has been in other years, notably 2013, where May and June were particularly cold prior to a long hot, dry summer throughout July and August.

Tomato plants enjoying sunshine in early April

Q: Can you grow tomatoes without a greenhouse in SE England?

You don’t need a greenhouse to grow tomatoes in the SE of the UK, however you probably do need protection from the rain, since temperatures here are not reliably hot enough to prevent wet plants developing disease. My plants live under a carport structure when it is wet.

Q: What other life experiences have helped you to grow tomatoes well?

I started life as a research biologist, which in a strange way, is a good preparation for growing vegetables:

Experiments took a long time to yield results, so planning was imperative;
Lots of unknown variables exist, which makes trouble shooting for the inexperienced both time consuming and frustrating; and thirdly
Many of the ‘bibles’ of ‘protocols’ appeared to have been written by experts for those who had already been at the research bench for 5 years. Little things which experts knew as ‘obvious’ were left out, which left novices to make the mistakes that their omissions did not warn against.

So I came to tomato growing with a mind-set that you had to find the right way to grow tomatoes in your situation, although what experts said would no doubt apply in many situations for many people, so long as you understood the context underlying the advice given.

Q: As the British climate varies so much from year to year, how can you plan for growing tomatoes successfully outdoors?

Whilst annual climate variations are indeed beyond our control, there are some things, which ARE reliable from year to year. The most notable of those is the length of day. The longest days in London are between the beginning of May and the end of July (seven weeks either side of the solstice) and your tomato crop will be influenced to no small degree by how many sunlight hours your plants can enjoy during that 3-month period.

That is the period for optimising your photosynthetic factory of leaves and your tomato trusses, to generate the flowers, which turn into fruit and to get your fruit swelling nicely.

By the end of July, you will know the general fate of your season although, like vine growers, it is still in your power to destroy what you have created through bad luck, fate or incompetence. You can’t rescue a bad season by this time, however.

My first set of plans therefore involve ensuring that my young plants are ready to benefit from that 3 month window of long days by being sufficiently advanced in their growth so to do.

The second reliable feature of tomato growing is the stages the plant must go through from seed to harvest. It’s quite easy to break these down as follows:

Germination and early growth – creating a new seedling with two cotyledons, which progresses to a young seedling with true leaves;

Vegetative growth – a phase of very rapid growth where the plant increases in relative size extremely rapidly before creating its first truss:

You can see that in 6 weeks, the plant has increased in height and wingspan by 600 – 800% and the first truss has formed at the end of week 7.

Flowering and fruit set – the plant keeps growing but trusses form regularly, which flower and set young fruit:

Fruit growth – the set fruit swell reliably to a mature size;
Fruit ripening and harvest – the mature fruit change from green to final colour (usually but not always red):

Q: How did you go about understanding those phases better?

In 2014, I decided to keep detailed records of each of these phases, not because it hasn’t been done before but simply because I wanted to know how my plants behaved where I grew them so I could plan reliably for future seasons, as well as experiment with new approaches to see if improvements could be made.

Q: Why did you decide to do this?

I only did this once I knew that I could grow tomatoes reasonably reliably, as then I would be experimenting from a reliable baseline to which I could return if experiments didn’t succeed (from 30 years of experimentation in a variety of parts of life, I can reliably inform you that if you aren’t failing sometimes, you aren’t experimenting!)

Q: What sorts of things did you measure?

Here are some things I measured:

Time to germination and percentage of seeds which germinated successfully;
Number of true leaves, side stems and main stems from seedling up to 10 weeks post sowing;
Height and wingspan of plants on a weekly basis up to 10 weeks;
Number of trusses, numbers of flowers, numbers of blossom drops and numbers of visible fruit (the latter two aren’t always the same if fruit set is less than optimal);
Number of fruit ripening and numbers and weight of fruit harvested.

Q: All that sounds terribly complicated: how long did it take you to do that?

I did this on a weekly basis – for 24 plants through a season it takes no more than 1 hour a week to do the measurements and record them on Excel spreadsheets.

Q: did you need any fancy equipment to do that?

All you need is a ruler (young plants) or tape measure (older plants) (a gardener’s 5m measure works well) and a pen and paper (since sunshine usually stops you seeing your computer screen clearly if you try recording data directly). You will learn a lot about tomato growing by doing this yourselves, where you live, with the strains you grow, in the way you grow them, with the constraints that you have at your site.

Q: Do you feel more confident about growing tomatoes now you’ve done that?

Yes, doing that measurement has given me a holistic overview of the annual cycle of the tomato plant from seed until I kill it in the autumn. It also makes me feel more relaxed or become justifiably worried, since I now have a template for a timetable for healthy tomato plant growth and maturation!

Q: Can you give us some specific examples of what you learned by doing that?

Firstly, I have a reasonably good initial understanding of what varies between different tomato strains and what doesn’t.

Here are a few examples:

There is very little difference across many salad- and beefsteak tomato strains in terms of how long it takes from sowing a seed to creating the first truss and harvesting the first ripe fruit, if you sow them all at the same time;
Those timings are shortened as you sow from February through to April;
There are some strains which are noticeably quicker in terms of time to harvest, including:
- Maskotka (golf-ball-sized cherries on a bush);
- Red Alert (which only germinated for me in late May this year but produced fruit by late August);
- Glacier (a salad tomato known to grow in very northern latitudes); and
- a new strain I grew this year, Zenith (which produced beautiful salad tomatoes from early August after an early April sowing);
There are also a few strains which benefit from longer seasons to come to maturity more effectively – two I have found to be like this are Black Cherry (which benefitted from moving sowing date from mid March to early February this year) and Riesentraube (which also benefitted from an early March sowing rather than later and which I will shift even earlier next year);
As it takes salad/beefsteak tomatoes at least 6 – 8 weeks from fruit set to ripening, you should aim to have completed fruit set by the end of July at the latest and preferably by mid July;
With some cherry varieties, you can continue fruit set up to the middle of August and still harvest some ripe fruit.