Growing outdoors tomatoes succesfully in the north

I’d like to share what I’ve learned about tomatoes growing in my region (Lorraine, France), so that everyone can enjoy it, it seems important to me because I’ve never found a condensed summary, like I’m about to share, in any book or on any internet page.

Firstly, for those who know me, I always look for the best way to do things while working as little as possible (in the long term) and allow plants to grow naturally as they wish. So I won’t in no way talk about cutting suckers, watering or using any treatment on the plants. I’m simply trying to offer the best environment to the plants, so that they are happy; plants in good health will be plants that bring good results for us as well, it’s as simple as that.

Also one other important information, setting up what I’m describing might take some time, but in the long term it will be much better for us and for the tomato plants; it’s really worth it.

The first and most evident thing is, to have a south exposure as much as possible, to benefit the most from the little amounts of sun we can have in northern regions!
tomatoes sun

On this schematic, the circle indicates the suns’ position rising in the east and setting in the west. The south exposition must be as good as possible because we’re going to wall off the northern side, we’ll basically plant tomatoes in front of a wall or a big pile of stones. The point is to just have as many stones as possible on the northern side, because these stones will first of all protect the tomatoes from strong winds that most often come from the north or north-west and they will act as a slow diffusion heater, exposed to the sun most of the time, the wall or stones will collect heat and release it slowly when sun is lacking and during the night.

Don’t hesitate to make it tall, a 2 m tall wall is a good size! There is no sun coming from the northern side, so we might as well have as many stones as possible to collect heat. It is also useful to add stones all around the tomatoes, they will all collect/release heat and under the stones, humidity will be retained for longer periods.

The second, and very important point; tomatoes love water but they don’t like being wet! That’s generally the biggest problem in northern regions, excess rain causing blight, which I personally think of as the cold of tomatoes. From my own observations I discovered that the problem is not rain itself, it’s that in the north, when it rains it usually means that a low-pressure system is arriving and temperatures are going to drop, which in turn will prevent the tomato plant leaves from drying up quickly. Whereas in southern regions, when it rains, the temperatures remain the same and the water on the leaves will evaporate almost as quickly as it fell. And that’s the most important aspect to understand, it’s as if a human in the north stayed outside by 30°C under heavy rain and then staying the rest of the day wet because the temperatures dropped to 20°C afterwards, a perfect way to catch a cold. Whereas in southern regions you are otuside, get soaked by a heavy rain, but the temperatures remain as high and one hour later you’re dry again as if nothing happened!

Thus, it is an absolute necessity in northern regions to have a roof on top of your tomato plants! That way, the leaves won’t ever become too wet, with the wall on the northern side you can simply attach the roof at a height of about 2 m. But since we have a lot of rain in the north, we might as well use it well, tomatoes love water, there are two ways to do it easily. If like me you have a chance to put your tomatoes in a place with a heavy clay soil where water is always plentiful 10-20 cm below, you don’t have to do much, just be sure that the bottom of the plant is not soaked in water (by planting it high enough), but making sure that the roots can go deeper by themselves to collect the water they need. If you have a sandy soil, or a soil that dries up quickly, then the best is to put a gutter on the roof to direct rain water straight into the soil aroudn the tomatoes feet.

I said it earlier, in no way are we going to remove the suckers, a name very badly chosen if you want my opinion, because these suckers will grow into branches that will give more tomatoes if the plant is robust, many more tomatoes! The additional leaves will not prevent tomatoes from growing well, on the contrary, these leaves will collect more sunlight to be able to grow more tomatoes at the same time. A tomato plant that grows well and healthy without ever being trimmed can easily produce 10 times more tomatoes than one on which all suckers are removed. Here we have to set up cages, a prop is useless, we have to support the tomato plant from the outside with a grid around it on which all branches will be able to lie instead of attaching the central stem. The easiest method is a round grid cage made with grid of about 2 m length (about 20 x 20 cm mesh), which is rolled on itself, making a grid tube of about 60 cm diameter. A tomato plant growing freely becomes a big bush!

tomato cage

Example, with a wall facing south:

Exemple tomates

The roof is drawn in brown, the gutter in red, with a drop by drop irrigation system (still with a good flow) to direct rainwater directly around the tomatoes cages when it rains. That’s about it, just put one tomato plant in the middle of each cage and you’re set. In these conditions, tomatoes will have enough heat, they will be protected from the rain and will be naturally watered at their base without making their leaves excessively wet when it rains. You can also (I recommend it) add a big layer of mulch/straw etc. around the tomatoes to keep the soil humid for longer periods when it is dry.

With these cages you can also easily use a method of electroculture by adding a copper pipe as central prop, using the method described in schematic B on this page: Electroculture – Basics

But don’t forget that you shouldn’t connect the grid from the bottom with the grid on top in this case, you just need this grid of galvanised iron mesh around the base, wit ha grid of around 30-40 cm height halfway buried into the ground. Here’s a schematic below to show what I think is the best to do for the cage.

cage schematic

The support poles don’t need to be made of wood, but they must be in a material that is an electrical insulator, hence no metal: wood or plastic is the most practical.

Then, grid 1 is the one used for the electroculture method, I didn’t draw the central copper antenna, but it obviously needs to be there. The grid 1 is in galvanized iron. Then grid 2 is placed a bit higher, not connected to the bottom one and it has a larger mesh (~ 20 x 20 cm), because this is where the tomato branches will have to go past the grid when they grow and use it as support. Then I still recommend to not connect grid 2 to grid 1, and grid 3 to grid 2 etc. for higher up grids. Because there is a small voltage potential difference between the ground and any metallic thing that is higher up in the air not electrically grounded. The higher the grid is, the larger of a voltage difference there is. I’m talking here about differences that can be measured in 0,1 V etc. But for a plant these are huge differences of potentials!

This cage system is useful in any region, not just for northern ones…

The following page is sadly only in french, tomate en cage it provides informations about misconceptions people have about growing tomatoes which are completely wrong!

Here’s a small summary of the most important points:

  • Letting suckers grow does not mean that tomatoes will be smaller, if the plant is growing freely there will be many more tomatoes on one plant and all of the same size, if you had cut all the suckers you’d get the same size tomatoes but in a much smaller quantity.
  • Tomatoes don’t need to be exposed to the sun to grow, on the contrary it burns them! Leaves need to be exposed to the sun to collect the energy to grow the tomatoes that are protected by the leaves from excessive sunlight.
  • Letting suckers grow won’t delay the growth of the first tomatoes, they will grow at the same speed and additional ones will grow on the new branches, once the suckers have developed into full grown branches.

I forgot to specify that this method of growing tomatoes in cages is much more useful for indeterminate varieties (that grow indefinitely) than determinate ones (that stay quite short), on the other hand, the wall and the roof, that’s good for any variety of tomatoes in any northern region!

That’s it folks, it will take a bit of time to set up such an installation, but it’s really worth it in the long term to have nice and healthy tomato plants, that do not require much care and provide us with plenty of tomatoes!