When, how and why is it important to "Stop off "tomato plants

Tomato plant growing in a pavement crack
Tomato plant growing in a pavement crack

Why Stop off Tomatoes

Tomatoes are really vigorous and this is part of the reason we have to stop them growing at some point.

The image left shows just how vigorous tomatoes are. This is a tomato plant, growing in a city centre, in the scant soil provided in a pavement crack. The original seed probably came from a sandwich. This plant will produce lots of leaves, grow well, but sadly few tomatoes.

If we leave tomato plants unchecked, not only will they make lots of side shoots, they will also grow up and up. The plant will produce masses of growth and leaf at the expense of the flowers and fruit, so to get a good crop, it is necessary to constrain the plant. 


When is the time to stop off tomatoes?

In around August / September, (depending on where you garden in the country and the growing season,) it is necessary to "stop off" the tomato plants.  This means pinching out the growing tips at the top of the plant and stop the plant growing up any further. Stop off at the top of the plant when there are 3-4 (outside grown) and 4-5 (greenhouse grown) trusses, which are layers of flowers. The exact timing of when to stop the plant growing depends on when it has set enough trusses, which depends on growing conditions.

Continue taking out the growing points as the plant will strive to keep growing. This means once you have cut off the top of the plant to stop it growing, you will need to do this again, and again, as it will keep trying to grow through the greenhouse ceiling.  

Growth point cut off tomato
Growth point cut off tomato

How to stop off tomatoes

In this image, the plant is actually resting on the top of the greenhouse roof. Above the flower is the pane of glass forming the top of the roof so the tomato plant has reached the roof and developed the maximum number of trusses.

The arrow shows the growth point just after it was cut off. Within a couple of weeks shoots will appear alongside the cut off point as the tomato attempts to re grow, cut these off as well.

Tug full of tomato leaves
tug full of tomato leaves

Thin out the leaves

Later in the season, thin out the tomato foliage which will divert the plant's energy into making fruits and not more and more leaves. Towards the end of the season, the plant shouldn't have masses of leaves on it. Be bold, cut them off. At the peak of the growing season, I remove lots of leaves each week when checking the tomatoes. The image shows a trug full and I may cut this amount off, towards the end of the growing season, every week to 10 days. This also aids ventilation, which helps to reduce the risk of diseases. 

You may spot a few flowers in the cut-offs. Toward the end of the season, you will have to decide which flowers will come to maturity, and which to sacrifice, in order to get the other flowers and fruits to mature. I often leave any with immature fruits forming and cut off those which are newly formed flowers. It depends on your growing conditions when to consider this. When you feel the season is slowing down, and light levels are starting incrementally to fall, there is only limited time left for the fruits to swell and its better to concentrate a few less fruit as not all will mature. 

Step-by-step guide to growing tomatoes

Follow the Sunday gardener's step-by-step advice about growing tomatoes to ensure you have a successful sweet tasty crop every harvest. 

  1.  How to grow tomatoes
  2. How to grow tomatoes from seed and what to do about weedy seedlings
  3. What are the easiest tomatoes to grow? Cordon or Bush?
  4. How to pot on tomatoes, dos and don'ts,  and why it is important.
  5. Hardening off tomatoes for growing outside
  6. Pinching out Side Shoots on tomatoes
  7. The Best way to Water and Feed Tomatoes
  8. How to ripen Green Tomatoes
  9. Common pest and diseases when growing tomatoes
  10. If you have found these tips helpful, why not buy the book: Success with Tomatoes The Sunday Gardener's guide to growing tomatoes, packed full of practical tips and helpful images, everything you need to know to grow a tasty crop. Only £6.20
Tomatoes in greenhouse with ripening fruit

last updated 13.09.2022