The question posed in last week’s newsletter was, “why do tomatoes that are grown outdoors split when it rains?” and it has produced some good comments.
To those who have been contacted, you will receive Red Alert (bush) and Stupice (tall) seeds and they should arrive this coming week.
The traditional answer of dry soil followed by too much water is generally correct, especially for greenhouse grown tomatoes. Roy gave us a list (in the comments of last week’s newsletter), of good reasons why tomatoes split. Both Roy and Nic also touched on temperature, this is another variable to be taken into account.
Here’s my answer to “why do tomatoes that are grown outdoors split when it rains?”.
Tomato Plants are similar to humans in some ways …
- We have veins, blood and blood pressure.
- Tomato plants have veins, water and water pressure.
Tomato leaves are very absorbent and when it rains, plants take on moisture through their leaves and roots, creating maximum pressure within their system. Therefore, ripe tomatoes become fully pressurized like a balloon filled to the maximum.
However, rain falling on the tomato skins lowers the skin temperature slightly, causing the skins to contract – the skins then split.
Even if outdoor plants are watered regularly so that their soil remains moist, a downpour of rain can increase the pressure inside ripe tomatoes and shrink the outside skins at the same time!
Fortunately, as soon as the first few toms split, the pressure inside a plant’s system drops slightly and the rest of the tomatoes are out of danger!
In my experience, varieties that contain a lot of juice such as Sungold and Black Cherry split more easily than those that contain less moisture – Roma is a good example and great on the barbecue because of its fleshy qualities rather than juicy qualities.
Black Cherry is a lovely juicy variety and great for saving seeds!
Putting warm tomatoes in the fridge can also cause the same affect – the skins shrink faster than the inside because of the sudden cold air and so they sometimes split, as suggested by Avril.
Keeping Leaves Dry
The problem of splitting skins brings us back to one of the biggest “do’s” in tomato growing – keep the rain off leaves and fruit if possible.
I have plants outside exposed to rain, plants outside but sheltered from rain and plants in a greenhouse. This gives me the benefit of experiencing the results of different growing conditions on the varieties I grow.
Choose a Mix of Varieties
As suggested in a previous newsletter, this gives the advantage of being able to contrast and compare and often reach a conclusion and find an answer to a problem when things go wrong – as they will every season!
When considering which varieties to grow next season, try choosing tall and bush varieties, and also ones that are early to mature. Also, devising a way to shelter your outdoor plants from rain will increase the chance of success and lessen the chance for disease – aka – Tomato Blight!
Bush varieties have many advantages but one supposed disadvantage is that all the tomatoes fruit within a short period.
I say “supposed” because I have two Red Alert plants that started producing ripe fruit back in the middle of June and they are still producing ripe fruit at the end of September.
Also, of all the varieties I’ve ever grown, the cherry/bush varieties are among the best tasting and I would recommend Red Alert and Maskotka along with Tumbling Tom to everyone for next season.
There is one yellow Tumbling Tom plant in the greenhouse (above) that has produced well over two hundred tomatoes so far this season! They may not be big in size, but if I were to weigh them all, I’m sure that this one plant could compete with many of the larger varieties in the weight produced.
One disadvantage with bush varieties is that their branches tend to break away from the main central stem because of the weight of tomatoes.
Usually, the plant can still function and water/nutrients will still pass through to the leaves and fruit. This plant has been in this condition for about two months but is still producing well.
Next week is the last newsletter of the season!
Please leave a comment below if you would like to.