Many problems aren’t life threatening to a plant although they may result in a reduced crop – tomato leaf roll is one of them.
They say that a tomato grower with poor eyesight sleeps better at night! It’s easy to find worrying looking marks on just about any tomato plant if you look closely enough.
Tomato Leaf Roll
One of the biggest issues at the moment is leaf roll.
Some varieties roll some of their lower leaves by default, but in high temperatures, leaf roll, leaf cupping and leaf curl are highly likely to occur on most plants – especially those grown in containers and grow bags with limited resources.
By reducing water and heat stress, leaf roll and a number of other issues can be kept under control.
Watering – water stress
The challenge here is to provide water 24/7. The problem is that plants absorb different amounts of water each day, depending on the growing conditions … temperatures, light levels, humidity and air flow all effect the amount of water a plant needs.
The only way we can ensure that water is available whenever a plant needs it, without over watering, is by using an auto watering valve or a reservoir system.
Heat – heat stress
When light and temperature levels are high, plants will do everything they can to protect themselves from running out of moisture and wilting.
This includes diverting moisture from swelling fruit to leaves, which may result in Blossom End Rot.
Not only do plants curl their leaves in a number of ways, but they sometimes turn their leaves away from the sun and face them in another direction!
It may seem that when growing tomatoes, we are always battling something – especially the weather!
Too cold, too hot and not enough light to name just a few of the regular challenges we face from season to season.
However, no two seasons are the same and that includes variations in the taste and sweetness of each variety.
The amount of light the leaves receive and absorb has an effect on the taste.
The darker the leaves, the more light they absorb and a good reason to apply magnesium by foliar spraying when light levels are low during long periods of dull weather (magnesium darkens the leaf colour).
If the lower half of a plant’s leaves are tightly curled, it will have an effect on the taste of the tomatoes on the lower trusses because sugar production in the leaves will be reduced.
High temperatures can also reduce the sweetness of the fruit when respiration (which uses leaf sugars) overtakes photosynthesis (makes leaf sugars) and the plant uses more energy than it makes.
Over watering too can reduce the amount of nutrients plants receive which can also effect the taste.
You will also find that the acid content of tomatoes is a little higher in the earlier part of the season.
Over the past few seasons I’ve been using organic feeds on some of my plants. One make that I’ve found produces good results is “Miracle Gro” Grow Your Own Fruit and Vegetable Concentrated Plant Food – Organic Choice .
It’s a lovely thick dark mixture of chemical free organic nutrients (NPK 3-2-6). Give the container a good shake each time you use it to avoid lumps forming in the bottom. Using in conjunction with liquid seaweed makes a great organic duo of feed and booster.
The way to feed
There are many options for feeding organically but whatever you use, it’s important to feed little and often to encourage and retain good soil microbe activity. Also, the more air/oxygen that can be added to a liquid feed by shaking the better. Pouring one watering can into another (or similar) will add oxygen that will encourage soil activity, root health and rapid growth.
That’s about it for this week – if your plants are struggling with the heat, don’t forget to use shade cloth such as garden fleece, remove unnecessary leaf branches (see pruning) and cover black pots in direct sunlight with white card, paper or plastic to keep the temperature of the roots down.
It’s all go – but it’s good to have a sunny season!