It’s difficult to move in my polytunnel … too many tomato plants and too many experiments going on, but it’s been a very exciting season so far!
The good weather has helped a lot. Even the plants that were spindly/leggy have suddenly decided to thicken-up and look like they want to show what they can do.
pH, friendly microbes and air
One of the advantages of growing in soil (including multi-purpose compost and grow bag soil etc.), is that it takes care of a number of things for us, that is, it provides a suitable pH and a healthy environment for friendly microbes that roots need to function properly.
Soil contains elements or buffers that keep pH within an acceptable range for our plants, and if the soil is well aerated, friendly microbes will grow and promote root health and nutrient absorption.
It’s a fact that oxygen in the soil and well oxygenated water added to the roots helps nutrient absorption.
We play our part of providing air, water and nutrients and the soil/compost does the rest to feed the plants and provide the healthy environment that the roots need.
Badly oxygenated water
Rain water from the water butt that smells horrible is probably full of bacteria that are likely to damage plant roots. Furthermore, if the water is taken from a roof where pigeons sit and mess on the tiles below, you probably have a water butt full of raw bird poo – stuff that your plants don’t want!
When to remove the growing tip
Tomato plants have two stages of growth – the vegetative (growth) and the reproductive stage (fruiting).
Professional growers are aware of the fact that they need to encourage plants from one stage to the other and to keep a balance that will produce a good crop of tomatoes over a set period of time. This is done by nutrition and pruning to name but two methods.
The growing tip is the most “favoured” part of the tomato plant. It is able to take (mobile) nutrients from lower leaves if there is a shortage of nitrogen or magnesium for example. You will see this happen when the lower leaves turn pale green or yellow and upper leaves look perfectly healthy.
If we remove the growing tip before the first truss has set, that is, started to grow small tomatoes, we will be sending the nitrogen meant for cell growth of the growing tip, around the plant. This will keep the plant in the vegetative stage longer, producing leaves rather than fruit.
However, after the first truss has set, a small burst of nitrogen is beneficial. It won’t produce heavy leaf growth because the plant has already entered the fruiting stage or reproductive stage but will encourage further truss development higher on the plant. This is particularly useful when growing large varieties that tend to run out of steam when they reach the third truss.
To sum up
It’s best not to remove the growing tip at least until after the first truss has set. You may have several trusses set before the growing tip needs to be removed, but the plant should be in the fruiting stage.
I generally allow six or seven trusses on a tall cherry variety. Five or six on a medium variety and four or five trusses on a beefsteak variety.
Too much sun!
One of the disadvantages with lots of direct sunlight is blotchy ripening, sunscald and greenback.
Blotchy ripening happens when tomatoes in direct sunlight are unable to produce lycopene because of the heat. Lycopene is the red pigment in the skin and flesh of the fruit.
Sunscald is when the skin is damaged and a pale brown papery patch appears.
Another condition is greenback which can also be caused by too much direct sunlight. The shoulders of the fruit fail to ripen – some varieties are more susceptible than others.
Blotchy ripening and greenback can also be cause by a lack of potassium (potash).
Always happy to answer questions!