Each season I promise myself not to sow too early and not to sow too many seeds and tomato varieties – both promises broken already!
The thing is, by the time I’d sown a few Gardener’s Delight, Alicante, Black Cherry and Sungold, there were still a lot of varieties left to sow … not to mention the cuttings!
It would seem impolite not to grow an heirloom or two such as Beam’s Yellow Pear or Hill Billy Potato Leaf.
The shape of the yellow pears and colours of the HBPL toms are magnificent!
How could I not grow Roma … a great tomato for cooking and an excellent excuse for a fry-up or grill.
Having taken about 20 cuttings from the Red Alert and Maskotka plants that were grown over the winter, some of which are now in flower, my porch looks like a jungle – the trouble is … it’s now snowing outside!
Playing safe and sowing plenty of cherry bush varieties for reliability in a poor summer – you can never have too many cherry tomatoes!
Then there are the seeds that have been given to me by kind folk who would like to share their unusual varieties – how could I not sow those!
All in all, my house and polytunnel look like a garden centre and it’s not even April!
Just like busses – they all come at once
One of the disadvantages of growing bush varieties, is that the tomatoes all ripen at the same time, or within a short period, and the plants are then finished.
Sowing over a period and having plants fruit at different times is one way to overcome a glut of tomatoes.
There is another way for bush varieties
It’s possible to prevent bush varieties from going into “full fruiting mode” by restricting the amount of feed, especially potassium (potash), given when they begin to fruit. In other words, continuing to feed a general feed into the fruiting period rather than a tomato feed.
As I’ve mentioned before, over the winter I grew a couple of bush varieties that have been fruiting (gradually) for over two months and are still producing more side shoots and flowers – and more fruit.
The plants have been fed a general feed at medium/low dose and will continue in this mode of growing side shoots, flowering and fruiting until I give them their final “last phase feed” …. tomato food!
There are lessons to be learned here for tall varieties too.
If you over-do the tomato food when the first truss starts to set, it is likely that fruit on higher trusses will be less productive. Why? because the tomato food (heavy on the potash) will send plants into full fruiting mode which slows down new vegetative growth.
This means that growth above the first truss is reduced unless adequate nitrogen is given.
There is a way to achieve a balance in order to get a good crop from higher trusses.
This is done by adding extra nitrogen (for a limited time) after the first truss has set in order to continue the upward growth.
Another method is to continue giving a balanced feed until the second truss starts to set.
More about this in a future newsletter.
Tomato Taste – a second chance
We all know that each variety has its own specific taste. Some are very sweet such as Sungold, some are a good balance of sugar/acid such as Gardener’s Delight or Red Alert and some have a mild flavour such as the yellow Golden Sunrise.
However, the same variety can taste different from season to season depending on the summer light levels (and amount of sugars made during photosynthesis).
On the same truss
In a poor summer, when photosynthesis sugar production is low, the tomatoes growing on a truss nearest the main stem will receive more sugars and will taste slightly sweeter than those further down the truss. In other words, first come first served!
The nutrient balance also has an effect on taste – too much nitrogen for an extended period can make tomatoes taste watery.
Knowing which nutrients plants need at the different stages of growth is a major part of the art of growing tomatoes for taste, yield and longevity of the plant.
So when your tom tastes disappointing, it is either a poor summer and low sugar content (last year was poor!) or the way they’ve been fed and watered.
Soil, rain and tap water pH
In order for plants to absorb the nutrients they need, pH has to be right.
Potting compost, including the John Innes mix and multi-purpose compost, usually falls within an acceptable range for growing tomatoes (see lest week’s newsletter).
If you are using peat-free compost, I would definitely test the pH because, in my experience, it is very inconsistent.
If peat-free hasn’t been composted properly, you are buying a bag of trouble, so it’s best to buy the best like New Horizon and avoid the cheap stuff!
Tomato plants like it on the acidic side
Peat provides the acid side of the acid/alkaline balance. Tomato plants like soil that is slightly on the acid side, so if there is no peat, it’s important that the right mix of materials have been composted or a substitute such as sulphur added by the manufacturer.
Rainwater and tap water
Pure water is pH 7.0 (that’s neutral – in the middle of the acid/alkaline balance). However, as rain water falls, it absorbs gasses and pollution from the atmosphere which makes it slightly acidic.
This is great for tomato plants growing outside as they get watered with a pH they like. Of course you can always collect rain water in a water butt too. Tomato plants growing outside often receive a mix of low pH rain water and high pH tap water – that’s OK if it’s mixed together.
It is sometimes suggested that the pH of tap or rain water has little effect on the nutrient uptake of tomato plants – especially those grown in soil and containers, however, in my experience it has a big effect.
The season I changed from growing most of my plants outside (in the rain) to growing most of my plants under cover and watering mainly with tap water, I had a very disappointing harvest and plants suffered from nutrient deficiencies.
Very frustrating after spending quite a bit on a pollytunnel!
The reason was, plants outside were watered regularly with rain water with a pH of around 6.0 (a suitable pH), the plants under cover were watered only with water from my tap, that was too alkaline – around pH 8.0. My plants were unable to absorb all the nutrients they needed and a poor harvest was the result.
It’s extremely easy to adjust the pH of water … add lemon juice to lower the pH (makes it more acidic) or baking soda to raise the pH (makes it more alkaline).
When nutrients are added to water, the pH is usually lowered slightly too.
These days I know the pH of my tap and rain water and I often test the pH of the water in the watering can after I add nutrients.
The test kit I use, is here (please scroll to bottom of page) – it’s cheap and simple. I aim for a pH of around 6.5 for a soil/perlite mix.
That’s it for this week, please leave any comments below.