Each season I sow tomato seeds early in order to take photos for the newsletter and website – that’s my excuse anyway!
I find that seeds taken from my own tomatoes the season before, are always more vigorous than bought seeds. Saving seeds from your own tomatoes also means that you know exactly what you are going to get when they fruit.
Supermarket Tomatoes and Seeds
It is possible to save the seeds of supermarket tomatoes. The value ones aren’t worth growing – they just have a long shelf life and no taste. Those on the vine are the ones to save, especially the smaller varieties like Piccolo and Sunstream.
Also check out the country of origin, if it is Spain or Israel, the variety probably needs the same temperatures that would be found there, so go for a British grown tom.
Piccolo and Sunstream are professional varieties that need consistent growing conditions to do well – best grown in a greenhouse or tunnel.
At around 20c in an electric propagator with a thermostat, it takes five or six days for germination.
In the airing cupboard, where temperatures are warm during the day and cooler at night, it takes six or seven days. For the sake of one day, it’s less expensive in the airing cupboard!
By germinating seeds at the same temperatures means that you’ll know how long they’ll take to germinate.
Some varieties take longer to germinate than others – a good reason to keep varieties in separate seed trays.
On another visit to Poundland (I can’t seem to stay out of that shop) I found the planting mat that Rhys mentioned in the comments of last week’s newsletter. It makes a small but effective portable potting mat – just right for filling a seed tray or a few small pots without making a mess.
Check out the other many useful items for a pound!
Their large pots are good value too.
Hormones coordinate growth. They send a message from one part of a plant to another, to tell cells to do something.
For example, a seedling leans towards the light.
This happens because the hormone auxin is sent from the tip, down the shade side of the stem which elongates the cells on that side.
Because the cells are elongated on the shade side of the stem, and not the light side of the stem, the seedling leans or bends towards the light.
Auxin is also used to promote rooting activity so it’s the stuff gardeners use when taking cuttings by dipping the stem in the rooting powder or gel. I contacted the makers of Rootit rooting gel to ask about the hormone levels in their gel. They said that their rooting gel contains less hormone than is in the plant already – that’s good!
Auxin also helps when grafting too!
How to tell which nutrient a plant needs when leaves show the same symptoms!
Nutrient Mobility and Translocation
Some nutrients are considered mobile and some immobile.
Nitrogen, for example, moves around a plant’s system quickly – because nitrogen is mobile. Calcium on the other hand, is immobile and does not move from one part of a plant to another, once it gets into a plants system it stays in that area.
If top leaves need more nitrogen than is being supplied by the roots, the top leaves will take the extra nitrogen they need from the lower leaves.
So if the lower leaves are turning pale and look as if they are in need of a good feed (plant A), it is probably because the top growth has taken their nitrogen!
Magnesium is also mobile and is regularly moved from the lower to the upper leaves if required.
However, when top leaves are pale and lower leaves are ok (plant B), it cannot be a nitrogen or magnesium shortage. If it were, the top leaves would have removed them from the lower leaves.
So, when top leaves are pale (plant B), it is most likely an immobile nutrient that is deficient.
Calcium is immobile and that is why we have so much Blossom End Rot in fruit. A slight shortage of Calcium when the tomatoes are forming will cause BER.
Calcium deficiency also shows as stunted new growth at the growing tip.
To a lesser extent iron (semi-mobile) will also show as a deficiency in the top leaves. Pale yellow/green leaves around the growing tip is likely to be an iron shortage.
Every time nutrient intake (and moisture) through the roots slows or stops, means that the flow of immobile nutrients such as calcium and iron are interrupted and a deficiency is likely to occur.
This is one very good reason why having nutrients available 24/7, by way of water reservoirs etc., is the better way to grow tomatoes.
Temperatures, nutrient balance in the soil and pH also play their role. However, if a plant starts off healthy then shows leaf symptoms as described above, it can be quickly diagnosed and a foliar spray applied.
That’s it for this week – I know that some of you have already started sowing, so if you have, I hope your seedlings are doing well!
PS Comments welcome as always below.
It’s always a good idea to sow varieties that are popular such as Gardener’s Delight and Moneymaker. They are popular for a good reason, that is, they are reliable and most likely to succeed.
If you are new, or not so new to growing tomatoes, growing the larger varieties takes more experience and requires a good summer!
Timing is also an issue. Sow too soon and plants struggle through poor conditions. Sow too late and tomatoes won’t be ripe before the weather turns colder in the autumn. March to April is ideal.