Terry’s Top Tips, 1. Getting started, choosing tomato seed
Warm, sweet, succulent tomatoes…sun ripened globes of delight with their blend of sugar and acid and that distinct smell. The very thought of them lifts the spirits on a cold winter's day. So, lets make this a reality…by making 2021 the year of our best tomato crop ever...
The difference between a heavy crop of delicious fruit and a mediocre one is by using our personal facilities to grow a crop within the natural laws that govern the plant. We will look at these laws and how they apply as the season progresses.
With so many varieties of tomato available which ones shall we choose? After carefully reading the details of variety, size, colour, flavour, early or main crop, disease resistance, cordon, bush, dwarf or family preferences!
Broadly speaking, cherries along with early varieties, given good growing conditions will produce ripe tomatoes 15 to 17 weeks after sowing. Some of the larger beef steaks will take a month longer and in a poor summer 22 to 24 weeks before the first fruits are ripe.
For many years, I started the season with ‘Stupice’ an old Czech variety which will produce ripe fruit 16 weeks after sowing and grow at lower temperatures than most other varieties. Another very useful variety is ‘Red Alert’. This 18 to 24 inch tall plant can easily be grown in a 10 inch pot or container and can be moved around to make take advantage of any odd spot with good light and warmth early in the year. Later it can be pruned back to produce new growth for a second crop in autumn.
Next time…Sowing and germination
Terry’s Top Tips, 2. Sowing and germination.
Flavour, that's what it's all about! - The second instalment of author and expert tomato grower Terry Marshall’s top tips...
Having chosen your flavoursome varieties, it is time to get sowing. Many of those beguiling varieties that are now available, work out at 30 to 40 Pence and even up to 75 Pence per seed so 100% germination is essential. Anything less makes each plant expensive so let’s look at how to do this.
Although tomatoes will germinate over a range of temperatures, researchers tell us that 20 degrees centigrade is the optimum temperature for the maximum number of seeds to germinate.
A maximum/minimum thermometer is an invaluable aid to tomato growing. With one, local temperatures can be checked, serving to determine just where is the best place to germinate your seeds. The ideal is a thermostatically controlled propagator but for the past forty years I have used the airing cupboard for early crops with the door open 3 inches. I’ve found it maintains a constant 68 Fahrenheit or 20 degrees Centigrade. Dalefoot Seed Compost comes in a 12-litre bag so it is easy to bring a bag into the house and bring it up to temperature a day before sowing.
Fill a clean tray with moist Dalefoot Seed Compost, level and gently compress it. Sow the seed spaced 5 centimetres apart and 1 to 1.5 centimetres deep and cover the seed with fine compost. Water gently with tepid water and allow to drain. Then, place where it is possible to maintain as nearer temperature to 20 degrees centigrade.
Given good conditions, many modern hybrids may germinate in four to five days if an airing cupboard or a dark place has been used. Do make sure to check the seed tray at least twice a day after the first four days. Forget to do this and in 24 hours the seedlings could become very thin white little corkscrews which is undesirable. Once germinated, place the seed tray in as light a position as possible as near to 20 degrees by day and 13 degrees at night as can be maintained. Keep the top of the compost moist with tepid water or a water spray, taking care not to over water.
Next time; propagation, pots, light and temperature.
Terry’s Top Tips, 3. Propagation
From yoghurt tubs to the latest bamboo pots, tomatoes are often propagated in whatever is to hand. This begs the question what is the optimum size of pot to propagate our tomatoes in? Ideally, we are after a plant that is wider than it is tall with well-shaped dark green hairy leaves. If the plant still has cotyledons, side leaves attached to it, it is a sign that up to this stage the plant has not suffered any form of growth check.
For gardeners in most parts of the country, it is as well to allow for a possible delay in planting out due to cold weather conditions. Tomato plants will not root out into compost or soil with a temperature of less than 14.5 degrees C. For many years I have used 5 inch 13 centimetre pots which produce lovely plants with a built in hold ability.
Tomato plants are known as ‘gross feeders’ but at this stage of their lives they need a potting compost that will feed the developing plant without being too strong that it inhibits extensive root development. Dalefoot Compost for vegetables and salads does this admirably and remains moist between watering.
When the cotyledon - seed leaves of the germinated seedling - start to touch one another it is time to transfer them to their propagating pots. A day before potting up, bring a bag of Dalefoot Vegetable and Salads Compost indoors to warm up. Half fill a 5 inch pot with Vegetable and Salad compost and carefully lift the seedling with as much root ball as possible into place in the pot adding compost to fill it, then gently firm the plant in position. Add more compost if needed and give a little water so the compost is uniformly moist.
Place the pots in the best spot to get the most available light. Ideally, if possible, keep the plants as near to a temperature of 19 to 21 degrees Centigrade by day and 13 to 15 degrees Centigrade by night to produce sturdy plants. When the leaves of the plants start to touch, space the plants out to give them more room to develop.
Terry's top tips, 4. Planting
To produce a heavy crop of delicious fruit, a tomato needs a healthy root system with a mixture of deep plant-anchoring roots and fibrous feeding roots.
Plants growing in the greenhouse or outdoor beds have access to space to develop their root system. The roots of a vigorous variety can extend up to six feet. Roots confined to a pot, container, or growbag, mainly grow plenty of fibrous roots to take advantage of every bit of space.
A healthy greenhouse soil enriched with a large bucketful of Dalefoot Wool Compost for Tomatoes per square yard should provide sufficient nutrients for the season without the need to add fertiliser. A simple pH test showing a pH of between 6 to 6.75 is fine. When half the propagated plants are showing one open flower it is time to plant them all.
When spacing most greenhouse varieties aim for between 15 to 18 inches (38-45 cms) between plants with 15 inches (38 cms) between double rows. A week or 10 days before planting, check the temperature of the soil in the border, 6 inches down, it is easier with the soil thermometer but an ordinary air type handled carefully will do the job. Tomatoes plants will not root out into soil at a temperature of less than 14.5 degrees centigrade If the temperature is below this, ridge up the soil to expose more surface area to warmth, then when warm enough level out and plant the tomato plants.
Terry's top tips, 5. Support
When your first tomatoes start to form and the plant is carrying four to six trusses, ask yourself ‘just how much does your tomato plant weigh?’ This may sound academic, but it is essential when it comes to support.
At this stage of growth with the weight of stem, leaves and developing fruit, a vigorous variety - and tomato plants growing in Dalefoot Compost are certainly that - can weigh in at 10lbs plus! Weight enough to snap thin twine or kink stems that slip down the canes. After all the efforts of growing them, to see maturing plants collapse is a pitiful sight.
Tomato plants can be securely supported in three ways - strings, canes and spirals. Strings need to be soft yet strong enough to carry the weight. Most spools of jute on offer these days are 3 ply. Specialist suppliers, however, still make 5 ply, this is strong enough for all but record-breaking crops. If only a few plants are being grown the simplest way is to make two suitable lengths of 3 ply, twist it together and make a soft strong cord.
With the string, make a figure of eight loop to allow for expansion and tie it round the stem below the bottom leaves. The top of the twine should be tied to a wire fastened above the plants to the greenhouse structure. The string should then be twisted round the plant as it grows. In a lightweight aluminium greenhouse, the structure may not be strong enough to take the weight and the wire may need fastening to a free standing support dug into the border at the end of the rows.
Canes are often the choice when growing in light structures. Sturdy canes are expensive but when cleaned and stored well should last for years. The plant stem is tied every 12 to 15 inches with either stem ties, soft twine or tape, as illustrated. To prevent a very heavy crop from slipping and kinking the stem, tie a length of soft twine tightly above a cane node then round the stem thus ensuring firm support.
The simplest way of supporting tomato plants by far is with spirals. These are also expensive but should last a lifetime. Some of mine are now 28 years old! The top of the spiral is best held in position with a non-load bearing wire.
Spirals are pushed into place and the plant planted close to them. Throughout the season all that is required once a week is the growing tip of the plant to be gently moved into the centre of the spiral, the plant does the rest of the work. We do not know what the season will bring each year, but a well supported plant should safely carry a very heavy crop.
Terry's top tips, 6 – Watering wisdom for tomatoes.
Water, that vital element, is needed throughout the growing season by tomato plants. Some gardeners have irrigation systems, others hosepipes, but for many it is a tap or a barrel or just a watering can. Regardless, of your watering vessel, the following tips still apply:
Why watering for tomatoes is so important.
Tomato plants need to be consistently turgid. It is the word ‘consistently’ that is important. During the summer of 2020 cases of blossom end rot (BER) were numerous because plants had not had sufficient water. BER is a physiological disorder caused by a shortage of available calcium (via water) in the developing fruit. When the calcium level in the tomato falls below 0.5 the cells at the base of the fruit start to implode and the characteristic blackening at the base of the tomatoes appears. This usually occurs around three weeks after fertilisation when the fruit is developing rapidly, by the time we spot it, it is too late to save the truss.
Terry’s ‘Feel test’.
The answer is to keep the bed, or container or bag consistently moist. When in doubt this is done by the ‘feel test’. The surface of the compost may be dry but four to six inches down it may be wet, so gently feel down into the compost some 4 to 6 inches away from the stem, ideally 6 inches (but up to 8 inches deep) and take a scoop of compost. If it is saturated it has had too much water; if it is dry, too little, but if when squeezed water gently oozes out, it is spot on!
How much to water each day?
With so many variables such as weather patterns, compost, site, volume, it is difficult to be precise about water quantities as a guide. However, during dark cloudy humid weather plants may only need 1/4 pint of water a day but when dawn till dusk sunshine arrives they may need 2 to 3 pints a day to keep the plants turgid, as the season progresses experience will be the guide.
Why Dalefoot Wool Compost for Tomatoes helps saves energy when watering.
On the bag of Wool Compost for Tomatoes are the words ‘reduced watering’ and while the composts are not advertised as energy saving in practise that's exactly what they are! A two-gallon metal or strong plastic watering can weigh between 22 to 25 llbs. Before you know it, 20 trips backwards and forwards and we have carried a quarter of a tonne of water! Dalefoot Composts really do save water and our energy.
Next Time, growing late tomato varieties to extend the season.
Terry's top tips, 7 – common problems; leaf curl.
We all look forward to long summer days, but for our tomato plants this means short nights when there are not enough hours of darkness to process all the sugars made during the long days. By high summer our plants, depending on variety, are five to six foot tall carrying leaves in full growth and we notice that some of the older leaves are starting to curl inwards.
Leaf curl is not a disease, it is a physiological condition caused by several factors:
There’s a wide difference in greenhouse temperatures between dawn and noon, this is where automatic ventilators really come into their own. Researchers tell us that when a tomato leaf is 32 days old, its photosynthesising capability is down to 10% of its best which is when it is 3/4 expanded.
Assimilated sugars are transported round the plants to feed the growing cells. Surplus sugars are stored in older leaves and eventually turn to starch and become immobile. As the cells on the underside of the leaves elongate, they push the leaves into rolls. At this stage of growth the plant has ample actively photosynthesizing leaves and the bottom curled leaves can be removed.
Leaves are removed up to a ripening truss, from now on and for the rest of the season, with the leaves being cut off with a sharp knife through the collar where the petiole joins the stem. If the job is done early in the day the wound has plenty of time to callus over before nightfall, reducing the risk of disease entering the plant. This is particularly relevant during September, should a period of damp, warm, ‘fungus’ weather arrive. If curled leaves are left on the plant they become a ‘safe haven’ for pests. Once tomatoes have reached the mature green stage, it is warmth that triggers the ripening process and with the bottom leaves removed, warm air can circulate freely and speed up ripening.
Terry's top tips, 8 – Ripening.
Walk into the greenhouse or to the outdoor tomato bed and pick a warm sun ripened succulent tomato, bite it and as the juice flows into your mouth savour one of the epicurean delights of summer.
Tomato flowers, fertilised in June, produce ripe fruit from August usually when both day and night temperatures are warm enough to trigger the ripening process. Once the tomatoes are at the mature green stage they are old enough to ripen. The optimum ripening temperature for many varieties is 68 degrees Fahrenheit or 20 degrees centigrade, but most will ripen in the temperature range of 65 to 75 degrees Fahrenheit or 18 to 25 degrees centigrade.
Cherry size fruit ripen in some 6.5 to 7.5 weeks after fertilisation. Average size fruit take 8 weeks to ripen. Beefsteak tomatoes take longer, depending on the variety and the weather, ripening in around 8 to 9 weeks plus.
Plenty of sunshine makes plenty of sugar, mainly in the form of fructose which is found in the pericarp tissue of the tomato – that band of fruit flesh just under the skin. The acid content of the tomato is mainly found in the locular (pulp and seeds) centre of the fruit mostly in the form of citric acid with the actual amount influenced by the potash status of the plant.
Why won't my tomatoes ripen? This is a cry often heard during a prolonged spell of dark cool summer weather. Firstly, are the fruits old enough? Then, are they warm enough? To increase the flow of warm air that is available in the greenhouse, remove the bottom leaves up to the first truss. From now on for the rest of the season regularly remove the leaves up to a ripening truss. Cut through the collar of the leaf’s petiole where it joins the stem with a sharp knife. When this is done early in the day the wound has time to callus over before nightfall to minimise the risk of disease entering. When leaves are merely broken off, the larger wound surface area is open to any bought in Botrysis cinarea spores that may be floating about, and these will enter the wound and rapidly multiply and eventually eat right through the stem, producing millions of spores before the season's end.
Small circular spots sometimes seen on a tomato fruit variously called ‘ghost or water’ spots are caused by botrytis spores entering the fruit and the fruit reacting by putting a ring of protected cells around the entry point. Although still edible, after a bad attack the fruit looks awful. Any dead plant tissues seen covered in grey mould of Botrysis cinerea should be very carefully removed to prevent the spores from ‘flying’ as the season still has a long time to go.
By following Terry’s advice, from plant support, through watering and disease prevention, you’ll be able to produce a healthy crop of fruit and enjoy eating lots of tasty tomatoes.