How To Sow & Grow Tomatoes

Tomatoes From Seed

If you’re planning to grow in a tunnel or greenhouse sow late February to March which will give you nice plants ready to plant out April – May. If you’re growing outside delay sowing until late March – April which will give you plants for setting out late May to Mid June.

Tomato seed is easy to germinate and grow on provided you practice good hygiene, use the freshest possible seed compost and keep a careful eye on temperature, watering and light.

Sow the seed thinly onto gently firmed trays or pots of compost – about 10 seeds to a 3½" (9 cm) pot or a couple of hundred to a standard seed tray (divided up into varieties if you wish). Cover the seed with a layer of compost roughly as deep as the seeds themselves – sieving compost through an old sieve works perfectly.

Water the trays or pots and stand them somewhere warm and in good light; a constant temperature of 65° - 77°F  (18½°  – 25°C) is perfect so if you have a heated propagator that is ideal, alternatively a warm windowsill will be fine. Putting the tray or pot in a plastic bag is best avoided as this can cause excessive humidity and the possibility of fungal problems. Keep the compost just moist but never soggy wet. At a temperature of 75°F (24°C) they should germinate within 5 - 10 days; a cooler temperature will slow germination and below 50°F (10°C) they will probably not germinate.

Once the seeds have germinated keep a very close eye on them as they can literally romp away into leggy weedy seedlings very quickly. Provide as much light as you possibly can and grow the seedling on at a reduced temperature of around 65°F (18½°C). If you are growing on a windowsill or similar uni-directional light source you will need to turn the growing container several times a day in order that the seedlings do not grow towards the light.

Watering is also important – too much and you will produce weak and leggy seedlings. You are better to let the compost all but dry out before watering again rather than keeping the compost a 'steady moist'. Once the seedlings have grown and produced their first true leaves (their first set of leaves after their seedling leaves) prick out (transplant) your seedling into modules or small pots. If the seedlings are a little leggy you can set them deeper to shorten the height of the seedling.

Growing On (for those purchasing our tomato plants – read from here on !)

Continue growing on the plants at a temperature of 65°F (18½°C) or more and pot on as required so that you end up with individual plants in 3½" (9 cm) pots standing about 6" – 8" (15 - 20 cm) tall - perfect for setting out. If you are planning to grow outside and the threat of frost has not subsided, or you’re just plain not ready to plant out into their final position, pot your plants on again to avoid them becoming root bound and checking their growth.

Planting Out
Tomatoes always do better grown under protection rather than outside due to the increased warmth and the greater control you have on watering. Both greenhouses and polytunnels are absolutely perfect. Whether growing inside or out, your options for final setting out are (1) in the ground, (2) in grow-bags or (3) in pots.

Because of the risk of blight and one or two other nasties it is probably unwise to grow in the ground – if you have grown in a container or grow-bag you can physically take the problem away with little or no chance of long-term soil infection.

Grow-bags are 'ok', but like everything are made for a price (which is usually cheap) and if they have been standing around for some time the nutrients will have released and the compost gone stale.

In our opinion, growing in containers is the best way and will give you the best results (and is how we grow our tomatoes). You can easily make your own compost to fill the tubs by mixing fresh grow bag compost with 25% horticultural grit or vermiculite to add all important drainage and adding 4 oz (113 g) of garden lime per 50 litres of compost.

If growing in grow-bags set out three plants per bag. If growing in containers, a 15 litre pot will be fine for one plant whilst a 40 litre tub is suitable for 2 or 3. Plant firmly and, if the plants are leggy, a little deeper. Cane the plant straight away and water in well.

Training

Despite what many people think tomato training is easy as long as you know what kind of tomato you are growing. Tomatoes can be divided into two groups...

• Bush varieties (sometimes known as determinate as they eventually form a flower cluster at the terminal growing point, causing the plant to stop growing in height).
• Cordon or Vine varieties (sometimes known as indeterminate as they never set terminal flower clusters, but only lateral ones and continue indefinitely to grow taller).

Bush Varieties
Simply tie the plant in to support it and more or less leave it to its own devices. You can thin some of the leaf if you wish to improve air circulation and similarly prune back some of the growth to contain the overall size.

Cordon Or Vine Varieties
The idea is a little different but just as easy. Simply allow the main stem of the plant (the vine) to grow up a cane or string tied to the roof above - tying in as required.

As the plant grows remove all the non flowering side shoots that appear – if you are worried which is which allow them to develop a little more so you are able to see the difference before removing. When the plant has produced sufficient side shoots of flower / fruit (called trusses) you simply 'stop' the plant – by removing the top growing point.

How many trusses of fruit to allow will depend on the variety; generally speaking around 5 trusses is ideal for normal size tomato varieties, 4 or even 3 for large beef tomatoes whilst with cherry and currant tomatoes you can allow 6, 7 or even more.  For the rest of the growing season you will need to keep an eye that further side shoots do not appear and try and grow away – and similarly ensure the vine stays 'stopped'. 

(Note. It’s worth wearing gloves when side shooting, tying in and generally handling tomato plants – otherwise your hands will become covered in a greenish powder that when you then try and wash off goes bright yellow and stains everything – but will wash off / out eventually)

Watering

Water your tomatoes on a cyclic basis – giving them a good drink and then allowing them to virtually dry out before watering again – but never allow them to completely dry out to the point of wilting. Keeping them constantly moist will cause them to grow quicker but the growth will be weaker, so if in doubt keep them on the dry side.

Feeding

Soon after planting into their final position start a feeding regime. Tomatoes are gross feeders but this does now mean go over the top! With the young plants, and before any flower is showing use a good balanced liquid feed once a week or alternatively twice a week at half strength. As soon as the first flowers appear switch over to a feed higher in potash (most tomato fertilisers are) and feed as per their recommendation or experiment by diluting down further but using more regularly. Continue this throughout the Summer.

As soon as the first flowers start to show it’s also a good idea to lime the plants by sprinkling about 2oz (56 g) of lime around the base of each plant as this will certainly do no harm and usually reduces blossom end rot on the first fruits (see below).

Pollinating

Pollination should be something you do not need to worry about as insects, any natural movement of the plants or unnatural movement of the plants by you working on them should be enough to transfer the pollen. If you do want to artificially pollinate, this is easy – simply grasp the plant by the main stem and give it a good shake! You can do this every few days when in flower if you wish but is usually not necessary.

Pest & Diseases

Despite the fact tomatoes can suffer from ‘all sorts of things’, they actually rarely do. Common problems you will come across are…

Blossom End Rot
Not a rot at all! The end of the fruit appears flattened (and sometimes curves in on itself), and goes brown and remains hard. Most commonly this affects the first fruits that set; there is no cure for fruit affected with this but its instance can be reduced. It is not a disease but a physiological condition brought on by a lack of calcium and / or imbalance of potash. Ensuring the compost you plant into contains good amounts of lime and a liming at first flowering reduces the chances of this drastically. Allowing plants to dry out to the point of wilting will also cause greater instance of this so take care with watering.

Greenback
Again, this is not a disease but a physiological condition which causes the top of the fruit and some of the inner flesh to remain green and stay hard to the point of sometimes being inedible raw. You will see this most often in 'bad Summers' as it is caused by low temperatures and low light levels as well as the plants being kept too wet. There is no cure for affected fruits, but it shouldn’t stop you eating them and if the weather improves later fruits will be fine.

White Fly, Aphids and Red Spider Mite
All can affect tomatoes and if you suffer an infestation it is really down to you as to your preferred method of control. Here on the nursery we prefer to deter rather than cure by regularly spraying with our BioFriend Plant Defence- a concentrated garlic and seaweed based mixture which discourages the pests as well as increasing the plants natural constitution so they can ward off invaders. Additionally it is important to avoid excessively high temperatures so make sure there is good ventilation and air flow.

Blight
Blight is a fungal infection spread by wind, rain and rain splash (dormant spores splashed up from the soil), and causes brown spreading blotches on the leaves and stems and brown patches of rot on the fruits – and rapid death of the plant. Outdoor crops are more likely to be affected than those grown inside, though if you water regularly with stored water from a water butt you may introduce the problem inside. Good plant hygiene, care with watering (avoiding splashing the foliage) and care with where the water comes from will all reduce the chances of the problem. Preventative regular spraying with a concentrated garlic solution will also reduce the chances of the problem taking hold as the highSulphurcontent of garlic acts as a natural fungicide. If your plants do become infected with blight you may be able to keep them 'just about going' by spraying regularly with garlic or a copper based fungicide – but you really are better to cut your losses and clear and burn everything and start again the following year.

Watering (again) – Getting The Flavour In The Fruit

If you grow parsnips you should know that they taste better after a frost or two; this is because the frost converts the starches in them to sugars, and sugars = flavour! If you grow peas you should know that a constant level of moderate moisture will give the best flavour; this is because moisture stops the sugars turning to starch in peas, and sugars = flavour! With tomatoes, the flavour (sugars) in the fruit develops when the tomato plants start to dry out – so when some of the fruits on your plants start to show colour take extra care with the watering, and try to allow the plants to all but dry out before watering – but never allow them to completely dry out to the point of wilting. On a side note this answers the age old question as to why most supermarket tomatoes have no flavour - because most supermarket tomatoes are grown hydroponically or using nutrient film technique which means the plants are never short of water and so the sugars and flavour never build.

Harvesting

By growing your own you should be able to allow your tomatoes to fully ripen on the vine before harvesting. It will be pretty obvious when the tomatoes are perfectly ripe – they will be red (or yellow or purple…) and just ‘off’ firm – and if you get down close to them they will smell like tomatoes! Pick as and when you need them. If they start to get ‘ahead of you’ you’re not using enough! You can always use excess by making a basic sauce or puree and freeze it and the slightly over-ripe ones are perfect for this as they have more flavour (and the cooking will kill off any bacteria before freezing). You should never need to let a tomato go to waste!

As they need warmth and good light to ripen, in a poor year ripening can be slow. If this is the case either be patient or pick off a few fruits and bring them into the warmth of the house to ripen. This is something you may need to do with outdoor grown tomatoes but will probably not need to do with those grown under protection.

As the Autumn starts to draw near day length shortens and temperatures reduce – and your remaining fruits will hang ‘green’ on the vines steadfastly refusing to ripen! At this point you are best to cut your losses and pick the remaining crop and either use for chutney or bring into the warmth to ripen.

Clearing Up

Finally, never ever ever compost your spent tomato vines - even if you haven’t seen any signs of blight or disease - the only thing to do with old tomato vines is burn them! The spent compost from your grow bags or tubs can go on the veg or fruit garden avoiding where you plan to grow spuds next year. Here on the nursery we actually use the tubs for over-wintered salad crops and carrots and things, before emptying on the veg garden in the Spring when we re-fill for the next crop of tomatoes.