If you missed the first of this two-part series, you can find the first part here. What we will talk about here are the ways to grow tomatoes; and the pests and diseases that may attack them. This will not be comprehensive – if you have questions, please research further or send us an email with specific questions. If it is regarding a disease on the leaves or fruit, please send a photo to help us identify it.
HOW TO GROW TOMATOES
Tomatoes come from central and and the northern parts of the south American continent, so they are tropical plants. If you are starting from seed, the soil temperature needs to be at least 15°C. However, seed will germinate faster at soil temperatures between 25°Cand 30°C. If air temperatures are cool overnight, soil temperature will also drop. If the soil gets too cold, the seed may die. Seedlings will become stunted and may not continue growing. We have had seedlings that have germinated, grown to 4cm tall and sat like that for weeks before dying.
If you want to start sowing early, keep the seedling trays inside, on a heat mat, or in a glasshouse or cold frame. Unless these are heated, they will only be a couple of degrees warmer than the air temperature outside.
Once the seedling has germinated, you need to keep it warm enough to keep it growing. As mentioned above, if they stop growing, they may never start again and can last quite a long period of time before giving up and dying. Feed your seedlings every fortnight with a liquid feed. You could even try a seaweed tonic in the weeks in between.
When seedlings are 15-20cm tall, they are big enough to go in the ground. Some people wait until they are 25-30cm tall. By then, the soil of your garden is usually warm enough for them to overcome transplant shock quickly and get growing again. Don’t forget to water them in with a seaweed solution (as per manufacturer’s instructions) when transplanting, This spring and summer have been very wet and, as a consequence, the soil temperature in our gardens is still quite cool. If your seedlings don’t start growing, try sowing some new seeds, directly where you want your plants to grow. It’s late in the season but you might be lucky!
As I said in the previous post, tomatoes come in two types: bush (determinate) and vine (indeterminate). You can plant bush tomatoes in a large pot (at least 40cm across) or in the ground. Bush tomatoes do need staking so provide one at the same time as you are transplanting to avoid sticking the stakes through the root ball later. Vine tomatoes should go in the ground, at a minimum distance of 30cm apart. However, growing them this close together will result in less yields than plants separated by the correct distance of 1.0-1.2 metres.
Tomatoes can be grown in tomato cages to keep them off the ground and to stop them sprawling everywhere. These can be bought at hardware stores and garden centres, and generally consist of uprights and side bars that acts as the “cage”. they can be improvised with stakes and string, or a cage made of chicken wire. You can do this for individual plants or grow tomatoes in a row and make a large cage to go around them all.
You can train tomatoes against a fence or trellis in an espalier-style. This is good in a small courtyard and it keeps the plants more two-dimensional and so saves space. To keep this ‘flat’ you will need to control the growth of laterals or side-shoots. This is explained in the next paragraph.
We grow our tomatoes on a specially designed trellis system. It consists of three posts and a bar across the top, 2.4 metres above the soil. A string is anchored to the ground near the seedling and the plant is trained around the string (which is attached to the cross beam above). The plants are grown 30cm apart on one leader. This means we control our tomatoes to one main stem by taking out the laterals – the growth between the leaf and the stem. We pick these out with our fingers but, if we miss them and they get too large, we cut them out with snips or secateurs.
Tomatoes are very heavy feeders. Make sure that your have added plenty of organic matter to your bed before planting tomatoes so that they get that slow release of nutrients. In addition, in the early stages, a general feed, which is high in nitrogen that promotes green, leafy growth, is fine. However, to produce flowers and fruit, the plants will need a feed which is higher in phosphorus.
There are many tomato feeds on the market. We grow without chemicals, or ‘beyond organic‘, so we don’t add anything to our garden, except a liquid fish-based ‘fertiliser’. If you choose to do so but don’t want to go down the industrial, chemical path, make sure you are buying an ‘organic’ product. Always follow the manufacturers’ directions when using the product.
PESTS ON TOMATO PLANTS
For us, the biggest ‘pests’ on tomatoes have been birds. They not only eat the ripe fruit, they also eat the leaves. Because we want birds in our yard, we have resorted to netting our vegetable garden. Previously, we put bird netting around tomato cages. What was more effective, was bags around clusters of ripening fruit.
These bags also helped with fruit fly, which are more likely to attack large fruit than cherry tomatoes. If fruit fly is a big problem for you, we suggest you try only cherry tomatoes. If you can find a way to put the bag on so that it doesn’t touch the fruit, it is an effective way to deal with fruit fly. The part of the body they use to inject their eggs into the fruit is quite small and they need to be able to pierce the fruit. If they can’t reach it, they’ll look elsewhere for somewhere to lay their eggs.
We rarely have aphids on our tomatoes. When we do, we flick them off with our fingers and squish a few to attract the ladybirds to the plant. Ladybird larvae love aphids! You can blast the aphids with a hose or spray them with a homemade solution.
We have lots of white flies on our tomatoes but they don’t seem to do much damage so we do nothing to prevent them. A sticky yellow trap will catch them if you have them in large numbers. We try not to use these traps because they also catch beneficial insects!
There are many other types of pests that attack tomatoes but we have not experienced any of them so cannot give you first hand advice.
DIESEASES ON LEAVES AND/OR FRUIT
If the tomato plant is healthy but there is a large, rough or leathery, brown or greyish patch on the bottom of your tomato fruit, it is very likely to be blossom end rot. This will not kill your plant and the top part of the fruit is usually still edible. Please refer to my previous post about this condition in tomatoes.
Before I discuss diseases on leaves, please check your plants. Is the new growth growing normally , with relatively dark green leaves that lie properly, not curled up? Is it only the older leaves at the bottom that are turning a yellowish colour and looking ‘really bad’?
If the new growth is fine and it’s just the old leaves, they are dying of old age. The plant no longer needs them for photosynthesis so it’s dropping off the unnecessary foliage. You can help by removing all the leaves below the lowest hanging fruit cluster.
If the young leaves are looking pale but there is no evidence of any disease, it could be a nutrient deficiency. Tomatoes are very hungry plants so feed it with a good quality liquid fertiliser and also foliar spray (that is, spay the leaves with the liquid fertiliser). Sprinkle around some slow release feed as well – like aged manure, compost (even if it’s not quite finished), Blood ‘n’ Bone, or pelletised chicken manure. Don’t dig it in, let the rain break it down and feed it slowly to your plants.
Tomatoes are, unfortunately, prone to a wide range of diseases. In the wet weather we have been experiencing in western Sydney during Spring and early Summer 2021, that disease is likely to be Septoria Leaf Spot. I posted about this recently, please go the link here.
Tomatoes are susceptible to fungal diseases, bacterial diseases and diseases brought in by insects. It would be impossible for me to do justice to this topic here so may I encourage you to take photos and send them to us for identification. No matter the disease, the management is nearly always the same – and, no, it’s not pull out the plant!
Diseased leaves eventually turn yellow and fall of the plant. It is important, whatever the disease, that you remove the diseased leaves as soon as you see them to stop the spread to the healthy leaves of that plant and other plants. Also,make sure that you pick up the dead, fallen leaves. Fungal spores and insects can live on these, sometimes long after they have fallen. Do not put these diseased leaves in your compost or in the Council’s green waste bin. Instead, you need to solarise the diseased leaves and infected fruit to kill the spores or insects that may still be alive. I have written a separate post detailing instructions for this process.
The home-made sprays detailed on the post about Septoria Leaf Spot may help. If they don’t, they certainly won’t do any harm – unless you use too much full cream milk which, if left on the leaves, may attract a fungal problem you didn’t have!!
Until next Friday….
Happy growing!
Lynne 🍅
DISCLAIMER: The information presented in this blog post is written for general knowledge and/or entertainment purposes only. Please do further research if you are unfamiliar with this plant. While all care is taken to be accurate, Hillside Homegrown & Handmade accepts no responsibility for actions taken by the reader because of information shared in this article.
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