Everyone loves growing tomatoes, but many problems come along with them. Here I will jump into the most common problems you will likely encounter and offer simple solutions to each.
Nutrient Deficiencies
Some of the most common issues with tomatoes are actually caused by nutrient deficiencies rather than pests or diseases.
Blossom End Rot
One of the more common issues you will encounter when growing tomatoes is blossom end rot. The end of the fruit goes dark brown and rotten, just as you are starting to get excited about harvesting them.
This certainly looks like a disease; some people mistake it for blight, but it is a calcium deficiency.
Immediately most people think they need to add more calcium to their soil, but this is unlikely to be the cause of the problem.
Most soil has plenty of calcium for tomatoes to be perfectly healthy, rarely, your soil won’t have enough.
So what is the problem? It is usually a watering issue. Your tomatoes take calcium up through their roots; if there is not enough water, they can’t take up enough calcium. This is a common problem with grow bags, where it is hard to give tomatoes enough water.
Solution
Water more regularly, ideally, tomatoes should be watered every day through summer. This is often easier said than done. If you are growing in bags, then using one of these nifty gadgets below can really help out.
- Specially designed pot for growing in growbags
- Set of 6, measuring 26 centimetres across, so three fit neatly on a growbag
- The inner and outer watering troughs make feeding and watering easy
If you are sure a lack of calcium is the real culprit, then baking some eggshells, crushing them into a fine powder and adding this to your soil can add lots of calcium.
Magnesium Deficiency
This shows up as yellowing leaves, but the capillaries will remain green as you can see above.
It can often happen if you overfeed your tomatoes, as high potash levels can inhibit magnesium uptake.
The yellowing leaves can look very similar to mosaic virus and can cause serious alarm.
There is one easy way to cure this and that is a foliar-applied spray of diluted Epsom salts. Mix some into a spray bottle and regularly mist it over the leaves.
Pests
Whitefly
Whiteflies are a common problem on many plants grown in greenhouses. They can quickly take over a leaf and a severe infestation can cause serious damage.
You can introduce predators to deal with the problem or use sprays. I always try and avoid sprays where possible and if they are needed then try and use an organic one.
Parasitic wasps hunt whitefly and can be introduced to your greenhouse by purchasing them in pupae form. These cards are a handy way of adding them to your greenhouse.
Whitefly Killer Cards are supplied with tiny parasitised Whitefly pupae attached within them. 10 strips will hatch 3,000 parasitic wasps and 50 strips will hatch 15,000 parasitic wasps (as an indication of encarsia numbers)
Caterpillars
Caterpillars can be a serious pain when growing tomatoes, and this is one problem I had to deal with last year.
The easiest method for dealing with them is to remove them by hand whenever you see them. I pull them off the plants and chuck them on the compost heap where they can chomp away or get eaten by the birds, I’m not bothered!
Shaking your tomato plants is a good way to check for caterpillars and dislodge any that may be hiding. If some do fall off then give your plants a thorough check and you will likely find many more.
Slugs
Slugs will happily munch on tomatoes and can cause a lot of damage, particularly to young plants.
Look out for the telltale slimy trail to see whether slugs and snails are your culprits.
If you do have a slug problem, then I have lots of solutions you can find here.
Tobacco Hornworm
I have included this for any American readers, luckily it is not something we have to deal with in the UK, so I have no personal experience of dealing with them. I do know they can cause severe damage though.
I don’t want to offer any guidance, having never encountered them myself, but there is a good guide on the spruce here.
Disease
Tomatoes can suffer from a myriad of diseases, let’s look at some of the more common ones below.
Blight
The dreaded blight, if it arrives there is not much you can do about it after the fact, it will wipe your crop out.
Blight is spread by fungal pores and usually arrives later in the year although this can vary.
Because of how it spreads outdoor-grown tomatoes are much more susceptible than greenhouse-grown ones.
It can be more of an issue in some areas of the country than others. If you are regularly affected then there are varieties that are less susceptible than others and you can also try fungicidal sprays, although they are not always effective.
Mosaic Virus
This is a common virus that affects tomatoes, so called because of the mosaic-like pattern it leaves on infected leaves.
Apart from the leaf markings, also look for strange, stunted growth and brown spots on the fruit.
If you have mosaic virus, there is nothing you can do for the plant. It should be removed and destroyed – don’t add it to your compost.
Clean any tools you used and also your hand thoroughly before using them again, as this is one of the common ways this virus spreads.
If your plant looks healthy but has yellow leaves with green capillaries then your problem might be a magnesium deficiency instead, I talk about this earlier in the article.
So there we have it, lots of problems but thankfully most have a solution. If you have a tomato problem I’ve not listed then let me know in the comments below and I will do my best to help you out!