Keep Tomato Plants Producing All Summer With My 5 Pro Growing Tips
I’ve been growing tomatoes for over a decade and, as a gardening editor, I’ve tried out a heap of expert tips and tricks. These five actually work.
I’ve been a gardening editor for longer than I want to admit, and I’ve been growing tomatoes from the start. My work has meant I’ve been lucky enough to visit goodness knows how many nurseries and talk to a gazillion professional growers, and I’ve hoovered up tips and tricks the whole time. So believe me, I’ve tried out way more than my fair share of professional hacks in pursuit of a perfect crop of juicy toms that keeps on coming all summer long.
And yes, as a regular Instagram scroller, I’ve tried out plenty of unprofessional tips too. Honestly, quite a few of both types turned out to be absolute hogwash. Some had the potential to be downright deadly (here’s looking at you, baking soda making tomatoes sweeter). But a few actually worked.
Heeding tomato care basics such as supporting and pruning tomato plants will bring you a decent initial crop of tomatoes. But here’s the thing: if you want to keep tomato plants producing plenty of tomatoes as the weather gets hotter, foliage and fruit become more susceptible to disease, and sap-sucking insects move in, you need some extra tricks up your sleeve. These days, I only raise six tomato plants each summer because I’m confident – thanks to my trial and error testing of all those hacks – that I can keep them producing bumper crops of toms for months on end. And just look how many tomatoes those few plants produce.
These are those expert tomato growing tips, so you too can harvest more than ever before.
1. Basil Supports Tomato Plant Health
You’ll hear all sorts of hype about companion plants when growing tomatoes, and mostly they’re used either to attract beneficial bugs or deter pesky ones. But there’s one companion plant that does things a little differently and it's an absolute must, because basil directly increases tomato yield by as much as 20%. Scientists have shown that basil releases volatile compounds that prime a tomato plant’s defense mechanisms. So, if a tomato plant is attacked by pests or disease, if it’s got a wingman basil plant growing next to it, it’ll react to that threat faster and more robustly.
Research proves that growing basil alongside a tomato plant helps it grow stronger roots, too, that allow it to cope better with drought and heat. Basil also helps to attract pollinators and deter pests, and even makes fruit taste sweeter.
There are around 150 types of basil and for the full benefit, it’s best to grow a few varieties. Greek basil (Ocimum minimum) is the variety used in the stress-reponse study and seeds are available from Amazon. Purple basil (Ocimum basilicum var. purpurascens) has an intense aroma so is particularly effective at repelling pests, and seeds are available from Eden Brothers. Lemon basil (Ocimum x africanum) is the variety used in the study that found basil can improve tomato flavor perception, and seeds are available from Botanical Interests.
2. Banana Peel is Full of Potassium That Tomatoes Need
You’re likely feeding your tomato plants every 10-14 days with a liquid fertilizer that’s high in potassium, like this Espoma Organic Tomato Feed from Amazon. Plants need many nutrients for healthy growth but broadly speaking, nitrogen promotes leaf and stem growth, phosphorus aids root development, and potassium helps flowers and fruit form; these are collectively known as the NPK ratio.
And as luck would have it, banana peel is super-high in potassium, and you can use it to give plants an extra boost with a mild, slow release of nutrients. Some people mix chopped-up banana peel into the compost at the base of planting holes when moving tomatoes outdoors. I choose to make a supplementary banana peel tea whenever the opportunity arises, steeping a couple of chopped-up peels in a quart-jar of water for three or four days, then pouring the strained tonic onto the soil, diluting first if it looks strong.
Banana peel also contains a small amount of calcium, which helps prevent blossom end rot (which causes those leathery black patches on tomato bases), and trace elements that support photosynthesis. Importantly, it doesn’t have any nitrogen, so won’t fuel leafy growth.
3. An Electric Toothbrush Improves Pollination
Tomato flowers need to be pollinated before they can set fruit. Happily, each flower contains both male and female parts so all that needs to happen is a little movement to shake the pollen free from the male anther cone and onto the female stigma. If you’re growing tomatoes outside then buzzing insects and the wind will naturally ensure this little jiggle happens. But, if you’re raising your toms on a kitchen windowsill or in a greenhouse, your plants could probably do with a little pollinating help.
Flowers can increasingly fail to pollinate as summer temperatures heat up, too. Once daytime temperatures are above 90°F or if it's over 70°F at nighttime – and remember, greenhouses can be far hotter than the air outside – pollen can become too dry or sticky to easily be distributed. Those flowers that dry up and drop off your plants? They're likely to be the blooms that failed to pollinate and, as the season progresses, you’ll see an increasing number of these on each truss.
Unless, of course, you employ an electric toothbrush to deliver that essential buzz. Hold the back, non-bristly side of the toothbrush head gently against the stem directly above each flower for a couple of seconds, when conditions are dry. Tomato flowers only have a 50-hour window for pollination so, to get full trusses across all your plants, you’ll need to do this every two days. You can buy super-cheap rechargeable electric toothbrushes such as this from Amazon, so don’t even consider using your own!
Shading plants in a greenhouse from the midday sun will also help pollination rates. Opt for 40-50% sunblock so plants still get plenty of sun to photosynthesize, with a shade cloth like this from Amazon, and position it so it only blocks the strongest overhead midday rays.
4. DIY Drip Irrigation is a Game-Changer
Let’s be honest, how regularly do you water your tomato plants? Most toms are on a rollercoaster ride between saturated and dry soil, and one of the most important things you can give a tomato plant while it’s fruiting is consistent moisture. Any big swings in soil moisture stresses plants, leads to blossom end rot, and cracked, split fruit. A dehydrated plant may also drop its flowers.
Drip irrigation systems are great, but there are lots of other, cheaper ways you can stabilize soil moisture between waterings or rainfall. I’ve DIYed drip irrigation systems from upcycled pop bottles, and you can see how I made them here.
I now also use clay LECA balls such as these from Amazon as pot-toppers to regulate moisture, and I DIY sunken water reservoirs alongside my bigger tomato plants to mimic how ollas (like these from Amazon) work. Mixing coconut coir such as this from Amazon into the soil is another way to help it hold onto an excess of water then release it slowly.
Yes, I water just as often, but the soil is delivered to my plants far more evenly and that means they’re far less stressed. It also means that I can go away for the weekend without having to ask my nosy neighbor to water my precious toms, so I'm far less stressed, too.
5. Stopping Feeding is as Important as Starting Feeding
We all know we need to feed our tomato plants to produce lots more fruit, and to start as soon we spot the first flowers. But when do you stop feeding? Because if you carry on feeding too long, you encourage the plant to pointlessly keep on growing rather than directing its energy into ripening the existing fruit.
You should stop feeding around a month before your first expected frost, or once nighttime temperatures start to dip below 50°F. At this point, snip off the top of the main growing stem(s) too, known as ‘topping’. This stops the plant growing upwards and forces it to direct all its energy into ripening its existing trusses of tomatoes.
