Do This 5-Minute Task in September to Guarantee Your Tomatoes Ripen Before the End of the Season

It is time to show your tomatoes some tough love, as September is the month to start topping tomato plants to guarantee your late-season harvest. Stopping plants in their tracks is never the most enjoyable task of the season, but it comes with tangible rewards.

The priority when growing tomatoes shifts come September. You don’t want to encourage lots of new growth; instead, the focus is on ensuring plants can ripen all the fruit they already have before the end of the season. This is done by topping tomato plants and removing the growing tips.

It is a quick, simple task for a pair of sharp pruning tools (I will top my tomato plants in the coming days with my Felco pruning snips, available at Amazon). It always feels a bit harsh to top plants you have lovingly nurtured for months, so I want to show the benefits of topping tomato plants and when you should do it.

Should You Top Tomato Plants?

Yes, I am convinced that gardeners should top tomato plants at the latter end of the tomato season. I have grown lots of tomato plants over the years, from a greenhouse with 80+ plants that we cropped for a restaurant, to a few tomato plants in pots on a patio at home. This has always been in US hardiness zone 8 in the UK, where the season is relatively short, especially when my tomato plants were outdoors.

Come September, the season starts winding down from the summer peak. Healthy, prosperous tomato plants may have produced a lot of fruits so far, and still have lots of young tomatoes developing. This is where topping tomato plants is hugely beneficial in helping those existing tomatoes to ripen.

Without any intervention, indeterminate (or vining) tomato varieties will continue growing until the plant is naturally killed by frost. The plant will grow taller and develop more flowers and little fruits. Unless you are in the warmest climates, or have the luxury of a heated greenhouse that can provide warmth and year-round artificial light, any new fruits won’t have time to ripen.

Topping tomato plants focuses the energy. The plant puts all its energy into swelling and ripening the fruit it is carrying, rather than relentlessly growing new stems and charging upwards. At the end of the season, this helps guarantee that your fruits ripen before the cold weather arrives and growth stops.

Another reason to top tomato plants is to keep plants under control. I have not always had the luxury of super-tall greenhouses. I have topped plants once they reached the roof of smaller greenhouses, especially when using plastic DIY greenhouses on a patio or in a courtyard garden. For example, I have had great success using a plastic walk-in greenhouse like this at Wayfair at home in the past.

After topping tomato plants, they will likely continue producing side shoots in response to being pinched back. Continue to monitor plants and prune tomato plants regularly, as removing these side shoots keeps the energy focused on developing fruits.

When to Top Tomato Plants

The ideal time to plan for topping tomato plants is around 4-6 weeks before your first anticipated frost. This leaves enough time in the growing season for the last of your fruits to ripen (hopefully).

For growers in many US hardiness zones, September is the month to do this. It may be early in the month in zones 5, 6, and 7, and more towards the middle for zones 8 and 9. Check your weather predictions and make sure to top plants at least four weeks before the first frost.

Also, I have had years when tomato plants have been slow, and the fruits simply didn’t ripen as quickly as I’d hoped. When this has happened, I have topped plants a bit earlier to revive my tired tomato plants and focus the energy they do have on giving me a decent harvest of tomatoes.

How to Top Tomato Plants

Topping tomato plants is super quick and easy. It is better to use a pair of clean, sharp pruning tools – pruning shears (you can get lightweight, sharp pruners at Burpee), pruning snips, or garden scissors – rather than snapping or tearing the stem by hand, which risks damaging any trusses further down the plant.

Take your pruners and cut the growing tip a couple of leaves above a fruit truss. A healthy plant should develop between four and six fruit trusses in a season. If you grow tomatoes in colder areas with a shorter season, it is sensible to expect fewer trusses, around three or four.

Topping plants is only necessary with indeterminate plants, not with determinate (bush) tomatoes. Vining tomatoes continue to grow and produce flowers and fruits over the season. Bush tomatoes grow to a fixed size and fruit over one period – they don’t need pruning over their lifespan.

What to Shop

Topping plants always helps tomatoes ripen on the vine. However, there may always be some tomatoes for which there isn’t time to redden up before the season ends. If the tomato has started showing a faint blush of pink or red, you can ripen it indoors. Place any fruits like this in a paper bag along with a ripe banana. The banana produces ethylene and helps the tomato turn red.

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