At a glance
- Use the largest pot that fits your balcony: at least 10 litres for compact varieties, better 20 litres or more. The bigger the volume of soil, the less often your water supply swings out of balance.
- Choose a bush or balcony variety, not a vigorous cordon tomato. Compact varieties such as Tomato ‚Balkonstar' or cocktail tomatoes crop most reliably in a pot.
- Watering decides between success and frustration. In high summer that often means daily, always evenly and straight to the roots, never over the leaves.
- From the first flower, feed every one to two weeks with tomato fertiliser. A sunny, rain-sheltered spot keeps blight away.
A sunny balcony is a full vegetable garden, you just have to stock it well. Tomatoes are the most rewarding choice for it: a single well-tended plant gives you kilos of fruit from July to October, fruit that tastes of sun instead of the chiller shelf.
The difference between a struggling and an overflowing pot tomato rarely comes down to the variety alone. It comes down to three things: enough root space, reliable water and the right spot. Get those under control and the rest almost takes care of itself.
The pot matters more than the variety
The most common cause of limp balcony tomatoes is a pot that is too small. In little soil the moisture keeps swinging: bone dry at midday, soaking wet after watering. That very swing stresses the plant and encourages blossom end rot.
Allow at least 10 litres per plant, and for a strong variety rather 20 litres or more. A large tub forgives you the odd forgotten watering day. Drainage holes matter: waterlogging kills the roots faster than drought.
Which variety belongs in a pot
In a pot you play a different league than in the bed. Instead of the vigorous cordon tomato that grows two metres tall and needs constant care, you reach for compact varieties.
Varieties that work in a tub
- Bush and balcony varieties
Stay low, branch on their own and do not need pinching out. Ideal for boxes and small pots. Examples: Tomato ‚Balkonstar', Tomato ‚Vilma', Tomato ‚Tumbling Tom' for a hanging basket.
- Cocktail and cherry tomatoes
Ripen early and carry many small fruits over weeks. They cope with swinging conditions better than big beefsteak types. Tomato ‚Tigerella' or classic cherry varieties are a safe bet.
If you really want to grow a big cordon tomato in a tub, you can, but only with at least 20 litres of soil, a sturdy stake and regular pinching out. How that works is in Pinching out tomatoes: when and why.
Soil, spot and planting
Use good soil
Tomatoes are heavy feeders. Use a high-quality, peat-free vegetable or tomato compost with some garden compost mixed in. Cheap potting soil is exhausted after four weeks and you end up feeding against the shortage.
Pick the sunniest spot
Tomatoes want at least six hours of direct sun. South- and west-facing balconies are ideal. A spot under an eave or the balcony above keeps rain off the leaves and so helps prevent blight.
Plant deep
Set the young plant a little deeper than it stood in its nursery pot. Along the buried piece of stem it forms extra roots and stands more stable and vigorous.
Support from the start
Push the stake in when you plant, not later between the roots. Even bush varieties like to topple over once they are laden with fruit.
Watering and feeding: this is where it is decided
In a pot the plant cannot draw its water from deep down, it depends entirely on you. This is the point where most balcony tomatoes fail, and the one you can most easily get right.
Blossom end rot is a water problem
A black, leathery patch at the bottom of the fruit is not a disease and not a fungus, but calcium deficiency caused by swinging moisture. The plant cannot move calcium out of the soil when it stands soaking wet one day and bone dry the next. The remedy is not a spray but even watering and a large pot.
- Typ
- Annual fruiting vegetable
- Familie
- Nightshades
- Standort
- Full sun, rain-sheltered
- Ins Freiland
- After the last frosts · CW 19 to 22
- Ernte
- July to October · CW 28 to 42
- Wasserbedarf
- Daily, even, at the roots
Water thoroughly once rather than a little several times, always straight onto the soil and never over the leaves, so they stay dry. In high summer a well-leafed tub quickly needs one to two litres a day, and on hot days morning and evening. A saucer as a small water buffer helps, but should not stand full after a few hours.
Feeding starts with the first flower. The easiest way is liquid tomato fertiliser in the watering water every one to two weeks, or you mix an organic slow-release fertiliser into the soil at the start of the season. Potassium and phosphorus drive the fruit, while too much nitrogen only drives the foliage.
The biggest pot you can carry, and water you can rely on. Everything else is a bonus.
The core rule for pot tomatoes
Basil as a neighbour
Standing a little pot of basil next to the tomato saves space and the two get along well. Both want warmth and sun, and you have salad and seasoning right together. Planted into the same large tub, though, it gets crowded, so keep separate containers.
Frequently asked questions
How big does the pot need to be at minimum?
For a compact bush or cocktail variety, 10 litres is enough, 15 to 20 is nicer. A large cordon tomato wants at least 20 litres. As a rule of thumb: rather one plant in a big pot than two in a medium one.
Do I need to pinch out balcony tomatoes?
Real bush and balcony varieties, no, they carry fruit precisely on their side shoots. If you grow a cordon tomato in a tub, then yes. How to tell the two apart and how pinching out works is in Pinching out tomatoes: when and why.
Why do my pot tomatoes get black patches?
That is blossom end rot and almost always a result of uneven watering in too little soil. A bigger pot, even moisture and a little patience: the next fruits will be clean again.
Can I overwinter tomatoes on the balcony?
No. The tomato is an annual and frost-sensitive, it dies off in autumn. In October harvest the last green fruits and let them ripen indoors. Next year you start with a fresh young plant.
Is my east-facing balcony with only morning sun enough?
It works, but it is tight. Under six hours of sun the fruit ripens more slowly and the plant stays more susceptible. Choose an early cocktail variety that gets by with less, and put the pot in the brightest corner.
Sources
- Blossom end rot on tomatoes and peppers, Bavarian State Institute for Viticulture and Horticulture (LWG)
- Federation of German Perennial Growers: vegetables in tubs and on the balcony
- Related in the magazine: Pinching out tomatoes and The garden in July
Spotted a mistake?
