Growing tomatoes in containers is perhaps the most popular way to grow tomatoes in many countries including the UK.
From grow bags to upside-down planters, and lots of pot sizes in between, containers are so convenient when it comes to growing tomatoes and many other fruit and vegetables too!
Some of the benefits of containers include:
- Can be placed anywhere in the garden, patio or balcony.
- Grow bag soil and potting compost is free from disease.
- Plants can be moved into the sun, shade or undercover depending on weather conditions.
- Most tomato varieties are suitable for container growing – from a trailing variety in a hanging basket to a large tall variety in a grow bag.
Types of Containers include:
Large plastic or terracotta pots – a good way to grow tomatoes – plastic pots are inexpensive.
Air pots – produces very good results by allowing more air into the root zone.
Fabric pots – allows air into the root zone and easy to water in trays.
Grow bags – a container that comes with its own soil and inexpensive.
Grow rings – ring culture normally used with grow bags and improves feeding and watering.
Grow bags cut in half and stood on ends – two heavy duty plastic bags with soil in.
Hanging baskets – best for trailing varieties.
Upside down planters – can be effective but be aware of weight.
Above, air pots enable oxygen to enter into the root zone more easily through the many holes in their side.
Soil – Growing Medium – Substrate
The variety of potting composts at the garden centre seems to increase each season and so does the price!
The most important soil attributes for container growing are:
- Holds moisture well
- Holds air and doesn’t compact when it begins to dry
- Is disease-free
Basically, almost any kind of compost with perlite added will be good, but the more you pay, the better quality you’ll get.
A John Innes mix is excellent for containers because of the quality of the ingredients and the weight adds stability.
Compost for hanging baskets, where weight is an issue, a mix of mutli-purpose and John Innes with added perlite is excellent.
It’s best to add your own perlite – anywhere from 10% and up to 50% of the potting compost/perlite ratio – the more you add, the better the roots will like it!
I should mention that a multi-purpose compost high in peat is undesirable because peat shrinks as it dries and air is removed from around the roots.
The introduction of air pots and fabric pots show us an important lesson in tomato growing:
Roots need air!
More precisely, roots need oxygen and without it, plants won’t grow. It is estimated that tomato plants absorb 98% of the oxygen they need through their roots.
The surface area of a container is usually a lot less than roots require, so the fine surface root will grow round and round at the soil surface forming a tight cap. This prevents air from entering the root zone and often retards plants by starving them of oxygen.
Dirt pots are one of the many makes of fabric pot that allow air to be absorbed into the roots more easily.
Oxygen starved root zones also reduce the uptake of some nutrients – iron for example. Iron deficiency in container grown tomatoes is very common.
More details about container optimisation and nutrient deficiencies will be found in the Newsletter which starts in February.
Potting soil, multi-pupose compost and soil are synonyms in this article.