Tomatoes

As soon as I could afford it, I bought a small “lean to” greenhouse for my garden.  And as soon as I had a greenhouse, I started growing tomatoes!  Even in a normal seed catalogue, there’s a startling variety of tomatoes to grow.  But through my Heritage Seed Library membership I have been able to find even more wondrous varieties!

Following the “standard” approach of growbags or compost in pots, I was able to get a nice supply of tomatoes in August/September each year, despite the inevitable catastrophes of the drip irrigation system clogging during the occasional blazing hot weekend when I wasn’t home (it feels like these things never fail when it isn’t catastrophic!).  However, some years the harvest was as low as 40g per plant.  Some years I had problems with split tomatoes and I was aware this was probably because there had been a gap in watering when the tomatoes were close to ripe, which caused the tomatoes to split when watering resumed.  It was obvious that there was room for improvement in my approach!

2020 was the magic year when I got a new greenhouse with better fitting glass, which made it possible to start the growing season a bit earlier.  It was also the year that I started to experiment with hydroponics and autopots (see previous posts on cucumbers and peppers).  From then on, the majority of my tomatoes were grown in autopots with the occasional “normal” pot thrown in for comparison.

Autopot Comparison with “normal” pot

In 2020 I grew Sweet million in an autopot and in a normal pot in the greenhouse.  I got nearly 4 times the harvest from the plant in an autopot.  Similarly the Sugar Plum Raisin I grew in an ordinary pot only achieved 1/6 of the harvest of the same variety in an autopot. Based on that success, I grew Moneymaker in an autopot in 2021 and doubled the 2020 harvest (from 5 plants) with a single plant grown in a small autopot! 

Hydroponic Comparison with “normal” pot

Also in 2020, I grew a Super Sweet tomato plant in a Deep Water Culture (DWC) hydroponic system (effectively a tub of water oxygenated in the same way as a fish tank with an air pump driving air through an air stone).  I grew a comparison plant in a normal pot in the greenhouse.  These results were more marginal.  I did get a bigger crop (0.393kg) using hydroponics compared to the pot (0.254kg), but neither plant looked particularly strong. 

I didn’t continue with hydroponics as I found keeping the water chemistry in trim was very time intensive.  Keeping the nutrient proportion was fairly straightforward.  However, despite my efforts, it wasn’t possible to prevent the water getting too alkaline every day from the air blowing through. 

One summer of experimentation was enough to convert me to autopots rather than DWC hydroponics because:

• The substrate in the autopot protects the roots, so pH control is not so critical as in DWC
• Although airflow can be introduced to the roots, plants grow successfully without – so that’s an opportunity to reduce energy consumption
• The substrate in the autopot allows the plants to form a rootball which helps stabilise them (although I provide plenty of string for the vines to climb up)
• Less worries about waste.  For DWC it is recommended to dump all the nutrient water every 7-14 days.  As this water contains fertiliser, it shouldn’t be allowed to reach any watercourse and contribute to eutrophication (which is already high in my area).  For that summer, I decanted the nutrient water into buckets and used them to water pot plants in my garden, but that (along with the scrubbing) was more work than I had time for.

Growing

Most years, I grow my own tomatoes from seed and try to get them started in the autopots by April.

Progress can vary a lot between species. In July, the Sugar Italian Plum was showing flowers at the same time that White Queen had well developed fruit.

White Queen spent summer 2021 looking a bit straggly (mainly due to my lack of time to train it properly) but gave a decent crop. While Chocolate Cherry looked very healthy all summer, but wasn’t quite as productive.

To avoid having too many green tomatoes at the end of the season, it’s worth removing all the new growth with flowers once a good crop of tomatoes has set. This lets the plant focus on ripening the existing tomatoes.

Harvest

Harvest is always a rewarding time of year! Although it’s not always this picturesque!

If the plants are producing more than can be dealt with at any time, it’s a relatively simple task to freeze the spares on a tray then decant into an airtight tub (still in the freezer) for a mammoth chutney making session later on. There are so many recipes for tomato sauces, chutney, relishes, jams and jellies that no tomato needs to be wasted!

Yield Summary Table

The following crops were grown in autopots unless otherwise stated.

Crop	Year	Soil area (m2)	Soil depth (m)	Annual harvest (kg)	Mass Yield (kg/m2.d)	£ yield (£/m2.d)	Calorie space* (m2)	Protein space* (m2)
Big Daddy	2022	0.04	0.25	3.578	0.376	1.026	453	227
Chocolate cherry	2021	0.09	0.3	2.359	0.116	0.318	1547	774
Estonian yellow	2022	0.09	0.3	2.333	0.109	0.297	1565	782
Gardener’s delight	2022	0.09	0.3	5.425	0.252	0.691	673	336
Indigo blue berries	2022	0.09	0.3	4.008	0.421	1.149	405	202
Money maker (5 normal pots)	2020	0.245	0.22	1.977	0.045	0.123	5034	2517
Money maker	2021	0.04	0.25	4.018	0.461	1.258	404	202
Sugar Italian plum	2021	0.09	0.3	1.168	0.068	0.186	3125	1562
Sugar Italian plum	2022	0.09	0.3	4.625	0.216	0.589	789	395
Sugar plum raisin	2020	0.09	0.3	3.763	0.202	0.551	970	485
Sugar plum raisin (1 normal pot)	2020	0.017	0.15	0.579	0.182	0.508	1238	619
Super sweet (DWC hydroponic)	2020	0.05	0.15	0.393	0.037	0.100	5325	2662
Super sweet (1 normal pot)	2020	0.017	0.15	0.254	0.817	0.223	2822	1411
Sweet million	2020	0.04	0.2	1.41	0.170	0.465	1150	575
Sweet million (1 normal pot)	2020	0.017	0.15	0.383	0.123	0.336	1871	936
White Queen	2021	0.09	0.3	3.131	0.198	0.540	1166	583
White Queen (new greenhouse)	2022	0.09	0.3	5.231	0.244	0.667	698	349
White Queen (old greenhouse)	2022	0.09	0.3	8.296	0.387	1.057	440	220

As indicated earlier, the autopots consistently gave better yields than ordinary pots or even DWC hydroponics. However, this isn’t the only yield factor. Even in a greenhouse, the weather has a major influence on yield. 2022 was definitely a tomato friendly summer! Now that I’m getting used to the seasons, I aim to have my last harvest in October as the plants really deteriorate in the colder weather.