[Fishplate42]

How do I grow semi-determinate tomatoes?

I have been growing tomatoes for years, but usually the same old varieties. This year I plan to grow Roma as this is a plum tomato ideal for making sauces. Most of the tomatoes I have grown in the past have been indeterminate varieties. I have grown a few determinate varieties, and I get that, but how do I grow semi-determinate types? Do I grow them as determinate, but with some support, as a semi-determinate tomato will grow as a determinate with longer branches?

Ralph

[mumofstig]

The plants will grow several 'branches' but these branches will not necessarily end in a terminal truss, like determinate plant should do. Some of the branches may give 2, 3 or more trusses (if you're lucky  )

I always start with 3 waist high canes around the plant, tied together with baling twine, but be prepared to add in some more tall ones, if any of the branches get extra long and need tying in under each truss.

[Fishplate42]

Thanks Lesley, that makes sense. I will give it a go. I assume the plants will need to be spaced out further than my normal 18 inches apart, 24 inches between rows I use for the indeterminate varieties. What spacing would you recommend?

Ralph.

[mumofstig]

I get 4 down the length of the greenhouse, so one per 2ft glass panel, and about the same outside, but maybe a bit more space between the rows cos they do grow quite bushy in a good year.
Good luck!

[lettice]

Have not grown Roma for a long time as have for many decades grown my now preferred San Marzano for my paste/sauce tomatoes.

For Roma I only grew outside in pots. They were very bushy and produced well, but did not crop as long as my San Marzano. Roma cropped from July to September, whereas my San Marzano crops from mid June to mid November.
The San Marzano in my opinion is meatier and makes for a better paste/sauce tomato. Still I had many reliable years of growing Roma and using for paste/sauces
I use to allow about five or six flowered trusses and pinch out the tops
I did pinch out alternate side shoots as they did become very bushy plants.
They needed staking and did much as mentioned above, four stakes in the pots with string around.

[Fishplate42]

Have not grown Roma for a long time as have for many decades grown my now preferred San Marzano for my paste/sauce tomatoes.

For Roma I only grew outside in pots. They were very bushy and produced well, but did not crop as long as my San Marzano. Roma cropped from July to September, whereas my San Marzano crops from mid June to mid November.
The San Marzano in my opinion is meatier and makes for a better paste/sauce tomato. Still I had many reliable years of growing Roma and using for paste/sauces
I use to allow about five or six flowered trusses and pinch out the tops
I did pinch out alternate side shoots as they did become very bushy plants.
They needed staking and did much as mentioned above, four stakes in the pots with string around.

Thanks for that, most helpful. I think I will grow my Roma in pots in front of our south-facing shed. I have a packet of San Marzano 2 that I will use outside. Do you know what the difference is between 'San Marzano' and San Marzano 2', as my packet says the latter?

Ralph.

[mumofstig]

The original San Marzano wasn't resistant to Mosaic virus, so eventually they hybridized  it until they got the resistance, and named it number 2 

[jambop]

I grow Roma every year in the open ground. It is a fantastic tomato and very reliable. I plant them about 50 to 60cm apart and put a decent stake in at planting then as the plant grows hold the plant to the stake with twine at points in time it keeps the plant upright and takes the strain off the main leader a bit and keeps the fruit off the ground DO NOT REMOVE SIDE SHOOTS and look forward to a great crop of tomatoes for canning or juice and sauce making.

[Subversive_plot]

I only grew Roma last year. My growing conditions are different from yours, but what I suggest is using wire tomato cages that are roughly chest high (you can buy, or make from wire fencing). For extra support, place a taller stake firmly into the ground, inside the tomato cage.

That taller stake can be used to tie up any branches that exceed the height of the tomato cage.

My conditions (in Georgia, USA) might produce bigger, taller plants though (more sun, warmer, longer growing season). So, local advice may be more reliable in terms of expected plant size.

An odd characteristic I observed this past year is that I often got trusses that bloomed in summer that might, (for example) have 8 flowers, producing just 5 fruits (3 flowers dropped, apparently "barren"). After those 5 fruits ripened and we're picked, the remaining 3 fruits developed later!!! Often these had few seeds or no seeds. Virtually all my Romas did this last summer, giving me an extended crop. Side shoots also bloomed and produced many tomatoes.

Unless you know for sure that your soil is neutral to slightly alkaline pH and calcic, providing plenty of calcium will give you better yields, less blossom end rot.