Tomato soil

[Robert_Brenchley]

How often does the soil in a tomato bed need changing? I've got some large troughs which I could use to grow them, but I'm not looking forward to digging the soil out, and I'm wondering how much I need to do, and how often.

[Robert_Brenchley]

[ACE]

I would think providing you have not had any blighted plants in there it should be good for a few years. The soil is after all just a medium for holding the plant. Loads of chicken pellets and liquid feed next year, perhaps a top dress over winter with some rich dung and it will be ready to go. We have houseplants in pots that keep going in the same old soil year after year until they need repotting all we do is enrich it sometimes with plant food, so if it works for them, why not tomatoes.

[Robert_Brenchley]

I've been told the soil gets poisoned somehow, and has to be changed, but maybe I got it wrong. Blight wouldn't affect the soil, as the fungus is in the tissue itself.

[ancellsfarmer]

Blight is not the only potential problem. Just go to the RHS page on tomato diseases and be scared by the potential pitfalls!!
Sterilizing is difficult, due to constraints of temperature and nonavailability to amateurs of bio-cides, therefore the next option is changing the medium. One-trip containers of your chosen compost, growbags (possibly old compost bags/fertilizer sacks filled with home brew medium), or dig it out and replace. Remember greenhouses and tunnels could be fumigated, spidermite is a frequent issue , viruses and moulds are there as well.

[Tee Gee]

My answer to this question is difficult to answer as I have 4 greenhouses so I an practice rotation.

But thinking about it in terms of how other people go about I would say ring culture is the way to go particularly with tomatoes!

Tomatoes have a unique root system in so far as the top roots are feeding roots and the lower roots are water seeking roots. So if you plant them in a pot/ ring you can use a fresh compost in the ring/ pot and the water roots can seek their moisture in the existing soil below.

This way you only have to change the soil in the pot /  ring !

Otherwise  if you want to grow in the greenhouse border then the answer is change annually.

[pumkinlover]

I do as Teegee says and for the reason you are asking Robert. It is not just the physical work but the difficulty of doing it in a confined space with out breaking the glass.

[galina]

I partially replace when I have good compost available, but I mostly mulch with really nice compost.  Greenhouses here are in use all year round.  Yes mostly solanum in summer, but at this time of year it is salad stuff, brassica etc.  I also grow carrots, beans and squash occasionally.  It is not quite the monoculture that many greenhouses are.

At the moment I have one greenhouse without winter crops.  Candidate for a better effort at soil replacement.  But in practice that will only mean the top 4 inches or similar, not down to a foot.  If I had problems, I would consider replacing more soil.  Yes Pumpkinlover I also find it difficult to get a fork going in the greenhouse, need to be very careful indeed.  A modified method when the tomatoes need to be planted into slightly tired soil is to make really deep and wide planting holes and refill with a bucket full of decent compost or soil rather than with the dug soil 

[ACE]

I've been told the soil gets poisoned somehow, and has to be changed, but maybe I got it wrong. Blight wouldn't affect the soil, as the fungus is in the tissue itself.

I have never heard of poisoned soil before just by leaving it, perhaps the feed we put in turns it poisonous over a few years, although the blight is only in the tissue, you would have to be very good gardener to remove every tiny little bit. I rotate my outdoor toms, but still dose the strip with Jeyes before I dig it over for the next crop, just in case. But it is the same soil in those beds year after year. Perhaps indoors with its artificial climate and feeding regime it too intense for continual use.

[Robert_Brenchley]

I'm wondering whether it's a case of toms producing some substance which inhibits root growth. I can't find anything specific though.

[Tee Gee]

So far as I know because you do a lot of high potash feeds to ripen the fruit any surplus salts remain in the soil plus the tomato plants deplete the soil of many other trace elements.

The only way of finding out what is left and what is is depleted requires a soil test to determine what treatment the soil needs to get back in fettle.

The easiest way of doing this is to  'change the soil'

You could take the chance and plant in the same spot again and you might get lucky, then you might not, by which time it is too late to do anything about it!

As I see it; if there are high levels of potash left in the soil this is not a good thing for young plants as they need other minerals e.g. nitrogen & magnesium.

As you all know you not do not apply potash to tomato plants until after the first trust has set, but if it is already there you have the possibility of the plants contracting possibly a physiological problem from which they may or may not recover.

I am no expert on the subject but I guess the reason the common advice to change the soil is the cowards way out to cater for any of the unknowns I have mentioned catching you out the following season.

But as I said;...I am no expert, this is just my point of view!

[saddad]

I do the ring thing, with florists or other buckets with the base cut out... I also grow on alternate sides of the greenhouse/poly beds each year. It has worked well for the last 20+ years.

[Robert_Brenchley]

If you're right about the potash, then growing them to a decent size in a large pot before planting out might get round it. Worth trying anyway.

[galina]

Just a slightly off the wall idea.  Top the soil in your troughs with straw bales and grow the tomatoes in the conditioned bales.  They will rot down but should give you two seasons of good tomatoes.  Silverleaf is very experienced and successful at strawbale gardening.   

[galina]

just watching Charles Dowding on youtube.  His uses a no-dig system.  And every year he adds 3 inches of compost to his intensive polytunnel and that is it - no fertiliser added and he does close spacing and intensive cropping.  Sounds good and easier than digging soil out and replacing.  I realise that 3 inches is actually quite a lot of compost, but that has worked for him for years. 

https://www.youtube.com/watch?v=QVY4SJt4mzg

[Robert_Brenchley]

Thanks. That gives me an idea how to space the plants

[Vinlander]

The big advantage of a no dig method in my polytunnel would be that I'd not need the extra 3in/75mm of plank in front of the bed to stop soil escaping during digging... the 3in of compost would mostly stay put - even if the bed was already full before it went on (worms use very small shovels).

Unfortunately it becomes essential to maintain a "cordon sanitaire" around the PT to stop couch and bindweed getting in, but I'm working on that anyway - though most people already have that from burying a metre of the cover in a big U.

I have one big problem with 75mm of compost - it's a lot over 15m² - that's over 1.5m³. It would take every scrap of compost from both the plot and my back garden to get near it. And I'm not prepared to give up using the roughest, dirtiest tussocks in my "anti-fly" builders bags.

Maybe I should start a rumour about why my site doesn't take the free compost offered by the borough - other plots take it and get well over a m³ per person twice a year. There are some counter rumours about 'pyralids but in reality it's a lot safer than any manure in that respect - unless you actually know the cows/horses owners on a regular eye-to-eye basis or better.

Cheers.

[BarriedaleNick]

Tomatoes have a unique root system in so far as the top roots are feeding roots and the lower roots are water seeking roots.

Do you have any references for this?
Don't all roots absorb moisture and whatever nutrients that moisture contains so, for example, if the top roots are in dry soil they are not going to absorb water and therefore nutrients as well..

I have been reading through this http://soilandhealth.org/wp-content/uploads/01aglibrary/010137veg.roots/010137ch26.html
Which is really interesting on how roots can get damaged by transplanting...

[InfraDig]

A really interesting link, thanks very much. A lot to think about! And loads of pointers to where I'm going wrong!!

[sunloving]

I would normally just manure at the end of the year and use the same bed again.
However since I'm getting used to my new poly and the tom bed last year was so blighted I'm moving the toms to the middle bed for hopefully better air circulation.
Can't wait now for the seed sowing bells of February to get a fix of young shoots appearing!
X sunloving

[sparrow]

I was told to top up each year and change the soil to 1 spit down in the greenhouse every 3 years when I asked at the RHS. Reasons were to avoid a build-up of bugs & viruses.