Thursday, December 12, 2013

What should I feed my Tomato pots?

Browallia Blue Bells. Click on this image to see a slide show of this week's Spec. Load.  

Hi Peter,  I have purchased some Scotsburn Sweet Bite & Grosse Lisse tomatoes seedlings which I have transplanted into a deeper tray but now they are ready to go into pots, but I need to know how deep the pots should to be and also what plant food to buy for  them,  I  have some  seaweed solution but would like to know a brand to buy to promote the fruit.
Looking forward to home-grown tomatoes.    Regards,    Lynne

(I promise I don't set these up.)  I wrote about soil preparation for Tomatoes only a few weeks ago, so you can review that information here.  Planting Tomatoes in pots is somewhat easier but the principal remains the same, the effort you are prepared to put into preparation will directly affect the results you achieve.

Start with potting mix.  Please be prepared to pay for quality "Premium" potting mix.  A pot is an unnatural environment for growing plants, good potting mix makes special allowance for this environment, garden soil does not.  Similarly cheap potting mix is a waste of money and only leads to frustration.  Experienced gardeners can play with cheap mixes, adapt the mix and get a good result but personally it's all just too hard. With the really cheap mixes that are un-reconstituted greenwaste, the basic material is so variable it is near impossible to create something useful. We use Debco potting mixes nearly exclusively and I am more than happy to recommend them.

That said, we make our own adaptations to the basic Terracotta & Tub mix.  This Spring we have been trialling additional Coir peat to help the mix hold more water.  If you're really keen, try adding 1 part moistened Coir to 9 parts Terracotta & Tub mix, I'll explain why shortly.  We also use more Controlled Release fertilizer than you will find in a bag of Terracotta & Tub mix.  You could safely add 60g of Osmocote or similar Controlled Release fertilizer (CRF) to a full 30l bag of Terracotta & Tub potting mix.  Try Osmocote plus Trace Elements Pots, Planters & Indoors, or Troforte M Roses, Azaleas & Camellias. These blends have more Potassium than most to help build strong cells and encourage flowers & fruit, don't get me started on the junk food that is usually dished up as fertilizer. I haven't trialled the Troforte products yet but I like the concept of adding microbes to the fertilizer to help protect against fungal disease problems.

So why add to the products I recommend?  The Debco retail potting mix products and very consistent but they are also conservative.  To ensure there will be no problems with over fertilizing, especially after mix has been left in a bag for 6 months and to ensure the mix will not become waterlogged Debco play it very safe.  There is plenty of room for a gardener to add fertilizer and as we have discovered, to enhance the potting mix's water holding capacity.  Both of these issues are important because a Sweet Bite or a Grosse Lisse Tomato will grow to 2m tall with many lateral branches.  That's a substantial plant that will need plenty of food and water.  Not only that it will mature and start setting fruit just as the weather gets really hot, so it's a substantial plant transpiring a lot of water and using a lot of energy producing fruit. I can't tell you how many Tomatoes we have lost at home because just as they start to look like something we get a burst of hot weather and fail to water them effectively for just one day.  One day is enough, it is near impossible to resurrect a mature Tomato that has been severely dehydrated.

Which leads to the final point.  Use a BIG pot.  Start at 400mm diameter, anything smaller will require at least twice daily watering on hot days. And watch the 400mm pots closely on a hot day too.  A few random thoughts: Water storing granules are thought to steal more moisture than they make available to plants; Liquid fertilizer once a week never went astray at recommended rates; alternatively top dressing pots as the plants mature with animal manure works very nicely too; think of Seaweed solution as multivitamins for plants, great to help the plant through the stress of transplanting, but it is not food.

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