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Pot sizes & soil mixes

Posted by emorems0 PA - 6a (My Page) on
Sat, Feb 22, 14 at 0:16

I've read through a few posts about soil mixes, but I suppose I'm looking for something more specific on certain plant requirements...

I'm going to be potting several blueberries and raspberries this spring and I want to make sure I'm giving them the best start I can. I plan to keep them in a pot for the next year or two and then plant them in the ground after our next relocation.

I know blueberries need acidic soil, when I had picked up a couple blueberry plants a few years ago, the farmer told me to pot them in a mix of sand and peat moss (I forget the ratio off-hand, but it's what they used on their NJ blueberry farm). I'm wondering if I should do the same, or if there is a better soil mix to use.

I have no idea of the soil requirements for raspberries other than that they will surely need different soil than the blueberries.

I also pot a couple cherry tomato plants each summer because my in-ground bed won't hold all of the plants I want to grow. In the past, I've just used garden dirt/whatever I had lying around and they did okay, but I'd like to do better this year.

The cherry tomatoes will be in 6 to 8 gallon plastic pots. I haven't bought the pots for the blueberries and raspberries yet... are those cheap plastic nursery pots okay? What size for a young blueberry or raspberry?

Thanks for the help... I mostly do in-ground planting and have been dubbed 'black-thumb' by my husband for my ability to forget to water our indoor plants. I never really thought about treating container plants so differently from in-ground plants, so I'm looking here for advice to help my container plants produce this year.


Follow-Up Postings:

RE: Pot sizes & soil mixes

If you've already done some reading, you're probably familiar with tapla's 5-1-1 mix. That should work well (it has for me) for all three plants that you mentioned. The only change that you'll need to make is to leave out the lime when making the blueberries' mix. The purpose of the lime is to raise the pH of the mix (which is why it's a no-no for blueberries, who require an acidic media) and to provide a source of both calcium and magnesium. For the blueberries, you can replace the lime with gypsum (for calcium) and then mix a little bit of epsom salt (1/8 to 1/4 tsp per gallon once per week or so) into your irrigation water to provide magnesium. As for pot size, I've grown both blueberries and raspberries successfully in pots from 7 to 15 gallons. I don't see the need to go any bigger than 15 gallons, especially if they'll only be in the pots for a year or two. I'll conclude with a few pointers on growing blueberries in pots...
  • If at all possible, irrigate them exclusively with rain water. If you do need to use well or municipal water, which typically contains bicarbonates that will raise soil pH, you'll likely need to acidify it.
  • Blueberries do best with a fertilizer that provides nitrogen in the ammonium or urea forms (as opposed to nitrate). I like Jack's Acid Special, but you can also use Miracle-Gro or Mir-Acid.
  • Blueberries' root systems are very sensitive to drought, especially when they're first getting them established. Never let the soil
    get too dry.

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