SIP potting mixes

[71GTO]

I had some conversations last year on this, but I'm going over it again since I'm thinking with my new house I want to you the SIPs for the deck so they don't rot the wood under the pot with water draining if that makes sense... I have three Bills figs sips and I used the mix he sells when I tried then a few years ago, but it is to heavy. I have had some conversations with other member in the past and they have used promix with good results, but after last year I really like Farfard 52. What mixes have use used in your sips that are lighter?

[F. Bennett]

For my SIPs, I use Pro-Mix BX with mycorrhizae. I got it at a good price, otherwise I probably would've chosen Pro-Mix HP due to more perlite. I did add extra perlite to my mix though. I had great results last year and I am using it again this year again.

[71GTO]

Yeah, I have used those in he past. I was adding perlite pine bark and running all over to find ingredients. Last year I tried Farfard 52 and it was very close to the mix I was making and it was less work to get it. It was more money, but I dont have the time and space to keep all the supplies. Farfard 52 is peat based also, so it should work of promix works.

[Rafaelissimmo]

Fafard 52 is what I use for pots, I would try to add some compost to a sip mix, it may be denser but it is harder to fertilize the sips, so I would want more nutrients in the mix than F 52 or promix can provide, maybe a blend of compost and F 52

[71GTO]

That is true. I followed bills set up and mixed in osmocote, but I always wondered how well it worked if the top of the mix never got wet since it was covered. I would occasionally water the pot from the top to try to get it going also occasional MG from the top.

[F. Bennett]

I had mixed osmocote with my covered SIPs. I don't know if I get enough moisture at the top level to activate the fertilizer, but I will keep doing this since I had good overall results.

[Rewton]

I got these mixes from ascpete and they have worked well for me:

Mini-SIPs: 2-2-1 (coir-peat-perlite) where the coir volume is measured after wetting it. For every 5 gallons of mix add 1 cup of dolomitic (agricultural lime). Once roots appear dilute liquid fertilizer is mixed into the water.

Larger SIPs: 2-1-1-1-0.5 of pine bark fines/coir/peat/perlite/oil dry. Per 5 gallons of mix also add 1 cup dolomite lime,1 cup espoma tree-tone (or garden-tone) and 0.5 cup espoma iron-tone.

[Coop]

I have 4 of Bill's Figs pots and I use the 100% mushroom compost that he gives you when you buy it. It seemed like an a heavy mix (and it is) but I can't argue with the incredible success of these SIP's . Now when I root prune I still buy and use 100% mushroom compost. It's a very heavy pot to move into my shed but the results are phenomenal.

[71GTO]

Yes, I used mushroom compost when i had them set up, but I think its just to heavy. I'm Thinking I would like to keep these on my deck and I don't want to kill myself getting them up the steps. Thanks Rewton, I might start making my own mix some day, but two years ago I was driving all over the state looking for the right ingredients, buying as much as a can and storing it in my every shrinking garage, then spent a lot of time mixing everything up just right making a mess. Then last year I tried some of the bagged stuff that was recommended on the forums and i think I had good results. i really didn't see much of a difference from the 5-1-1 type mix I was making and I just opened the bag up and filled the pot. The plane to buy it is 15 minutes away and it was nice to not spend all day just up potting.

[Rewton]

If I could find one of the high quality mixes close by for a reasonable price (like Fafard 52) I would be really tempted to go that route.

[71GTO]

I havnt done the math. In sure mixing my own was cheaper, but when I factored in two seasons ago I literally drove around all day trying to find this place that sold pine bark fines it wasn't worth it. On top of that the garage in my new house is smaller. I don't have space to store all these bags and bales. I'm pretty lucky there is a nice nursery supply place near me. They have pretty much everything. The only downside is it really is geared for bulk. I don't buy enough at a time to get better prices.

[Rafaelissimmo]

Steve

Griffin greenhouse carries Fafard 52, my local hydroponic shop orders a large bag for me for $25. It is cheaper if you go directly to Griffin Greenhouse, but for me it is a very long way (near Trenton, NJ). Not worth my time to get the discount.

[71GTO]

Rafael, that is where I go. I'm right outside of Trenton. Griffin is a cool place for all kinds of stuff.

[Rafaelissimmo]

Ahh I envy you!

[eboone]

Question regarding potting mix for SIPs

From what I have read, the advantage of the 5:1:1:1 mix is that it promotes better drainage, preventing waterlogged soil and better air to the roots. In a SIP, many cover the top to reduce the effect of rain and water only from below. I guess this kind of mix would still help with aeration of the roots, probably compacting less over time, but I'm not sure how 'drainage' is important without water from above. Is this kind of mix (or 4:2:1:1 as AscPete has suggested in a similar recent post about potting mixes) better in a SIP simply because it holds less water than a standard Pro-Mix or MG potting mix?

[AscPete]

Ed,

Yes, I've posted this link before, http://ohioline.osu.edu/hyg-fact/1000/1251.html it has some useful information about aeration and water retention.

The finer mix will increase the saturation zone in the container. The more aerated coarser mix will decrease the saturation zone, which will also increase aeration. Drainage is important because figs like most plants don't like to grow in saturated soil, as the soil becomes more water retentive it will also be less aerated which will affect the plant's growth, but they can and will become acclimated to the increased moisture in time.
The inherent design of a SIP is based on the saturation zone, capillary action and the wick create this "zone" between the reservoir and the bottom of the planter.


BTW here's a list of all the commercially available mixes that have been used in Earthbox SIPs, http://earthbox.com/approved-for-earthbox

The SIP mix can be as simple as Peat (85% - 60%) and Perlite (15% - 40%) with the added amendments (pulverized Dolemite Limestone) and fertilizers, the higher peat content will just hold more water.

[eboone]

Thanks for your great insight Pete.
In your recent post in the "What potting mix are you using..." thread ( http://www.ourfigs.com/forum/figs-ho...sing-this-year ), you stated:

For containers, I'm still using Tapla's modified 5-1-1-1 mix, (Pine bark fines - Peat - Perlite - Calcined clay). the mix is still viable after 3 years in use. Dolemite Limestone @ 1 cup, Espoma-Tone Fertilizer @ 2 cups and Ironite @ 1/2 cup per each 5 gallon of mix. For SIPs I'm using the same ingredients at a ratio of 4-2-1-1. I often substitute pea gravel for the Perlite because it only adds ~ 6 Lbs for every 5 gallons of mix. And an added benefit of the Calcined clay is that it prevents the mix from becoming hydrophobic and makes it very easy to water from a completely dry state.

If you are using a 4-2-1-1 mix, does that have enough peat to wick? Above in this thread you said that a SIP needs >60% peat to wick? I'm just trying to make sure I do not screw up 30-40 5g SIPs that I am making.
Thanks again for your help!

[AscPete]

You're welcome...

The "Peat" refers to high soil porosity content of the potting mix (fines). The Calcined clay also has high porosity, it absorbs water, so does Pine Bark and ~20% of the Pine bark fines when sifted will be smaller than 1/8 inch.
I prefer a more aerated mix, so I've settled on that ratio for healthier root growth. It would be easy to increase the actual Peat portion by 1 part to get better wicking / capillary action in the mix.

The general recommendation for SIPs is the one recommended by Earthbox, for regular Gardening of Vegetables and Flowers.

The growing media should be peat-based (70%-80%)

That's why the commercial mixes have been successful in use. You can simply test your mix ratio and or copy a commercial mix ratio that has been successful for SIP fig culture.

BTW Fafard 52 uses ~60% pine bark in its recipe, but its composted bark which increases the porosity (fines).

To put it simply, you have to consider all the properties of all the ingredients in the potting mix.