Monday, March 2, 2009

Building a Strawberry Tower - Soilless Potting Mix

I am usually an organic gardener. However for this Strawberry Tower I could not use my normal gardening techniques.

The buckets that make up each layer of the Strawberry Tower are too small (about 3.5 gallons each) to maintain an organic ecosystem.

Instead of using potting soil, I am using a modifed version of Al's Container Mix.

I mix 3 parts Fir Bark - fine grade, 1 part Peat Moss, and 1 part Perlite. Fine Fir Bark decomposes slowly, Perlite is inorganic and peat moss is already decomposed organic matter, so this potting mix will last a long time (several years).

The most important characteristic of this potting mix is that it drains water very well. Strawberry plants do not want to sit in water, so having a well draining potting mix is essential.

I then sprinkle Dynamite Plant Food for Flowers and Vegetables. This is a Controlled Released Fertilizer (CRF) and suppose to last 9 months. I use a CRF because it releases nutrients slowly and will not burn the plants.

I throughly mix the ingredients together and pour the contents into the bucket (see picture to the right)

I leave about an inch between the top of potting mix and the top of the bucket, so that I can put in layer of Miracle Gro Moisture Control Potting Mix.

I find that the park-perlite-peat moss potting mix drains water too quickly. Water goes straight down without spreading to the rest of the mix.

I am using drip irrigation to water, so only a small area will get water.

I use the Miracle Gro Moisture Control Potting Mix to spread the water evenly across the Potting Mix. Water will not immediatly penetrate through the layer of Miracle Gro Moisture Control Potting Mix and will instead distribute itself throughout the Strawberry Tower layer.


  1. I have purchased a book called "Square Foot Gardening" & a strawberry tower after reading your blog. The book shows us the way to get the best soil by mixing equal volume of the vermuculite (coarse grade), peat Moss & compost. What do you think of this mixture? Do you think it will work for this strawberry tower? I will appreciate if you will comment on this. Tks


  2. The problem with vermuculite is that it compacts and loses its ability to hold air. Perlite is a better choice to keep the soil porous.

    Compost breaks down very quickly, so pretty quickly you end will end up with a mixture that is mostly vermuculite and peat.

    This is why I use Al's Container Mix.

    If you have a hard time finding fir bark, you can use redwood bark. Bark that is used for Orchids would work as well. The important thing is that it must be fine grade.

  3. Tks for your helpful information. Right now my tower is still unfilled since I had already planted my strawberry plants by using the raised bed method and Square Food Garden Mel's soil mixture. But I will try your soil mixture in the fall when I fill up my strawberry tower.

    I have lots of small, black, flying insects. I am not sure if they are aphids or not since this year is my first time doing food gardening. Those insects are not clinging onto the underside of leaves. I would describe them more accurately by saying they are around bottom half side of the plants, more closely to the soil level than top half side of the plants or above the leaves. I want to use soapy water to kill these insects. But I don't know how to aim at them, airimg into the air? In order to avoid any insects onto my strawberr plants, I even purchased the "row cover" to cover this 4'x4' bed. Can you tell me what is the insect name and how to get rid of them organically?
    Tks a million.

  4. I have not had a problem with pests or diseases in my Strawberry Tower.

    My biggest problem is squirrels that jump onto the tower and steal the Strawberries just before I am ready to pick them. I constructed a fence with bird netting around the lower part of the tower to prevent squirrels from jumping up. This weekend, I saw a squirrel climb onto the fruit tree that is next to the Strawberry Tower and jump from there onto the Tower to eat the Strawberries.

    Before I bought the Strawberry Tower, I looked at planting Strawberry plants in a Raised Bed. I decided against it after reading on the Internet all of the pests and diseases that Strawberry plants encounter when grown in the ground. That is why commercial Strawberry farmers use pesticides.

    The nice thing about growing Strawberries in the Tower is that I can control the growing environment. With Al's Container Mix and the physical separation between the Tower and the rest of the garden, there is no way for bugs or diseases to spread to the Strawberry plants.

    If you want to transplant the Strawberry plants from the Raised Bed onto the Tower, you need to be very careful that you do not bring along any bugs or diseases with you. I suggest letting the Strawberry plants sit in the garage or other dark space for a while before transplanting. This is what people do in the East Coast to keep the plants in the Winter.

  5. I just have to sit tight and play tough till this season is over. Hoping I will have some fruits to harvest for all my hard work. I will then start over again by buying new strawberry root stocks this fall and plant into my tower with new soil mixture. Hopefully this year will be a better year for me.

    Per your advice, I will also try to build a fence around this tower next summer.

    Tks for your time,


  6. Hi, I was so motivated by your blog that I started to grow strawberries. I bought the argotower last week and it should be arriving soon. I was wondering if you let your potting mixture sit for a while before adding the strawberry plants? Or would it be okay to transfer the plants right away?

  7. I recommend that you let the potting mix sit a while before adding the plants. The brand new mixture does not hold water well. That is why I had to add Miracle Gro Potting mix to the top so that it would be able to spread the water out better.

    However, after a week or so, the potting mix breaks down sufficiently that it will hold water better.

    The potting mix is good for a few years, so when it is time for me to replace the Strawberry plants, I will replace the potting mix and leave out the Miracle Gro.