Growing Experiment With Malibu Compost

Malibu compost is one of the most expensive products I’ve ever purchased. It runs me about $35 per cubic foot bag where I can get it.

The compost is definitely superior to other bagged compost products on the market. It has the smell of forest soil and it rarely has wood chunks or pieces in it. (It does occasionally but I can easily take them out.)

The compost also has amazing aggregration, which shows me the biological activity is high.

I can also be assured that it isn’t going to give my crops problems like other manure-based composts can because it has a biodynamic certification. This tells me I probably won’t run into any aminopyralid issues.

So a little backstory here…

I’ve used Peaceful Valley’s organic compost for some time at the school I work at mainly because it was the only plant-based compost I could find. I don’t like the idea of using manure-based composts that are derived from CAFO’s because it’s inhumane and I don’t want to support the industry.

The compost is okay. I definitely had to amend it with fertilizer to bring the nutrient levels up. I couldn’t rely solely on the compost to supply everything the plants needed.

This has looked different over the years on how I amend the compost. I used to amend with other plant-based options like alfalfa meal, neem meal and soybean meal.

Over time, I started using synthetic fertilizers to boost the compost. That worked really well.

I still believed though that I could find a compost that would give my crops everything they needed. That’s what the experts say, right? Compost has everything a plant needs.

Low and behold, I finally made the investment in Malibu compost. The price was really one of the things holding me back from purchasing it.

Going from Peaceful Valley’s $7-per-bag to Malibu’s $35-per-bag was a huge jump, so I really needed it to work to justify the extra cost.

I can’t remember where I’ve heard this but I’ve heard that good compost should be brown in color, not black. I don’t know why we think black soil is the ideal or where that idea comes from. I will say that the terra preta soil in the Amazon is black and nutritious, but that’s because of the high charcoal content, not necessarily because of any other reason.

So Malibu compost is a nice chocolate brown whereas Peaceful Valley compost is dark black. I believe Peaceful Valley’s compost has high ash content but also it’s probably because it is not manure-based. Manure compost tends to be brown.

I right away tried to grow seedlings in pure Malibu compost. I’ve never had luck growing seedlings in Peaceful Valley’s compost. Everything usually sprouts nicely but then the young plants run out of nitrogen.

The seedlings in Malibu compost also all sprout nicely but then they also seem to run out of nitrogen. I even filled some fabric pots with 100% Malibu compost and ran into the same problems. The plants start great but then run out of juice.

Let me back up and say that I’m an experimental grower. I am fortunate to have a job where I can push the boundaries of horticulture and try and find new techniques and approaches that could help the field. One of the ways I experiment a lot is with trying to find out if plants, especially vegetables and other annuals, can truly grow in compost their entire lives.

I do these experiments because others have done this, too. Charles Dowding, Paul Kaiser, and other no-till growers grow in pretty much compost alone. I’ve tried their methods but haven’t experienced the same success. This is why I experiment: to find the ways that will work in my context.

So here is the latest experiment:

I’ve set up three different growing mediums to see which results in best seedling growth. I chose to grow Cornitos peppers.

The first growing medium is the control. This is 100% Malibu compost with no added amendments.

The second growing medium is 100% Malibu compost with slow-release fertilizer. I chose slow-release fertilizer so that I wouldn’t have any germination inhibition from the quick nitrogen release. The idea is that once the seed sprouts, it can get extra nutrition from the synthetics that the compost can’t deliver.

The third growing medium is 50% Malibu compost and 50% pumice with slow-release fertilizer. I wanted to see if another issue might be the density of compost alone causing anaerobic conditions. We know plant roots need oxygen so cutting the compost with pumice would potentially see if the compost itself is an issue.

My hypothesis is that the second growing medium is going to give the best growth because I really believe the nutrient lack is the issue. Elaine Ingham has stated before that compost can have great porosity, especially if well made, so I don’t think the compost is lacking airflow. Malibu compost has great aggregation and water usually flows really quickly through it, so I don’t think the oxygen issue is a real one.

I am growing the seedlings in the same container sizes and in the same location, so soil volume and light have been accounted for and shouldn’t be variables. I’m also giving each medium 1L of water per day to make sure that is controlled, too.

I’ll post an update once I get sprouts and I’ll also make sure to add some photos so you can follow along.

My plan going forward with this site and these posts is to learn in public and show my experience along the way. I’ve been a horticulturalist for a while now, but I’m always learning and I’m willing to share that journey with others.

Let me know if there’s an experiment you want me to try out. Like I said earlier, I have a lot of resources on hand and I can also use the experiments as teaching tools for my students.

Thanks for reading.