I had a recent soil test done on one section of my garden. I have had plants die in the past and recently the plants looked poorly in most of the area.
The test showed high levels of phosphorous, potassium and organic matter. The test does not test for nitrogen, but based upon my organic matter levels they didn’t recommend any added nitrogen. They did mention that, “Nitrogen is not listed because the level is not stable in the soil. It changes too frequently.”
What they recommended was to cut back on the compost, since my organic matter level is so high and to cut back on the phosphorous and potassium. He said that high levels can stop the uptake of other nutrients.
Their main recommendations were…
Just use a high nitrogen fertilizer without added phosphorous or potassium – blood meal, cottonseed meal etc.
Don’t add compost for a while. Try hardwood mulch on top
I did notice that added milorganite did green up the plants, but also adds phosphorous.
I noticed that Home Depot is carrying a number of Kellogg brand soil mixes, so I decided to buy all three and see what the difference is between them.
Raised Bed and Potting Mix – $8.27/2cu.ft. – This mix had 2.5 cups of large wood particles out of 12 cups. Other than that, it is similar to #3 – the Premium Potting Mix.
Garden Soil – This is not Top Soil. At $6.97, it is the cheapest, but is more like a nice mulch, not a soil for planting. it has 4 cups of large wood chips out of 12 cups. It does not contain perlite.
Potting Mix – Premium Mix for Outdoor Containers. This seems like a nice mix for use in a pot or in the garden. Out of 12 cups, it only had 1 cup of large wood chips and perlite. This is my favorite and at $6.47/1.5 cu.Ft., it seems like a good buy.
All three contain tiny amounts of fertilizer, so you will have to add your own fertilizer to these mixes.
Kellogg – All Natural Topper – a new product I just discovered. Unfortunately it contains 4 cups of large particles out of 12 cups. $6.27/1.5 cu. ft.
Here is another brand from Miracle Grow – Natures Care – organic raised bed soil. Unfortunately, it is about 40% wood particles. It would make a nice mulch. It has a little nutrition, but not much. It also doesn’t have perlite.
After watching a couple of years of Monty Don on “Gardeners’ World,” one of the differences I noticed was he doesn’t use peat moss in the U.K. He mainly uses a lot of compost, perlite and grit. I’ve also never seen him use fertilizer other than compost which he makes himself.
You would be hard pressed to find this mixture in any nursery or big box store.
What I have found is a mix which seems similar to what Monty Don uses.
SLC Grower’s Mix has a combination of pine bark fines, compost and PBH rice hulls, although they wouldn’t tell me the exact percentages.
When I talked to SLC they did indicate that they would recommend using Osmocote if I was planning to grow from small size to large size in a pot. He recommended using a medium dosage. They do include a small starter nutrition in the mix and a micro-nutrient charge.
The product will be a bit drier since it drains so well. You may have to water more often.
I’m going to be doing some tests with this product versus my standard BX ProMix. The SLC mix is only $6 per 2 cu. ft. bag.
You would obviously be better off buying the mix in bulk, if you have a place to dump it.
The one odd thing about this mix is that it is in bags which say Cotton Blossom Compost.
I tested various proportions of vermiculite for starting seeds.
1. 100% vermiculite
2. 100% Miracle Gro potting mix
3. 50% vermiculite and 50% potting mix.
4. Potting mix on the bottom and vermiculite covering the seeds on the top.
Here are the results below from best to worst – I had 18 hollyhock seeds per tray.
100% Vermiculite – 8 seeds germinate
Miracle Gro covered with Vermiculite – 7 seeds
50% MG + 50% Ver – 4 seeds
100% MG – 1 seed
Vermiculite has zero nutrients so I will be bottom watering with Jacks classic 20-20-20 with micro-nutrients. This variety is more expensive than Miracle Gro, but does a good job. Note – see my results below – this does NOT work!
Note – wear a mask when handling dry vermiculite. Wet the vermiculite as soon as possible to reduce dust particles and possible asbestos.
As you can see in the picture above, while vermiculite is great for starting seeds, since it has no nutrients, the seedlings don’t mature and grow very well. Even though I have constant bottom watering with Jacks water soluble fertilizer. The seeds in the picture are dianthus and basil. They are much healthier in the Miralcle Gro mix.