If you’re contemplating putting in a native seed flower bed in late fall, August is a good time to get the soil ready.
Your main job is to get rid of all the grass and weeds and have a clean area without any vegetation. Don’t till as that will bring up weed seeds.
I’d loosen up the top 1/2″ of soil and keep the area moist to encourage any weed seeds to germinate now before the growing season.
In St. Louis, Scott Woodbury our resident expert, suggests advice from Merv Wallace… “Merv recommends one ounce of seed mix per 400-500 square feet and 3 grams per 20 square feet. With your 4 grams, you are looking at around 25 sq ft.”
Sow the seeds on the surface in December.
I’d suggest mixing the seed with either play sand or potting mix. It makes for better disbursement when you throw the seeds out. Don’t mix into the soil or cover with straw. Just let the seeds sit on the surface. Winter frost heave will move the seeds into the upper layer of the soil to the perfect depth. Seeds will sprout in early April.
Native plants don’t need fertilizer, but might need watering during the first year.
Note – I like to cover my seeds with a light dusting of potting mix to hide them from the birds.
As I trimmed back some of my aggressive growers by about half, also called the Chelsea Chop, I decided to try leave my trimmings on the ground. I did cut them into four inch pieces. While this may not be appropriate for some more manicured gardens, in this pollinator garden, it makes sense.
I have read and seen this technique online from a couple of experts and it seems to work for a Chicago Botanical garden and a KC expert – Lenora Larson.
What I like about this technique is that it avoids fertilizing, composting and adding mulch.
While you may want the outside edge of your garden to have a more kept look with nice looking new mulch, the inside can be covered with cuttings which will decay and feed the soil.
While there are lots of options when it comes to starting seeds, here is the method that works well for me.
I start with BX ProMix. It can be hard to find, so be persistent. Sometimes Walmart and Menards have a similar version. The main thing is that it has Mycorrhizae fungi.
I put this in a wide covered container, 9″ x 14″ x 5″ = 630 cu. inches, just to make it easy to work with. If it is dried out, you may need to add water to make it better when planting. ProMix does not have any nutrients. Keep the lid on when you are done.
I then add Osmocote Plus to the mix – follow the directions on the container.
I finally add extra Mycorrhizae to the soil – 1 cup per full container.
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.