Adding compost every year to MM

If I keep topping off my boxes with compost every year and not mixing it in doesn't that change the ratios in the MM?
Or should I mix it in and add more Vermiculite and Peat Moss?

Thanks
Jeff

Mel's mix is the starting mix and will never again be like it was before you had your first planting. It gets better every year when you add the compost. It's the compost that will feed your plans.

I add compost to the bed and mix it in for the best results.

Thanks camp.... I was wondering about that mixing in part!

I read somewhere that the MM lasts for about 10 years. That includes adding new compost through out the seasons.

What is supposed to happen at the end of the 10 years? Do we add some vermiculite and peat moss to the squares? I seems to me, a Newbie, that the medium would get heavier as the years go by and that adding a little vermiculite and peat moss every decade or so would keep it fluffier.

Comments?

in the old book and in the videos he wold mix up a square when he harvested and planted.

malefacter wrote:in the old book and in the videos he wold mix up a square when he harvested and planted.

Yup, but we go by the 2006 All New Square Foot Gardening and he says to mix in at least a trowel full of compost to each square after harvest.

I usually add a wheelbarrow full for a whole 4x4 box and mix it in. I get great results.

I know the official line is there for a good reason, and is likely the overall best guideline for the most people for the greatest amount of time.

Mel does note that vermiculite can break down, so mix it carefully. That's one reason to mix it by plopping it onto a tarp with other components and raising the sides until everything's mixed, rather than using a shovel to mix it in wheelbarrows or buckets or right in the planters, as I recall.

The breakdown (and lessening percentage) of vermiculite, and vermiculite in sizeable chunks, might not mean much to most people, but if I were in a particularly hot, dry, or windy climate, I'd probably give thought to adding some more vermiculite before the ten years is up. Just a personal opinion and not meant to sound any different. But it seems logical that in areas that stress plants for water more, vermiculite and vermiculite in larger pieces rather than degraded down too far, would be more important than it would in other areas with plenty of precipitation, moderate sun, or not-too-windy conditions.

The Mel's mix is designed for a starting point and does not need to be the same. Maybe when a gardener rehabs a bed after the sides rot, say 5-10 years old, then it may be of value to make a new MM. But the reality is the garden plants will thrive better in a older, well composted, fertile growing medium of organic tilth.

From what I've learnt here on site and other places the MM will eventually lose it's fantastic drainage & air entraining capabilities as the vermiculite breaks down into clay type particles that are barely visible to the human eye ,the decaying peat will add to this by binding to the microscopic particles  forming a " new mother earth "type material .
 
The 30yr old leaf mould in the lower parts of my 900 mm ( 36 inch deep ANSFG beds  is strange .. It is like a dry crumbly paste when slightly moist.
When wet it holds a lot of water so is heavy to work even with liberal amounts of vermiculite in it.

It drains well but not as well as MM ,  plant roots can penetrate it but in the thousand tonne rows where my leaf mould came from very little had penetrated much deeper than 500 mm ( 18 inches)  The lower levels of the 3 mtr /10 foot high rows was quite compacted and very dense after being tracked in by a bulldozer , it was a bit like a chocolate bar  kept in a fridge .

 If you rub it between your fingers it leaves you hands in a strange state , there is no sand /grit in it .. your skin soon dries out and becomes quite rough.