The BladeForums.com 2024 Traditional Knife is ready to order! See this thread for details:
https://www.bladeforums.com/threads/bladeforums-2024-traditional-knife.2003187/
Price is $300 $250 ea (shipped within CONUS). If you live outside the US, I will contact you after your order for extra shipping charges.
Order here: https://www.bladeforums.com/help/2024-traditional/ - Order as many as you like, we have plenty.
I garden with my BM 810 Contego. The big flat blade is awesome for digging in soil.
I would personally use a shovel but if you want a knife then go with a Ka-Bar heavy warthog. It has a wide blade and the overall shape is very 'shovel-like'. It also has a softer steel helping it resist chipping and overall edge damage. Since you suggested that it would have multiple blades. Most knives that fall under this category are slipjoints and those are too beautiful to use in that role. Additionally, the blade is too small to be effective at diging. I mean if i came down to it, then really any knife could do it.
I use an Ontario SP8 for this kind of work.