Tina is correct. To put a plant in stasis you need to place the plant in a container that is "locked down and secure". Locked down plants, even within a container will continue to do growth checks, and require care, this is true of plants in your backpack.
I used to have a little book I copied and gave to new gardeners. I had it all memorized, but it has been so long since I did serious UO gardening, I'd have to guess.
One thing I do remember in terms of tips for making your gardening life easier when you have a real life to attend to:
Place a container in easy reach of your plants containing half filled kegs of each potion type you need for care: Greater Heal, Greater Cure, Greater Strength, Greater Poison, as well as water pitchers. When you are ready to tend, simply place all the kegs in your pack with just 1 bottle, and you can dispense directly from the keg without the fuss of bottles of potions. I use half filled kegs because of the weight (my gardener was also an alchemist so I just filled the kegs to half again when necessary). I placed my plants in rows, stacked 3 high using small tables, with plenty of room between the rows. This let me keep track of a large number of plants in a small area, and check them without overlooking any tiers (if I got interrupted, I would lock down a keg next to the stack I was working on, so I could quickly return).
Place a water trough in easy reach of all of your growing stations, that way you can fill your pitcher from any location while tending your plants, without having to move.
Start your plants in batches in tiers ALL AT THE SAME TIME. You can then care for tiers and not have to worry about them following different growth cycles. That will allow you to tend them at the same time of day and keep them vibrant. The better you tend your plants, the fewer potions you use in their care, and the cheaper it is for you.
If you are planning to get serious about generations and cross pollination, I would suggest you start with seeds collected from boglings, as you will know they are first generation, and work your way through generations following the cross pollination tables on Tower of Roses. I stored my generation parents in chests (first, second, third, fourth and higher) in chests with colored backpacks inside, so I always had a particular type of a certain generation to cross whenever I wanted it.
You might notice that there tend to be more mutant plants in the resource plant bearing varieties for sale on your shard...that is probably because people grow those more in mass quantity, and it is easy to just keep crossing the highest generations, and thus more chance of producing a mutant.
-Skylark
