This year we potted up a bunch of Potentilla but I stuck about 10 of them in a landscape planting to use as stock plants. The plants in the pots are far out growing the ones that I planted in the bed. Why? Potting soil must be pretty close to what it should be and the plants in the bed are small and mulched with 3″ of bark mulch. Not enough roots into the soil? Have we kept the plants in the pots watered more consistently than the ones in the bed? Probably.
I don’t know for sure, but as soon as I draw a conclusion about something I see something that makes me contradict my earlier claim.
So here’s my conclusion as of today.
In most cases if the soil in your yard is good plants in beds will out grow plants in pots. Unless your potting soil is near perfect.
Plants in pots need a lot more water. A lot more water!
Plants in pots are much easier to care for and keep weed free because you can pack them together then spread apart as needed. Once the plants fill out the pot the weeds don’t have much room to grow.
Plants in the ground? It takes a lot of calories (energy) to get plants out of the ground and the window of time to do so is pretty small. Digging season starts after Thanksgiving and ends about mid April in zones 5 and 6. Other zones are similar but the window is longer in the far north and shorter in the south.
If you plant in the ground, mulch the beds. This spring we put a lot of time, energy, effort and money into mulching all of our Japanese maple beds. What a difference. Weeds starting showing up in the isles weeks before the mulched beds and we used a pre-emergent herbicide over the entire area. The mulch helped the plants, it really helped with weed control, and I believe it carried the pre-emergent better than the soil.
Plants in the ground or in the field have to be close enough together to make weed control manageable, and even then, you’ll spend a lot of time “managing those weeds”.