Plant them, then put the cardboard down around them.

Forget soil amendments unless you are planning on doing a large bed.

i would pot the into one gal ... and plant them in fall.. when the nights start cooling ...

there is no rule..that just because you buy it.. that that is the proper planting time ...

see link ... no amendments..

if you wait for fall.. kill the spot for the plants... nto the whole bed.. just a 3 foot spot for the plants ....

or plant now.. and do as mad suggests ...

i would not hold over winter.. anything in a 3.5 inch pot ...

ken

Here is a link that might be useful: link

Rule of thumb is that anything you hope to winter over in a container needs to be hardy to two zones colder than you. For Buddleia/butterfly bush & Weigela, that would be Z4. Weigela is hardy to Z4; butterfly bush is generally expected to be hardy to Z5.

I'll back up Ken & mad_gallica and suggest planting them in the ground so their roots can get established before winter. Holding them in pots isn't ideal, especially for young, small plants with immature root systems.

Thanks for the advice, everyone. Fall planting it is.

While I hold them in gallon pots over the summer, should I use my garden soil or a container mix?

Ken, very interesting link, especially the part about not adding extra amendments. Definitely the opposite of what I do when I plant perennials.

Holding them over the summer in potting mix should be fine. It's likely too light/thin for holding them over winter unless the pots are sheltered and up against the house foundation.

Thanks gardenweed!

Those little guys are getting a new (temporary) home this weekend.

If you are going to keep them in pots over the summer, remember you have to water them. Plants in the ground don't necessarily need to be watered. Plants in pots do.

I would stick them in the ground - anywhere. Anywhere is going to be better than pots for the summer and winter and a lot less work. You can always move them next spring.

Kevin

I have overwintered shrubs including seedlings of buddleia in 4 inch pots and larger by sinking the pot in the ground and mulching well. Since it is spring/summer you can expect growth so potting up is a good idea if you decide to wait until fall to plant in the ground. I keep pots on my back patio or sink them in the ground for the summer. Those in the ground need less attention and are still easy to pull out to plant when I find them a spot or the weather is right. Sometimes they spend more than one year in that holding area still in the pot. Maybe that holds them back but they grow well once planted in the ground.

Bluestone shrubs are quite small, and though they may need to be put in larger pots, they certainly don't need gallon pots if you do decide to hold them in pots until fall.

The larger the pot, the less faffing (watering)....and the ground is the largest pot of all. Puddle them in really well, water weekly, no worries. Put some marker sticks around so they don't get trod on (or does that just happen in my garden?)

Capanula, what you're saying makes sense, so a gallon pot it is.

The only time I tend to stomp on plants is when I'm working on one and don't place my feet carefully enough so the plant behind me gets attacked. Fortunately, I have small feet!

I ordered some shrubs from Bluestone lasts year. Yes, they were small, but a couple of months after I planted them I decided to move one of them. You should have seen that root system! It would have easily filled a gallon pot even though the plant hadn't appeared to grow that much.

As as been said many times, the first year in the ground, a shrub spends its time expanding its root system. There may not be much top growth, but that doesn't mean it isn't doing anything.

Kevin

Kevin, that's great to hear. I know a lot of people are unhappy with the changes made by Bluestone in that last couple of years, but I find their plants to still be exceptionally healthy.