Everything grown in a container with a soil-less mix will need fertilization. There is almost no nutrient load in container soils - the plants rely on you to provide what they require. It is very different from an inground planting where they can access whatever they need. I'd add a slow release fert when potting and then repeat at the start of each growing season until you get them in the ground.

depends were you are .. and what winter means ..

i would NEVER use time release in pots.. in MI ... unless i was sure it was the 3 month formula ...

you NEVER want plants hyper ferted going into fall .. growing lushly ... at this time of year.. they should be slowing down for winter dormancy ... or there is great odds ... they will die over winter ...

you could just as easily mix up a 25% solution of water sol fert ... and splash it in the pots in june and july ... and that should do just about all you need for the summer growing season ...

3 year project in fabric pots???

ken

Only slow release I've got in the stash is some Oscmocote but this is more for the indoor stuff I have around. Could pick up some Plant Tone I suppose.

Indeed. 3 yr fabric in fab. pots. I'd like to get a head start on these slow growers.

Got it. Not sure what the learning curve is with these fabric pots. Example, tomato plants in raised bed if not cheap #@! plastic pots, growing nice and thriving.

Same plants in container pots. Mixed both tomato tone and some oscmote into the fert mix. Puny puny growth except for maybe 2 pots. All in 15 gal. fabric pots each. Just started 3 ago and started doing a weak diluted liq. fert to see if it will boost up the growth.

Comparatively, in my cheap plastic pots with probably 5-7 year old potting soil, never amended, etc - the plants are 5-6X as big as the ones in the fabric pots.

Depending on where you live, the plants could freeze-dry in pots over the winter. You really need to say where you live for good advice.

Zone 7B. I asked about something similar in the container forum suggesting I could put the pots in the garage for the winter. Many suggested the boxwoods would be okay outside.

In zone 7b they will be fine outdoors in winter with NO protection. Just make sure they stay hydrated trough the cold weather.

I have a similar question, but haven't got any response in a thread I started. Hoping to get some insight here!

I recently got a green velvet boxwood in a pot. The container height is 13 inch. The sides of the square are 9 inch at the top and 7 inch at the bottom. (see photo attached). Can I keep it in its current pot? Ideally I like to maintain its current size but I'm worried that it's not going to survive in the winter. I live in zone 5 and the label on it this boxwood says it's hardy for zone 4. I live in an apt so will have to keep it in the balcony over winter.

Also, if. I repot the boxwood, what would be the recommended potting mix? OP suggested bark, potting mix, and perlite. What would be the recommended ratio?

I'm a newbie to gardening and I'm so afraid of killing my plants! Thanks for your advice!

No, that probably won't work. I'd put it in a larger pot since it looks like it's probably maxed out the root space in its current pot and the mix for nursery growing may not be ideal for long-term.

Usual general guideline is 2 zones hardier for things in pots, but I've had a difficult time with most things in pots overwintering here on the northern edge of zone 5. Try insulating the pot really well - surround it (including on the soil surface) with bags of something like densely packed foam packing peanuts and put it against a corner against the building to prevent the soil freezing solid or even worse, multiple freeze-thaw cycles. You could also surround the outside of the pot with sheet builder's foam if it surrounds all sides and the bottom with something on the surface to help reduce temperature swings. A larger pot will help mitigate the temperature swings, but no guarantees. Try it and report back how it goes.

Thank you! I will repot it in a larger container. Im not very clear on insulating it.. Do I put the packing peanuts in the container with the soil? Will it take up too much room for the roots? Im not sure what's a sheet builder foam, but I will look for it..

The "two zones hardier for potted plants" seems to be one of those horticultural myths that just will not die. Hardiness refers to a plant's genetically determined ability to withstand the average winter lows in a particular area if it is planted in the ground. The roots of plants in pots do not have the protection of the ground's thermal mass and can be badly damaged or killed if the roots experience temperatures in the teens and 20's. How hardy the plant is rated for in ground planting has nothing to do with this. Thus the need to protect potted plants by moving them into a garage, cellar, etc. for the winter, sinking them into the ground or providing some other form of insulation.