The spray is called a desiccant, and while it be a great help, it doesn't guarantee survival. Mulch is an excellent idea, and most perennials will like it [just be sure to pull it away from the crowns next spring].

Plant zones are based on averages (highs, lows, dates, etc.) and of course can catch us by surprise when a winter turns out to be much colder or longer or drier or whatever. Technically, a plant that is happy in z5, [and is established in its preferred soil, moisture, drainage, and light] *should* have survived the average winter and will usually survive some extremes. You've named a lot of sturdy plants, mostly with good reps for non-fussy growing, so I'm wondering if they were babies? did your locale have a unusual winter (too dry, too wet, and/or extreme/unusual cold)? were all their basic needs met - a plant that wants good drainage is not going to do well if we plop it into clay and winter can be the final stressor.

I live in your zone, down SE of Buffalo ... I try to buy and plant bushes and trees in the Spring ... if I plant trees in the Fall, they are dormant and I get them delivered mid-November.

I protect my bushes every fall by wrapping with burlap, and chicken wire, more to protect from deer and varmits than anything else.

If you are planting everything this late, it might be that your bushes are not able to establish before the winter freeze hits.

I also mulch everything well every year ...

Hi Lana
One of the biggest killers in winter is plants going into it without plenty of water. Around here, October & November are NOT rainy months nor do we get regular snow cover. I need to keep my gardens watered until the ground freezes or I will lose plants to winter kill. Yes, some of my neighbors think I strange when I'm out watering perennials in a jacket but what do I care what they think! Ha Ha, my plants come back. Going into winter with very dry soil/roots is particularly bad if your plants are newly planted.

Just my 2 cents about your problem. Good luck and happy growing!

I also think that planting this late is not giving your bushes enough time to establish.
I don't know the particulars of your climate but Nurmey makes a good point. I also water during the (dry) fall and into winter. I water if less than 1" of precip for a few weeks and the ground is not frozen (which happens very late here).
The spray is an anti-dessicant and coats the leaves to keep the moisture in. I don't use it and prefer to plant with plenty of time to establish in the fall (or completely dormant), and water properly.

Thanks for the suggestions!
I'll get the anti-desiccant to spray the broad-leaved evergreens and try to keep the plants adequately watered right up until the ground freezes. I'll also use burlap shields for a couple of bushes and rise the acidity of the soil for my struggling Holly. Unfortunately one of the spots I planted my new Euonymus Fortunei Canadale is right in front of the house, by the entrance, so I can't cover the plant with burlap. The spot has northern exposure and is very windy, but I need it to be an evergreen, so it will look nice and green year round. This is the very spot I planted last year the Red Head Pieris and lost it to winter so I am not sure at all this one will survive...

dry winter winter winds are deadly to all plants. If you want to save that euonymus, I would NOT plant it by the front door this fall. put it in a wind protected spot and replant it next spring. You could put it in the ground pot, stem and all, search the library books as in protecting a climbing rose, and then plant it in its designed place next spring and keep it well watered. my SIL lives in town nearby and can grow zone 6 plants and has about 3 weeks more growing time, spring and summer. I am in the open country (near Ann Arbor MI) and have to be carfeful growing even zone 5 plants. I also lost a Pieris last year even though it got alot of water, my yellow sambucus is not happy even after 4 years in the ground, the blue girl holly finally gave up the ghost after 3 years of decline in a protected area too, roses forget them, the smoke trees do fine though. join a garden club and ask lots of questions, and get library books over the winter and read them all. good luck and have fun