Some thoughts... My experience comes from small-scale growing of Russian/German cultivars (Leikora, Orange
energy, one is supposedly Hergo) during the last 10 years or so. Clay soil, ph 4.5 - 5.5, continental climate, hardiness zone 6/7.
- Think about harvesting. Harvesting seaberry is hard. It's closer to pruning overgrown roses than it is to picking cherries. The berries do not dislodge easily and by the time you've applied
enough pressure to separate them from the plant, it's not unusual to notice that you've also squished them in the process. Maybe you want to chop of entire branches, freeze them and then shake off the berries. This works fine but, well, you took of a whole branch.
- While some cultivars have better taste than others, this is just not dessert fruit. Satisfaction is a combination of reality and expectation. In this case (and many others) it is the latter which will respond more easily.
- I've compared the taste of named cultivars that I had available with "no-name" seaberries which for some reason get planted as windbreaks at gas stations around here. There is some difference. Not night and day though.
- Soil pH is not so important. However, despite talk of this being a pioneer plant, soil humidity is quite important, at least until you have a 6 ft bush. Deep mulch helps but in the end there's no substitute for watering young plants. You can skip on it and they'll take much longer to grow up. If that's OK then... OK. (It's what I did as well. It took about 7 years to bushes to grow to a good size.)
- Once they have found their footing they will sucker. You may consider this good or bad. For a living
fence it sounds like a good thing. If you want your fence to get dense as soon as possible then 4 ft is not wrong. (It will get REALLY dense later on though.)
- In my book autumn olive named cultivars beat seaberry named cultivars in the resilience + N-fixing + taste combined category any time of the day. (Especially Sweet-n-tart which likes to bear fruit on the main branches so harvesting is super easy.)
Maybe some of this is helpful to you. Good luck in your adventure