I'm looking for a variety of oleander that is cold tolerant (southern zone 7/North zone 8) that will grow 8-10 ft. tall
Calypso, Hardy Pink and Hardy Red are the most cold-tolerant varieties of Oleander however there are no guarantees that any particular variety will definitely grow to the height you're looking for. That said, fully mature Oleander shrubs can grow up to 12 feet tall with the proper placing and care.
These articles may help you:
https://www.gardeningknowhow.com/ornamental/shrubs/oleander/does-cold-affect-oleander.htm
https://www.gardeningknowhow.com/ornamental/shrubs/oleander/pruning-oleander-shrubs.htm
https://www.gardeningknowhow.com/ornamental/shrubs/oleander/oleander-growing-tips.htm
I have an oleander plant in my backyard that has white AND pink blossoms on it. Is this unusual or common?
Your Oleander is likely a grafted plant.
They are often sold with 2 colors and even tri-colored flowers on the plants.
Remember to keep children and pets away from a Oleander and use protective clothing when you work around the shrub. All parts of this plant are poisonous.
https://www.gardeningknowhow.com/ornamental/shrubs/oleander/oleander-growing-tips.htm
We have an oleander bush next to the driveway. It's about 4-5 years old and about 4 feet tall. The problem is that it's leaning out into the walkway. I put a metal cage around it last year but it has outgrown it and I can't find anything taller. How can I encougage it to grow up not out?
You can try attaching a stake and rope system to encourage a straighter growing pattern.
You would need to attach to the center most strongest trunk of the Oleander.
This combined with pruning should help you correct the growth pattern.
Take caution to use protective clothing and gloves when working with the Oleander as all parts of the plant are poisonous.
https://www.gardeningknowhow.com/ornamental/shrubs/oleander/pruning-oleander-shrubs.htm
https://www.gardeningknowhow.com/ornamental/trees/tgen/straighten-tree.htm
I have been given what was a standard Oleander, which is now a good 60 cm taller than it should be. My question is, how hard can I prune it? Not only is it too tall, it must have been close to a wall because most of its branches are on one side, which makes it difficult to keep it upright. I have repotted it.
Rejuvenating prunes should be done over a period of time instead of one big chopping session.
This link will help you.
https://www.gardeningknowhow.com/ornamental/shrubs/oleander/rejuvenating-overgrown-oleanders.htm
Olive tree covered with gall 'nodes.' Shrubs were trimmed back and are now covered with 'nodes' and very little leaves. Is there any cure?
You may need to dispose of the effected tree and plants if indeed they are infected with Crown Gall.
Here are links for you with more information.
https://www.gardeningknowhow.com/plant-problems/disease/how-to-fix-crown-gall.htm
https://www.gardeningknowhow.com/plant-problems/environmental/treating-leaf-gall-on-plants.htm
https://www.gardeningknowhow.com/edible/fruits/olive/olive-tree-care-information.htm
https://www.gardeningknowhow.com/ornamental/shrubs/oleander/oleander-growing-tips.htm
I have a garden in Southern Switzerland with three mature oleanders already planted. I want to infill with new plants to make a hedge. Can I plant now or should I wait until spring?
Fall is a good time to plant as well as spring. Make sure you water adequately to ensure the roots become established before winter.
Mulching the new plantings will help with moisture retention. 2 to 3 inches of hardwood mulch.
Here is a link with growing information.
https://www.gardeningknowhow.com/ornamental/shrubs/oleander/oleander-growing-tips.htm
I have 2 standard oleanders in pots. They had loads of buds but never flowered. Can you tell me why, please?
Oleanders have large root structures, so a large container with good drainage is necessary.
Plants can dry out easily in containers so you will need to pay close attention to watering. Daily water and even twice a day if the temperatures are above 85 degrees F.
Also check for pests and treat with Neem Oil if you see evidence.
These articles have more information on care of Oleanders.
https://www.gardeningknowhow.com/ornamental/shrubs/oleander/no-flowers-on-oleander.htm
https://www.gardeningknowhow.com/ornamental/shrubs/oleander/oleander-growing-tips.htm