The plant is on the conservatory windowsill, regularly watered & temperature of between 10-15 degrees. A clivia is suffering the same fate but not as greatly. Does the agapanthus need miracle grow?
The tips of this agapanthus turn yellow and then brown due to high temperatures.
Move to a cooler location and add some shade cloth to help prevent this issue.
Make sure you have air flow in your conservatory.
We moved into a house a year ago and let everything grow as it was so we could this Summer see what we have to work with. One mystery what is this ?
That is Agapanthus! Here is an article that will help:
https://www.gardeningknowhow.com/ornamental/bulbs/agapanthus/agapanthus-plant-care.htm
brought a cutting from my mother's 3 year old plant. Since putting it into our garden the leaves are turning yellow and some have gone brown. Is it save able?
It is common to, mistakenly, overwater plants as they are adjusting to their new home. This is likely the case, here.
It will be necessary to allow the soil to dry out down to about 2 inches between watering.
From here, I would recommend treating with a fungicide. Here is an article that will help:
https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
This article will help you to understand transplant shock:
This article should answer your questions about growing agapanthus from seed:
https://www.gardeningknowhow.com/ornamental/bulbs/agapanthus/propagating-agapanthus-seed.htm
Just inherited large clumps of lilies and think they are agapanthas. I can't plant right now. What do I do?
Since you are in zone 8b and experience below freezing weather, you can cut back the foliage, let the tubers dry for a few days, then store them in newspaper in a cool, dark place till spring.
Alternately, you can plant them in pots and keep them in the garage over winter. Just keep them in a frost free area that is light and dry and water about once a month.
https://www.gardeningknowhow.com/ornamental/bulbs/agapanthus/agapanthus-container-planting.htm
https://www.gardeningknowhow.com/ornamental/bulbs/agapanthus/cold-hardiness-of-agapanthus.htm
https://www.gardeningknowhow.com/ornamental/bulbs/agapanthus/agapanthus-plants-in-winter.htm
I have 2 garden beds edged by agapanthus, they were planted before I moved in so 10 yrs + and are a bit crowded now. This summer brown spots have appeared on the leaves, google says it’s likely fungal & to get rid of affected plants but that’s all of them ? is there a way to treat affected plants?
I don't think you need to get rid of them. Try spraying them with Neem oil. Here is more about their care and diseases.
https://www.gardeningknowhow.com/ornamental/bulbs/agapanthus/diseases-agapanthus-plants.htm
https://www.gardeningknowhow.com/ornamental/bulbs/agapanthus/agapanthus-plant-care.htm
Why does my plant never flower? Plenty green leaves
Typically, this will indicate that there is too much nitrogen in the soil, lacking phosphorus and potassium in the soil, or the pH could be out of range. Here are some articles that will help:
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-soil.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/soil-ph-plants.htm
https://www.gardeningknowhow.com/ornamental/bulbs/agapanthus/agapanthus-plant-care.htm