Is this a disease or is my rosemary trying to grow roots from its branches?
These are Aerial Roots and they can be found on generally older Rosemary plants.
You do not have to do anything with them, they actually help the plant.
https://www.gardeningknowhow.com/houseplants/hpgen/aerial-root-information.htm
Is is possible to rejuvenate a Rosemary plant that has dried out and turned brown?
Unfortunately, no.
Rosemary can be finicky and die off quite quickly.
Here is a link to refresh you on the care requirements.
https://www.gardeningknowhow.com/edible/herbs/rosemary/grow-rosemary-indoors.htm
I have a 600mm x 380mm wooden planter on legs (see pictures), with 3m of black gardening cloth (to cover the inside of the box). I'm asking if this is feasible for growing Rosemary? The articles/videos on your website only showed Rosemary in a pot or in the ground. I'm wanting to grow Rosemary for use on food and cooking.
Thank you for your response, you suggest additional herbs would any of these work better? MINT, THYME, BASIL, ARUGULA (Rocket)
Though I would say it is possible to grow Rosemary in your planter, I would say it may be difficult.
Rosemary are very sensitive to watering. Too much or too little water and your plant will struggle and can die quite quickly.
This large of an area of soil may be difficult to control the moisture level.
You might be better off planting some additional Herbs for your culinary needs and growing the Rosemary in a pot.
Here are some articles to give you some ideas.
https://www.gardeningknowhow.com/edible/herbs/rosemary/rosemary-grown-in-containers.htm
https://www.gardeningknowhow.com/edible/herbs/hgen/growing-herbs-indoors.htm
https://www.gardeningknowhow.com/edible/herbs/parsley/growing-parsley-indoors.htm
I moved my outdoor rosemary inside last fall and it seemed to adjust ok. About 6 weeks ago it started getting really dry and several of its growing shoots fell off. Now it has only one shoot left, which has dried out, leaving nothing actively growing and soft on the plant. Is it a lost cause? Is there anything i can do to revive it?
You are not alone in issues with growing Rosemary plants indoors.
If the plant has died, it will not come back.
Try snapping the stems and if they break, they are no longer alive.
Here is an article that will help your review the care information.
https://www.gardeningknowhow.com/edible/herbs/rosemary/grow-rosemary-indoors.htm
1st of the year in early spring I planted a Rosemary herb (Rosmarinus officinalis). I noticed today it has an almost white fungus or some sort on the plant. Do I need to treat it or am I over watering the plant?
Your Rosemary has Powdery Mildew.
Here are some links that will help you with care and treatment.
https://www.gardeningknowhow.com/edible/herbs/rosemary/growing-rosemary-plants-rosemary-plant-care.htm
https://www.gardeningknowhow.com/edible/herbs/rosemary/white-powder-on-rosemary.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm
I'm based in George, South Africa (winter rainfall, semi subtropical climate). I've been struggling to get adequate growth on my propagated rosemary clippings, grown in containers. I've been researching, in vain, on how long it typically takes for clippings (approx. 3-5 inches each) to reach an acceptable size. My clippings root just fine and are very much alive, but I've seen only about 2-3 inches growth in the last 7 months. Is this normal? I know they are slow growers, but should it take this long?
Taking cuttings in spring when the plant is actively growing is the best time.
Using rooting hormone can help the process but it still can take a month or more to root the cuttings.
From their it can take several weeks or months to develop plants with good root structures.
Here is a link to refresh you on the growing requirements.
https://www.gardeningknowhow.com/edible/herbs/rosemary/how-to-propagate-a-rosemary-plant.htm
Just planted my rosemary and the tips are turning brown. Why?
This article will help you:
https://www.gardeningknowhow.com/edible/herbs/rosemary/brown-rosemary-plants.htm