I planted my hawthorn tree 3 years ago and it has never bloomed or grew berries, and it get a leaf disease. Could this be a reason?
Check to see if you have a grafted stock tree. A grafted Hawthorn should bloom in 4 to 5 years.
If it is a seed grown tree you will need more patience, it can be 20 years before it blooms.
Here are a few links for you with some good care information.
https://www.gardeningknowhow.com/ornamental/trees/hawthorn/growing-hawthorn-trees.htm
https://www.gardeningknowhow.com/ornamental/trees/hawthorn/pruning-hawthorn-trees.htm
Can you start a 2nd tree from suckers of above ground growth? How do you do this, as I've tried with rooting powder and really good soil to no success. Advice, please?
Yes, you can. Make sure your cutting utensil is clean and sharp. Remove softwood stems at the nodes. You want your cuttings to be between 4 and 6 inches ideally. Strip the leaves from the lower half and dip the end in your growth hormone. Peat moss and soil (heavy on the peat) make an excellent media for propagating. Moisten your soil mixture and use a pencil or another stick to poke holes so your growth hormone stays intact. Place each stem in the holes. Put the container where it will receive indirect light. Make sure to maintain a moist soil (not drenched and not dry). Check for rooting in about 2 months then pot up each Hawthorne individually when roots are at least 2 inches long. Hope this helps. Good Luck!
Hawthorn plants are 30 years old - a few have died - some are declining. Can anything be done to save the sick ones?
I don't know what the symptoms or stresses that your trees are suffering, but here are some links to refresh you on the care requirements.
https://www.gardeningknowhow.com/ornamental/trees/hawthorn/growing-hawthorn-trees.htm
https://www.gardeningknowhow.com/ornamental/trees/hawthorn/pruning-hawthorn-trees.htm
Assuming there is a disease like cedar rust, can I cut the branch now rather than waiting during the dormant season so it stops the spread? Our tree is matured just so you know.
Here are some links and articles that have information on care and common pests and disease of Hawthorn Trees.
https://www.gardeningknowhow.com/edible/fruits/apples/cedar-apple-rust-control.htm
https://www.ipm.iastate.edu/ipm/info/plant-diseases/cedar-hawthorn-rust
https://extension.psu.edu/pests/plant-diseases/all-fact-sheets/hawthorn-diseases
https://www.gardeningknowhow.com/ornamental/trees/hawthorn/growing-hawthorn-trees.htm
How farr from house and waterline should tree be planted?
No closer then 8 feet from the home or corner of the landscaping.
I have a standard Hawthorne tree what is the rate of growth each year.
This tree grows at a medium rate, with height increases of 13–24" per year.
https://www.gardeningknowhow.com/ornamental/trees/hawthorn/growing-hawthorn-trees.htm
I am considering artificial grass in the two narrow strips of land near the street curb in front of my house. There is a Cockspur Hawthorn in each strip of land. These little trees have been there for 5 years. They are healthy and provide a good screen between my house and the street. I do not want to destroy them, but I would like artificial grass to cover the hard-to-maintain soil around them. It is very hot in those areas in the afternoon in summer and I have found nothing that will grow around those trees. The plots look shabby. Would artificial grass be a safe application? Thank you, Ann Luke
Most of the research shows that placing artificial grass or turf over mature tree roots, and right up to the tree trunk pose no threat to the tree.
No research that I found had any specifics with tree type, so it's effect on a Hawthorn Tree, I could not verify.