How long can I keep a female pinecone before planting the seed in it? Do I have to wait till the first of year to plant? If so, how should it be stored in the meantime?
You can plant them immediately or store them, whichever you prefer. Here is more information: https://www.gardeningknowhow.com/ornamental/trees/pine/how-to-grow-a-pine-tree-from-seed.htm
If I use roundup and salt to kill tree roots on the cut tree, will that affect the roots on adjacent trees which are Austrian Pines?
Care needs to be taken not to spill or slash any chemicals onto the grass or other trees.
If you carefully paint the cut root ends then only those roots will take up the chemical.
I am worried about parking my car under some pines that line the driveway. Is there a time of year when they release the sap/pitch?
The sap of the tree can be seen more in the warm months of the year but sap is always flowing in the trees as it carries nutrients throughout the tree.
Here are some links for you.
https://www.gardeningknowhow.com/ornamental/trees/tgen/what-is-tree-sap.htm
https://www.gardeningknowhow.com/ornamental/trees/tgen/how-to-remove-tree-sap.htm
I've lived in an apartment with a very large pine tree (I'm guessing 30 years old or more) above my parking space for 10 years. Sap has always been an issue but only the last 2 years I've had a problem with pine cones falling on my car. One put a crack in my windshield. Why is it only a recent problem and do pine trees have a pine cone producing spurt that I can hope will be over soon? I live California under drought conditions.Will this cause the tree to produce more pine cones?
Conifers produce different amounts of cones each year.
As the tree ages it will generally have years of larger amounts of cones produced.
Research does suggest that stressed trees will produce more cones.
I have a large prostrate pine that has died. The bark flaked off and there are 'bug trails' in the surface of the wood. Will this spread to other pines? What is the time frame for killing these bugs and what will work?
Correctly identifying the disease or insects is key to any possible treatments.
Here are some links that may help pinpoint the cause.
Consulting a certified Arborist to help make the correct diagnosis may be the best solution, especially if more trees may be involved.
Contact your local County Extension Office, they are a valuable source of information on the local management of diseases.
http://www.na.fs.fed.us/spfo/pubs/howtos/ht_pinewilt/pinewilt.htm
https://extension.psu.edu/pests/plant-diseases/all-fact-sheets/pine-diseases
https://www.gardeningknowhow.com/extension-search/
How long does it take for a pine to reach 10 feet height?
This will depend on the type and variety of Pine Tree you are growing.
White Pine grows faster then other species, growing 8 to 12 inches per year.
https://www.gardeningknowhow.com/ornamental/trees/pine/caring-for-pine-trees.htm
I have some sort of pine trees in my front garden - they stand about 6 feet tall and are getting wider and wider. This is the problem. I want to trim them up but the insides of them appear to be nothing but dead branches. I'm thinking if I take the hedge trimmers to them I'll end up with 6 ft tall dead branches. What am I supposed to do (short of ripping them all out)? Thank you.
I have similar issues with Blue Spruce in my front yard.
We have opted to remove all the lower branches about 8 feet up. This distance allows us to walk under the trees, mow and still leaves enough branches so that the trees don't look like umbrellas.
Here are some articles that will help you.
https://www.cals.uidaho.edu/edcomm/pdf/BUL/BUL0644.pdf
https://www.gardeningknowhow.com/ornamental/trees/pine/white-pine-tree-information.htm