Welshonion

Sycamore trees

May burn well, but give out no heat.  Nasty trees for so many reasons!

Leeks

One year I felt quite smug as the price of leeks rose in the supermarkets because of a prolonged (that is several weeks) period of frost.  I had lots in the garden, but when I came to dig them out they were frozen in the ground!  So, if we are in for a big freeze, dig a few and put them somewhere cool, but above ground, like a shed or garage.

Otherwise they will be fine in the ground, just make sure to use them before the hard flower stalk develops when they start to grow in the Spring.

Help please

Andrew, you don't say what kind of 'ferns'.  Are you talking about bracken or ferns which grow in clumps?  You will never get rid of bracken by digging.  Chemical control is feasible or cutting down until it weakens, which will take a long time.  

Most of us do not live where the application of pigs is recommended!

Brambles can be dug out; it is the best method.  Hard work but effective.

Take care not to try and tackle too big an area at once or you will become dispirited.  Start on a small area and get that up and growing before you expand.

Getting crafty with corn

Leave them on the lawn for the birds.  Then you can compost the remains.

Gunnera manicata

Either cut off the leaves or wait until they collapse with the frost.

propagators

If you buy one check out the length of flex.  Some companies are dead mean.  And also check it will take the size of trays you will be using.

Planting Onion Sets

You can plant them out when they have a little green shoot and roots. 

Sigh!  We all want to grow better onions. Sometimes the weather is against us.

Planting Onion Sets

You can start them off in modules, which also gets round the problem of birds pulling them out of the ground.

Foxglove lutea

To find out if it is stable rather than an occasional result of cross-breeding you will have to raise several generations and rogue out any that do not conform until the foxglove breeds true over and over again.  

I hope you are a young person!

Origins of specific plants

Bean is your man, I should think. I don't know if the books are online.  Enquire in the library.

Swifts