Hello davenmidtown, I would agree with troyangeluk.
The old hubs,may be modified and rewritten to update them. That is much better for your Search Engine visibility.
Funny that in a world of new, new, new. Search engines actually like old. It shows some permanence and like with any job you have a kudos when you have longevity with a single employer, rather than being a job market butterfly.
You could tweek a few of Googles suggested keywords in there, you could use them to link to or from blogs, driving traffic around.
It may be the hubs were also seasonal? I enjoy your hubs about the garden, but they are for particular seasons, not bad in general because people can refind them year after year but it does give you a more cyclic pattern for some of your hubs.
You could always go back every few months and refine the links to include newer hubs, moving one or two links around and linking to other work does increase views to old hubs and their age adds more credibility to your latest hubs.
Be sparing with linking though do one or two slowly rather than ten or more at one time, search engines don't like too many links appearing at once. But you can't tell how many is too many until it is already too late.
Hope this helps.