Here in the PNW, we have had relatively mild winter the past 2-3 years. Artichoke, kale, cabbage, arugula and dahlias have overwintered in my garden 3 years in a row. I personally do not garden after October 31st because it is too cold for my fingers to operate effectively.
Fall gardening poses several challenges. The water at MCGA is turned off in October so if you want water, you have to collect it at the garden via rain or lug it from home. The sun is low in the sky and we just do not get many hours of light. The weather turns cold and most plants do not tolerate the cold well at all. There are some that like cooler weather such as greens like lettuce, spinach and arugula. Plant these seeds in mid-August to early September and you will likely get a nice crop before the frost hits.
If you want to garden past the frost date you will have to take extra precautions to make sure your plants do not freeze. See below for some examples as well as their pros and cons.
Cold frames are the best at keeping the cold out. They keep your plants very cozy and are easy to open when you need to water. When made of glass they can get very warm so it is best to purchase a venting mechanism to open and close the lid/top when the temperature rises and falls (yes, there is such a thing.) They are heavy and usually live in one place in the garden. You can buy pre-fab kits or you can make one yourself. They are not cheap and take a bit of know how to build although I have seen some clever recycled versions.
(This cold frame is made from bricks and old windows.)
(This cold frame is made from straw bales and old windows.)
This is a hoop house, Plastic PVC pipes are bent and place in the ground then plastic or Reemay types of garden fabrics are placed over the hoops and pinned down. This is a super easy and cheap way to trap heat for your plants. Make sure you use the thickest plastic and fabric you can afford, the thicker the better. Plastic can heat up quickly so you have to watch out for scorching and they do not let water in. You will have to open up the hoop house to water every time. Fabrics are better, they let water and air in so problem of overheating is minimized.
(This is a Reemay hoop house)
(Here is another style of hoop house, when made small and light enough, the entire top can be lifted to water and harvest. When a big wind comes however they may blow away.)
(I do not recommend using gallon jugs are they are too small and may blow away, It is also hard to water into those tiny openings at the top of the jug. The space is often too small for many plants.)
Whatever method you plan to use for gardening in fall/winter remember these important points:
When selecting a winterizing covering consider is how airtight it is. The less permeable it is, the warmer the trapped air remains on cold nights. On the other hand, airtight cloches demand more attention to prevent overheating and possible death to your plants. Air tight coverings also do not let water in.
If you live in snow country also consider how well it will stand up under the weight of snow. ( We don't get much snow but you never know.)
Consider also the material from which the covering is made and its durability. Lightweight plastics may last only a year or two but thicker plastics, especially if the plastic has been treated with ultraviolet light inhibitors, might last 5 years or more. Glass lasts forever if it doesn't crack first.
Finally, consider what you'll do with the coverings when they're not in use. Do you have the room to store everything when summer hits? Ponder these thoughts as you plan your next season, see you next spring.