The pods I do have are now about the right size for picking, but the limas inside (which can be seen when held up to the sun) are still small and flat.) (4) Should I give them extra water? Fertilizer? What can I do to encourage plumping? Last year I waited for plumping until the pods dried up and it never happened. Then the plant stopped producing because the beans had dried on the vine.

Thanks in advance! I really want some good limas this year.

The pole limas need a lot of room and do not compete well when crowded. Common pole beans will have the same issues were as southern peas and bush type bean/limas are not as affected by this. John Coykendal of Knoxville Tenn who is the farm manager for Blackberry farms and probably the best resource for limas( he is known as the Butter Bean man and has a collection of over a 100 varieties of limas). He suggest never planting pole limas closer than 3ft apart and no more than 2 plants in a hole. If you look at your vines you will see the lima starts out with one main leader then in between each leaf node another vine comes out, very quickely there is a mass of vines. if plants are too close ie more than 2 plant every 3ft apart there is way too much vine and competetion and the plants become stressed and abort blooms. If I had a 5ft long trelless I would plant two hills with 2 plant each evenly spaced on the trelliss and no more.
I plant 2rows 2ft apart with hills of 2 beans per hill every 3ft alternating from one row to the next ie one hill on left row go down three feet plant one hill on right row etc. This gives me about 125ft of beans and I produce 2crops here in SC when planted first of May. First crop is late July secound crop is in September and some years maybe a third crop late Oct early Nov. I will get 2-4 bushels on first crop and6-8 bushels on secound crop. a bushel of limas will produce about one gallon of seed when well filled out. So to break this down 40 hills average 10 bushels or about 4 hills per bushel. There is 4 pecks per bushel and 4qts fresh shelled beans per bushel so about 2 hills will give 2 pecks of pods or a 2qt of seed. A meal for a family of 4 is a qt of beans. So probably two meals in a season.

The pods will take about 3-4weeks to ripen so need to keep an I on them. The best way is like you have done let the sun shine thru and determine seed size then gage fullness by feeling the pod. It takes practice and I have picked limas my whole life and I still gage each plant while picking by opening a pod to verify fullness as I am picking. A good rule of thumb is when the first pods start to turn yellow the majority are ready to pick.
Lastly be patient the pods will fill out it takes time but be vigilant they will ripen when they are ready and not when you are so when see the first yellow pod it is time to pick.

On fertilzer too much nitrogen gives too much vine and no pods. On water use it if you have it.Rodger

One issue not mentioned above is the type of limas grown. There are two basic types of lima. The small seeded Sieva types, and the large seeded types like Big Mama and King of the Garden. While there are exceptions, as a general rule, the large seeded limas do best from Kentucky north and the sieva types do best in the hotter states from Tennessee south.

DarJones

Rodger, you may know the Butter Bean man, but around here you are definately the Lima king! :) Most on this forum focus on pod eating beans, with some shellies, runners and cowpeas thrown in for good measure. But as a Lima fan, I know I can always get good information from your posts. (and Farmerdilla too) Thanks especially for taking the time to do the math for a small gardener to give a best estimate of yield.

Susan