Depends on where you are located. an elevated planting area warms up faster, keeps the ground looser, and has better drainage. Important on heavy soils like clay as squash do not like compacted or waterlogged soil. Hills is also used to describe group planting of two or more plants spaced a distance like 25 cm from the next group. The native Americans used digging sticks so they used the group planting technique as the women did all the planting.

I use hills when the seeds are old and I don't expect 100% germination. If the seeds are 1 or 2 years old I plant them individually, no hills. Also when I build my hills (I actually just had a bunch of children plant hills at a garden club today) I put a 'moat' around them to collect the water. As the season progresses if you don't mulch you will not have hills anyway they will flatten out before the end of the season. If you have a habit of overwatering or have a high water table you also want to use hills so that the base of the plants don't rot.

In the heavy, clay soil of my childhood we planted everything in hills and on ridges so that the seeds wouldn't drown in the spring rains.

In the pure sand I have right now I'm planting in basins and trenches to make sure they get some water.

I often plant my squash "in hills," but what I mean by that is, like Farmerdilla mentioned above: a group. Can't remember the last time I actually raised "a hill" above ground level. More often than not it is a depression in the soil so I can water if necessary.

George
Tahlequah, OK

I think that planting on hills is necessary if your soil is clay and/or it rains a lot. Hills also, when form a range, can provide a wall like barrier for water to accumulate and not run off. This way plant roots won't get water=loged. But if the soil is well drainer there is no need for hills. I would only hill potatoes to provide room for tubers to grow in them without getting too wet. But the roots will be way down anyway. And it is the roots that need water and nutrients not the tubers.

Thanks for all the answers! Last year I planted butternut squash in hills and though our soil is not overly sandy, it was hard to keep enough water on them. This year I planted at soil level, and they have done great to say the least - 8 meter vines running all over the place, lots of fruit setting (I'm growing Rouge Viv d'Etampes, Marina di Chioggia and Futsu). The Futsu got in a little late and sulked for a while but now it's taking off like a house on fire and lots of female flowers on the way. What's weird about it is that the male flowers seem a bit behind the female flowers (none opened yet) and I might get a female before any males! Never had that happen before..

Just wondering- would using plastic edging, like landscapers use in flower beds, etc. to make a hill work well, or would it defeat the purpose (good drainage)?

Hills (bumps) help keep cutworms at Bay as well... They're more likely to crawl straight across a space, munching along, than go upward for the stems. Great for Cukes or any plant with a juicier, less fibrous stem.