Vining plants usually have deep roots; in addition, in your climate it will be difficult to keep enough moisture in a wide shallow container only six inches deep.

Six inches deep is fine (all of my raised beds are 6" even the ones built over concrete). You can grow just about anything in 6 inches as long as there is enough space for roots to grow horizontally. I wouldn't grow the watermelons in the container but you should do fine with the cucu. If you are into container gardens, but want toms and mellons, use a hardware store's 5 gallon bucket with compost and vermiculite! Good luck!

I think a 5 or 6 inch container will be very difficult to keep enough moisture in, in the desert even with plenty of horizontal space.

I grow in a climate on the edge of Death Valley. 6" can be done. For irrigation I would recommend a drip system. here is my 6" raised bed that is drip irrigated shot this morning. Shown are garlic loving today's weather :)

All 6" beds shown here this past summer except that brick bed which is about 12" ish, I'm not sure I haven't measured it... :) About 110F here in the summer. I watered 4 times a 24 hour period for 7 minutes each cycle. Good luck!

Thank you all for you great advice.
I think I will try out with both. 12 inch as well as 6 inch. Lets see how they compare.

LoneCowBoy:
Since I too live in a desert climate, perhaps you can help me with these question which I have been trying to get answered for some time now.

I just checked the monthly average temps that you get in Desert Valley and compared it to mine and it was practically like I was seeing an Al Khobar, Saudi Arabia Climate chart.

1/ Do you really garden during the months from June to September? Infact May could also be a trouble month. Checked wikipedia and got this monthlyu average temperature Highs:

66.9 Jan
73.3 Feb
82.1 Mar
90.5 Apr
100.5 May
109.9 Jun
116.5 Jul
114.7 Aug
106.5 Sep
92.8 Oct
77.1 Nov
65.2 Dec

2/ How do you control the heat and what is that you grow? especially the edibles?

3/ Have you ever tried summer greenhouses? or thought about it?

4/ Have you tried growing sun loving veggies in shade during these 4 months? Do they work?

Thanks a lot.

lol fortunately we live in a micro climate corridor and only peak at about 110 a few days and avoid the 116.5 averages :)

I grow year around. Most Tomatoes, peppers, gourds, egg plants, melons, sunflowers, most varieties of beans, corn, all do well in full sun so the temps really do not bother my plants as long as the there is sufficient moisture. The heat WILL ruin growth in most cruciferous vegetables so it is important that you start them indoors about 5-6 weeks indoors so they can finish outdoors right before the heat wave.

I do not have room for a greenhouse but I would love to have one! Perhaps in a a few years, we may locate to a larger property where one could be built.

To combat the heat, I grow herbs and greens on the north end of my property about 4 feet away from the house. This allows morning sun, but shades out the afternoon heat. Growth was great but the arugula was intolerably spicy during the summer (although a chef friend tried it and was in heaven, so each to their own...).
Another thing I have done this year is move my tomato bed under the shade of some trees. (See photo. Sorry for how awful the photo looks. We had a storm last night and are expecting another for the next 2 days). With 8 plants in a 10.5'x3.5'x6", I've set up 7' cages and with the combined tree shade (NOT VERY SHADY!) and tomato foliage, I anticipate natural heat management will increase yield. Keep in mind that I did not have problems growing in full in 110F, but I believe this may also have been due to the variety of the tom. I've read you have to be careful about temps in the mid 90's, this is the reason for the move.

Yes, I tend to grow sun loving veggies in full sun and then not so sun loving like greens in the back as previously mentioned or start them inside and transplant to finish in the first few months after the anticipated last frost. I try to grow year around but you have to be selective as to what you will grow during what season. This past year, my winter growing was limited to collards, kohlrabi, onion, and garlic. Not exactly the good eats ;) but never the less, I grew something! Gardening is an adventure and each year its important to learn and make adjustments. Installing a drip system has ultimately made growing here possible. Watering at 5am/pm 11am/pm for 7 minutes worked well. The auto timer is a life saver.

Also don't discount the enriching power of soil microbes and fungi. I'm a strong believer in compost teas to inoculate the soil and foliar feed with micro nutrients for vigor.

Thanks LoneCowboy

For a beginner like me, can this be concluded that as long as I am providing shade (partial or complete?) after 4 hours of morning sun and ensuring that the plants are hydrated, it should hopefully work out?

My worry is while the soil temperatures can be controlled by watering and shading, the air temperatures around the leaves and flowers would still be above 100 - close to 110 even? Is this a thing to worry?

Regards

Saood