
I need to plant something 6" apart.
If I have a 2W x 2L bed, my plant count is 9, assuming 6" in from the edges of the bed. Ratio: 9 plants : 4 sq feet. If I extend the bed to 2W x 4L, my ratio goes to 21:8 If I extend to 2W x 6L, the ratio becomes 33:12 How many square feet do I need to get 1,000 items in, if the bed is not extended to more than 4 feet wide? I know this is probably a 5th grade ratio question, but I'm apparently not smarter than a 5th grader, and I have afternoon mushbrain. Help. Thanks. 
FollowUp Postings:

If you do not want to go any more than 4 square feet  and you want all the plants spaced 6" apart  including 6" from the edge of the bed, that would be plants at: 6"  12"  18"  24"  30"  36"  42" Basically that is formula like the following ((number of feet of bed width * 12) / (spacing per plant))  1 You subtract 1 at the end because of the spacing from the edges of the bed. You effectively lose one spot for planting an item. That means you would get 7 plants per 1' x 4' of bed. (again, 6" from the edges  so you also lose 6" of space no matter the length of the bed). So, a similar formula is used for the 1,000 items. (((Number of items / items available per row) * inches of item spacing) + inches of item spacing)) / 12 You have 1,000 / 7  which gives you the number of rows you need  that is 142.8 rows  lets round up to 143 rows. Now, you need to take 143 * 6 (for the inches of spacing) and add an additional 6" for the spacing from the edge. That equals 864 inches of space needed. Divide it by 12 and that gives you 72 feet. So you need a bed 4 feet by 72 feet long to plant 1000 items planted 6" apart with 6" on all edges of the bed before the first plant. 
Here is a link that might be useful: BsnTech Gardening Blog

bsntech THANK YOU! I managed to get to the "times 2, minus 1" stage of the equation for plants per row. Somehow I ended up with 7 x 17 plants in a 4x8...and 7x13 7' bed...somewhere along the line I decided I needed around 10 of those 4x7s...so I guess I wasn't that far off after all. Thank you for providing the algebra (ha, and Peggy Sue (1986) said we'd never need algebra again!) Moochie Gracie! 

Yep, your math with the 4 x 8 was off by two  you are adding an additional row when you should have been subtracting. With an 8foot length, that would give you 15 rows  (8 x 12) / 6 is 16  then subtract one for the spacing from the edge  which is 15. So you'd have a 7 x 15  or 105 items planted in that area at 6 inches apart. Your math on the 4 x 7 foot bed was correct... (7 x 12) / 6 is 14  subtract one and that gives you 13 rows; a total of 91 items possible there. 
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