I don't think what you are asking will work. The simple solution would be to use what you have. Your lights and seed trays, if you use standard seed trays, will only hang over the sides of the shelf a few inches on each side. You should be able to fit two fixtures on each shelf. Just make sure you have enough light to cover the seed trays you use.

Could just be rounding. A ratio of 4:1:5 is equal to a ratio of 2.7:0.7:3.4, which would round to 3:1:3. TomNJ

They should have already asked if they could contribute...so I think the jar in a very prominent place would be the ideal solution. Some ideas (to keep it easy and casual)... 1) A stack of paper plates, loaves of white and wheat bread, luncheon meats or prepared tuna, chicken salad, or pimento, mayo, mustard, and chips. 2) Big bowl of salad greens, bottled dressings, croutons, cherry tomatoes, grated cheese, green onions. 3) Plate of taco shells, bowl of cooked ground beef, shredded cheese and lettuce, and salsa. 4) Big plate of crudites (broc, cauli, carrots, green onions) and dip. 5) Rotel dip and chips. (It's filling!) I think all these are quick, easy, and after all, they aren't there for a full meal, right? Help yo'self, folks!

I'm with Humsi 100%. Leaving a healthy garden with a 10 day weather forecast, 3weeks is not such a big deal with a plan. bronxbill just asked about tomatoes. But did not mention when the three weeks away begins. If soon, and in the month of June, i see no issues. In the NY area we get on average an inch-2 rain weekly. You can have your cake and have a vacation and a garden. The best method is a simple soaker or drip system on a dial timer and show a neighbor the timer if no rain has occurred in a few days. They just need to turn it on for 1/2 hour-45 min depending on your flow. A self timer is ok but it will water even when not needed. Just get the system well ahead of time so it can be tested. Tomatoes do best under-watered than swamped. I have to leave all the time during the grow season and i just watch the weather while away, then text or e-mail one of two neighbors to turn on the timer. If weather turns hot and we have an unusual drought i have a back-up plan. I just returned from 3 weeks away last night. No watering was needed as i watched the weather. One neighbor added water in my tomato start trays just once mid-trip. All 120 starts look good but i blame no one if something went wrong. It really depends on your climate and the time of the season away. August a few years ago i had a local nursery employee check on things. He scored a bounty of produce. I was willing to pay but after dealing with customers all day he enjoyed a walk through my garden in peace and quiet twice a week. If dry he turned on the drip system right away and harvested. Only once did he leave it on 24hrs. (my water is free). A sprinkler is fine if you know what you are doing. Can be expensive and horribly inefficient in most parts of the country. Not the best system during holiday. Drip systems are very affordable these days. Customizing each plants water needs and can be added to anytime.