Hi Dawg,

I totally understand where you are coming from. I'd be interested to know if you could grow successfully with high % composts in containers as some have suggested. If the growing medium is compacting and decomposing now, then the roots can suffer in heat and lack of aeration as the temperture climbs and the mix decomposes even more as the season progresses. I wasn't able to grow/harvest mesclun in straight potting mix (too wet but my growing condition may be shadier than yours) until I added lots of perlite almost 50/50. I definitely suggest you not skimp on buying perlite, or you risk not get to harvest anything with all the investment you've made and as the temperature gets even hotter. If anything, you don't even need to buy potting mix or composts to grow lettuce (or any vegetable). You just need perlite (or coir, an organic ingredient with good aeration characteristics but can still decomposes eventually if you want to shop around for prices against perlite) and some chemical fertilizers or hydroponic nutrients. You can make your own composts. Besides, unlike other soil conditioner, perlite is easy, light, and dependable to work with and can be sterilized and reused for many years. Return any unused potting mix or composts and grow mostly in perlite (with the mix you have now) to save yourself money in the long run.

Q2: Drainage

If you have a light growing medium with mostly perlite or inoragnic growing medium with lots of air pockets, you don't need many drainage holes. In fact with a light growing medium and very little care, one can grow plants in a completely enclosed container like a self-watering container in some type of evaporation/wicking systems. You also save money on water and fertlizers and gardening with less environmental pollution. For your 15/17" by 20/21" by 8 inches deep containers and growing conventionally or in the mix you have now without added perlite, I would say at least 10-14 holes or one at every 1.5".

Q3: Shade for lettuce

Consider if you need materials and the setup to be waterproof and wind proof based on the environment you are positioning the container. Is the codition in an open space (a yard) or a sheltered and enclosed space like a balcony- and how high up, etc.? I know when I am forced to work on a shoe-string budget, I can come up with some very ingenous creations just with what I already have around. Here are some ideas: old umbrellas (or lawn chairs), widow screens lay flat on low support or in an A-frame, an inverted clear storage vin resting on stones/wood for mini-greenhouse shade and air, or growing/moving other taller plants around them.

Q4: AM or PM Shade

It depends on what kind of the lettuce. Those that are grown in partial shade and sun just need some AM sun so providing shade from PM exposure is better and more important because mid day and pm sun rays (and water stress due to higher temperature) are more intense.

Question 1: There's no need to buy small bags of perlite. Check around for Agway or Southern States Cooperative operated stores near you. They can get you perlite in 2-3 cubic foot bags. You might also get a nursery supply wholesaler to sell you a bag. I pay $18.75 for a 6 cubic foot bag of it (which will fit in the back seat of a Camry), and anyone can lift it.

You're on the right track with the aged pine bark fines and perlite. Al's recipe is all over this forum, and is great stuff.

Question 2, drainage. I don't think the number of holes and the nature of the mix have anything to do with each other. If the mix drains slowly, no number of holes in the container will speed it up. I use a number of 24" diameter pots, and they have 5 1/2" holes. They drain just fine with variants of Al's recipe. I use Pine bark fines, perlite, peat and my own compost.

Questions 3 & 4, shade for lettuce. I use three methods. One is to plant the lettuce in the shade of taller plants, like perennials in my regular flower beds. In the heat of summer, lettuce will grow with just a little morning sun, and shade the rest of the day. I start the plants in seeding cells, and plunk them in anywhere I have space for them. When I do use shade material, I prefer burlap. I bought a 4' x 250' roll about 5 years ago, and haven't gone through half of it. It's easy to rig up on poly hoops, or even just a couple of bamboo stakes. I'm in a very windy waterfront location, and the burlap works very well with the wind. It lets through enough wind to stay in place, and blocks enough light to lower the temperature substantially. Another tip is to spray the burpap with water. The condensation adds to the cooling effect under it. The 3rd method is to set up cool weather veggie beds in shaded areas of the garden. The north side of my property gets a bit of morning sun, and is shaded the rest of the day. Lettuce, snow peas and such do just fine there in mid-summer.

PS..try 'Jericho' lettuce. It's a delicious green Romaine which was developed to withstand the heat of the Sinai. It's very heat resistant. Johnny's sells the seeds.