For your area If you have plenty of seed on hand I'd experiment and plant a little bit every 10 days. Like if you have a 10' row then plant 2' of seed every 10 days over the next 50 days. Planting in this manner can also stretch out your harvest period as the bolting process may also be staggered.

I have for many years direct seeded Black Seeded Simpson into the ground on or about St Patrick's day. This year I planted my two 9 foot rows of BSS and also 4 half rows of 4 new, to me, varieties; today. The BSS will come up enough that I can see the row and the growth always slows down, much of the time, to no growth. The BSS will start to bolt in June, the last couple years about mid June. The new varieties will be a learning process but two of them are called winter lettuce; so I'm expecting at least those two varieties to respond about the same as the BSS.

I'm in the northern suburbs of Pittsburgh, USDA zone 6a.

Here in central Va I planted my 3 types last week (BSS, Romaine, & Bibb), I'll plant them again in early April. It gets too hot/too fast down here and the leaves will start to taste bitter even before it bolts (early June at the latest). The chicken gets most of it anyways, nyuk.

When have you been planting lettuce seed before? Have you used transplants? Or just direct seeding? I have best quality success planting transplants in April, so you can pick mid to late May. You want seedlings growing in April.

You can always try, you get hundreds of seeds in a packet. It's been warm enough, but it's Ohio, it can turn cool for a couple weeks. They won't grow much with 30s and 40s temps.

If it is cold in April, the lettuce will grow slow. Lettuce grows great for me in May. In June the lettuce grows fine but tastes bitter.

I have planted a few different times. What I THINK happens is because of cool weather and little sun they grow very very slowly. They bolt before it gets really hot. They bolt before the ones I plant later. Kind of like corn. It has a certain number of days then it does what it does (produce fruit) regardless of how big the plant is. When corn had not enough sun (trying out a corner of my garden without full sun) it grew half as tall and had ears of corn 1/2 as big as normal.

So I suspect planting early and sprouting early starts the clock for when it will bolt - not based on heat. The plants were pretty much a waste of time and never got decent leaves to harvest.

This could have been because of weather that was not appropriate. The last 3 years it has been nearly impossible to grow spinach. Tiny, tiny, tiny then it bolts.

Yes, early plants will grow a flower stem earlier, but should produce many large leaves first which you eat. If the lettuce plant is staying small without good leaves, then bolts, the plant is stressed.

For me, prime lettuce growing is from about April 10th to June 10th. Long summer daylight and 80+ temps of mid June through July ruin lettuce and spinach, so you want to grow to maturity before.

All my other lettuce did great and always has. One year I tried a fall planting for spinach. None, or very little came up. The next spring I was delighted to see spinach growing there! I figured I would get a nice earl harvest, same issue. I simply do not think there is enough sunlight and warmth at that time of year. Lettuce does what it can with minimal sun & constant low temps. It simply does not grow much because it can't. Not sure but if I am right there is nothing I can do to get an early crop.

It sounds like your direct sunlight hours may be part of the problem, right now (late March) how much direct sunlight does your lettuce plot get each day?

Starting lettuce from seed indoors in early March and transplanting 4-5 week old seedlings in early to mid April is the only way I can get Romaine to head up before bolting most years and that is still iffy. I'm taking this year off from lettuce and a few other things.

I'm confused as to when they grow well, and when they don't for you. Hard to grow in shade in early Spring, if that is what you are saying. If you want an early crop, you can start seeds inside in March, plant outside in April.

I sowed lettuce Feb 17 under a little plastic tent in the garden, as I do every year around that time. It's up, starting to get its first true leaves and I've moved the tent to another spot where I sowed Asian mustards. Tent is just a metal hoop stuck in the ground with plastic over it held down by rocks. Pretty simple.

My garden gets significantly less sun in April and May then June. I suspect that is why, temps also contribute. I do not know exactly when plants do good vs not good. I do know that if I put it down before mid April not, good. After May 1st they do good. I do think starting inside is best option. It is a lot more work and I am my inside grow light area almost full with other stuff.