I’ve now completed 12 monthly posts about suitable lettuce varieties and growing techniques. You can see these by clicking the Lettuce Varieties Category tab, but you can also get the overview here. They run from May to April because that’s how I wrote them. Click the name of the month to view the original post.
September is a month of change, when it comes to lettuce. We sow and transplant a lot of lettuce. The September 1 sowing is number 34 in our annual series, which runs to number 46 on September 27.
When to sow to eat lettuce in September
In September we are normally eating lettuce which we sowed from late June to mid-July. That’s a tough time for growing lettuce here, and this year was tougher than usual. We got fine seedlings up, but then they were mowed down by cutworms lurking under the shadecloth. We started new sowings in flats, up off the ground on a frame. We tried sowing baby lettuce mix to feed us during the gap. Although we sowed it in a cooler spell, it didn’t come up. We just resowed on 9/16. Now we are having a deluge – of rain, not of lettuce!
Sowing lettuce in September
From September 1-21 we sow head lettuce every 2 days. This is because the rate of growth will slow down when the weather cools, and the harvest dates of those sowings will spread out. They will all feed us through to the spring, if we protect them from cold temperatures. Before we got our hoophouse, we grew lettuce outdoors through the winter under double rowcover. It did stay alive, but we couldn’t harvest very often. Rowcover will provide a temperature gain of 4–6 degrees F (2.2–3.3 degrees C), depending on the thickness. It also reduces light transmission and airflow, but the trade-off can be very worthwhile. Lettuce can survive an occasional dip to 10°F (–12°C) with good rowcover outdoors — but not 8°F (–13°C), as I’ve seen! Adolescent lettuce are more cold-hardy than full-sized plants.
Sowings in the first week of September are for planting in cold frames in central Virginia. These days we have switched to growing spinach all winter in our cold frames, rather than continue these lettuce plantings. We get better value from spinach. It grows faster than the outdoor (rowcovered) spinach, but slower than our hoophouse spinach.This means that after the last sowing for transplanting outdoors, on August 29, we get a short break on lettuce sowing.
We resume with number 38 on September 9. The sowings from 9/9 to 9/17 will be transplanted in our greenhouse. We also sow on 9/15 and 9/24 to transplant into our hoophouse. The sowings from 9/19-9/27 are “insurance plantings” in case something goes wrong with an earlier [planting, or we don’t get the greenhouse beds refilled with compost soon enough, and want smaller plants.
Lettuce varieties to plant in September.
From September 1-7, (the coldframe ones we used to grow), we use cold-hardy varieties Green Forest, Hyper Red Wave, Merlot, Midnight Ruffles, New Red Fire, Oscarde, Panisse, Pablo, Red Salad Bowl, Salad Bowl, Winter Marvel (a Bibb) and Winter Wonderland (Romaine). Pablo is a hold-over from the summer Batavian lettuces. (Heat-tolerant varieties also tolerate cold.) There are also specialized cold-hardy varieties that do not tolerate heat (because they have a relatively low water content). Sow these in fall and winter only.
The salad bowls do fine in the greenhouse and the hoophouse, although I remember they are not cold-hardy enough for growing outdoors here. During the winter we will be harvesting lettuce by the leaf, rather than cutting heads. Green Forest, Kalura and Winter Wonderland are romaines that do well in the winter for us. Note that we don’t grow butterhead lettuce (bibbs) after the end of August.
Once we reach September 8, we are sowing lettuce for planting in the (unheated) greenhouse. We use Green Forest, Hyper Red Wave, Kalura, Merlot, Midnight Ruffles, New Red Fire, Oscarde, Panisse, Red Salad Bowl, Red Tinged Winter, Revolution, Salad Bowl, Tango and Winter Wonderland.
For the hoophouse winter lettuce, we sow Osborne multileaf lettuce types (Multigreen 57, Multired 4, Multired 54), Green Forest, Hyper Red Wave, Merlot, Oscarde, Panisse, Red Tinged Winter, Revolution, Tango, Red Salad Bowl, Outredgeous, Salad Bowl, Winter Wonderland Romaine. For the second sowing on 9/24, we use Include all the same ones except Oscarde, which has given us trouble in the past when started that late.
Small and medium-sized plants of Marvel of Four Seasons, Rouge d’Hiver, Winter Density, and Tango can take 15F (-9.5C). I’ve seen some small unprotected lettuces survive down to 5F (-15C) – Winter Marvel, Tango, North Pole, Green Forest. Other particularly cold-hardy lettuce varieties include Brune d’Hiver, Cocarde, Esmeralda (a bibb), Lollo Rossa, North Pole (bibb), Outredgeous, Rossimo, Sunfire and Vulcan.