One of our very favorite crops to grow is lettuce. It’s so easy to grow! You can grow lettuce nearly anywhere, but to get a large harvest from growing in containers, we love growing it in our GreenStalk Vertical Planters. We grow mixed lettuce, heads of lettuce and baby greens every spring and fall. There’s just nothing like harvesting your salad straight from your garden! Keep reading to find out our top tips for growing lettuce vertically.
How to choose a good potting mix for growing lettuce
This is soooo important! Don’t use heavy dense soils for growing lettuce (or really anything in containers). Look for lightweight mixes that have peat moss, compost, coconut coir, perlite, etc. You’ll need 1 cubic foot or 8 gallons per tier. We like Happy Frog and Pro-Mix, and several of our customers swear by Miracle Gro. But whatever you choose, just be sure it’s a mix that is formulated for containers and includes starter fertilizer. If it doesn’t include some starter nutrients, pick up an all purpose mix at the same time. You can choose a granular fertilizer that you can add while planting, or you can choose a water soluble mix that you can add as needed through the GreenStalk’s watering system.
Once you have your potting mix selected, fill each planter up to the top with potting mix. There’s no need to “pack” the soil into the planters as it will settle over time. Wait to water until after stacking.
Growing lettuce from seed is easy
We ALWAYS grow lettuce from seed. This is especially helpful when growing vertically, because starter plants add up fast and there’s a lot of pockets to plant in a GreenStalk Vertical Planter! We plant 2 seeds per pocket for large lettuce head varieties and up to 8 seeds per pocket for baby greens or mixed lettuces. We just sprinkle the seeds over the soil and cover very lightly. You can seed in the lettuce before or after stacking, it’s totally up to you.
We also don’t typically thin out our lettuce seedlings unless we are growing for a single large head of lettuce – in that case you’ll want to thin to one plant per pocket.
Finally, stack and water your vertical garden
Stack each of the tiers together with a grey watering disk between each tier and the top water reservoir locked in on top. Take care to ensure the grey disks are clean and that the GreenStalk is stable when assembled. If it’s not level or if something feels loose, make sure all the tiers are interlocked together.
After stacking, it’s time to water. Fill the top water reservoir to the amount of tiers that you have with a bucket or a quick filling hose. In addition to the watering system, or instead, you may want to use a spray bottle or watering can to hand water each of the pockets. Once your seeds sprout, you can use the watering system exclusively. We find that handwatering can help increase germination rates. You don’t want those seeds to dry out!
How to harvest lettuce and harvest again
Lettuce is one of those wonderful crops that you can harvest from multiple times. Even heads of lettuce will regrow if you let them. We use a sharp knife and cut the lettuce in a straight line parallel to the soil leaving about 1-2″ of the lettuce stem so it will have something to regrow from. You can also harvest lower leaves if you’d rather not cut the plant all the way back.
Lettuce does get more bitter as you continue to harvest. We can usually get up to 3 cuttings per plant – if we cut the plant all the way back. We harvest every 2 weeks until the plant turns bitter or bolts.
Troubleshooting common lettuce problems
Bolting: this happens as the weather warms. Lettuce is a cool-weather crop and should be grown in spring and fall in most areas. Typically, we can’t grow lettuce past May in our area (zone 7). When you see signs that the plant is forming a single stem and shooting up through the center of the plant, you’ll want to go ahead and harvest. The longer you wait, the more bitter the lettuce becomes.
Yellowing leaves: if this happens, you have a nutrient issue. Fish emulsion works great at giving your lettuce a nitrogen boost. It smells bad right after adding it to your vertical garden, but the smell goes away after about a day.
Wilting plant: the most common cause of this is overwatering. Lettuce is mostly water, so they will need a good amount of water. Don’t let the soil dry out completely between waterings. We find in the spring and fall months we have to water every 1-2 weeks depending on how much rainfall our area gets. Of course now that we are in a greenhouse it’s more like 1-2x a week since we don’t get the help of rain to water our plants for us!
What are your tips for growing lettuce? Let us know in the comments below!
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