Tips for Success with Organic Lettuce, Spinach and Radishes
The salad crops are some of the easiest vegetables to grow in most gardens. Besides being easy to grow, they’re also quite cold-resistant, so now is the time of year to get them growing in your garden or containers (oh yeah, they do well in containers too!)
If you do want to try your hand at container gardening this year, you might want to read my post on Growing a Vegetable Garden in Containers as well.
General Lettuce (Lactuca sativa) Information
Lettuce has been around for a long time. Pictures of it were even painted on Egyptian tombs!
As with most other vegetables, the darker the leaf, the more nutrition it contains. This is why I call Iceberg “crunchy water”. Yeah, we don’t eat much Iceberg in this house.
How to Grow Lettuce
Lettuce likes lots of nitrogen (that’s what gives it the nice green leaves). Therefore, a soil very rich in compost or other organic matter is ideal. Don’t be afraid to be really generous with the organic matter, your lettuce will thank you.
This is week four of my Crop of the Week series. If you’ve missed them so far, you can head on over and read about Growing Peas, Growing Beets, and Growing Brassicas (cabbage family crops) by clicking on the post titles. There are FREE printable cheat sheets on each of these crops, as well as other goodies, in my Subscriber’s Resource Library. Not yet a subscriber? Head on over here to see what it’s all about.
When to Plant
It’s better to direct sow lettuce 1/8″ deep where you want it to grow, which typically works well as you can plant lettuce quite early in the season, at least 2-4 weeks before your last frost. Assuming you’ve selected a variety or collection that is a “cool-season” or “winter mix”, soil temps only have to be 35F for it to germinate!
If you like butterhead lettuce (and if you haven’t had it, trust me, you’ll like it!), both ‘Big Boston’ and ‘Brune d’Hiver’ are particularly cold-hardy varieties.
That said, if you happen to get a late start on your lettuce or you live in a warmer region, there are also varieties and mixes that are considered “warm season”, which would be ideal for you. ‘Summer Bib’, ‘Green Salad Bowl’, ‘Red Deer Tongue’, and ‘Little Gem’ are all more heat-tolerant than most.
A note on why you should care whether your lettuce is heat-tolerant: If lettuce gets too much heat, it bolts. This simply means that it sends up a flower head in order to produce seed. The problem is that once this happens, the lettuce leaf becomes bitter and inedible. Therefore, you want to pay careful attention to which varieties you’re planting based on time of year and the climate where you live. Also, heading types tend to bolt faster than leaf types.
Ideal Growing Conditions
Your plants will appreciate some afternoon shade in all but the coldest of climates, so plan accordingly. If you have nowhere appropriate to put them, you can always use row covers. It’s best to leave the ends of the row covers open for air circulation though.
Temperatures of 50 to 70 degrees are ideal for lettuce, although I’ve grown it successfully in very warm summer weather with protection from the hot afternoon sun.
If you’re growing in containers, you have the advantage of being able to move the containers into the shade as the weather gets warmer.
Thinning, Water, Mulch and Fertilizing
You’ll want to thin your seedlings to about 4″ apart once they’re big enough to handle if you’re growing leaf lettuce. If you’re growing head lettuce, thin them to a foot apart to give them room to expand. Don’t throw those thinned plants away though, they’re delicious in salads!
Because lettuce is primarily water, be sure not to let it dry out. You want your plants to receive an inch of water every week throughout the growing season.
Mulching is a good idea because it cools the soil, but if you have a slug problem, mulch will make it worse (more on slugs below).
Lastly, your lettuce will appreciate it if you side dress it once or twice during the season with some fish emulsion.
Lettuce Pest Problems
Because lettuce grows in such cool weather, it usually doesn’t have many pest problems.
That said, a pest you may encounter is slugs. Not mulching your lettuce will help keep them at bay. You can also hand pick them, and leave shallow saucers of beer near the affected plants to attract and drown the slimy little buggers.
Another possible pest you may see is aphids. Here in Zone 6b, I don’t typically see aphids early enough in the season for them to trouble my lettuce, but companion planting with chervil may help to protect it.
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Harvest, Storage and Use
It’s easiest to cut lettuce about an inch above the root with a sharp knife. This harvesting knife will make life easier, trust me! However, be extremely careful not to catch one of your fingers with it while you’re using it (trust me on this too!)
Even heading types can be harvested for leaves for several weeks, if you prefer. Just cut the outer leaves and let the inner ones continue to grow. If your lettuce starts to bolt, cut the entire plant immediately.
Store your lettuce in the refrigerator after harvest. As you’ve probably read in other posts, I love these Debbie Meyer Green Bags.
I always cut my lettuce right away in the morning (it IS actually sweeter first thing in the morning, that’s not your imagination! It’s a consequence of the incredibly complicated process of photosynthesis, and since I want you to keep reading, I’m not explaining. Sorry….or you’re welcome, I suppose).
Anyway, I wash my lettuce and place it in my salad spinner. I always thought salad spinners were kind of silly, but they’re great for getting the excess water out of leaf lettuce. If you’re storing it for any length of time, it’s best to get as much water off as you can.
I also place a paper towel in the bottom of my green bag before I add the lettuce, and it keeps for close to 2 weeks.
One note: Don’t store lettuce close to apples. Apples emit ethylene, which causes brown spots on leaves and hastens spoilage.
Of course, most lettuce is used raw in salads or on sandwiches. However, one variety called celtuce gives you some other options. I’m going to try it in my garden this year because it sounds intriguing.
Celtuce is usually grown for its stalks, not its leaves, as the leaves are somewhat bitter. The stalks must be peeled, and the interior is said to be quite sweet and crunchy, much like a water chestnut. It can be sliced and eaten raw, or stir-fried. I’m looking forward to giving it a go!
I got my celtuce seeds from Baker Creek Seeds, but you can also find them here, if you’d like.
Best Growing Conditions for Spinach (Spinacia oleracea)
Spinach likes it cold! You can plant it 4 to 6 weeks before your last frost, and the young plants can tolerate temperatures as low as 15F! Unfortunately, this also means that it DOESN’T like heat, and may stop growing entirely when temps reach roughly 70F.
But I want Spinach all Summer!
You are in luck, my friend. You CAN have spinach all summer long! OK, well, technically it’s not actually, botanically spinach, but New Zealand Spinach (Tetragonia tetragonioides) looks and apparently tastes quite a lot like spinach, and is heat-resistant to boot. If you check out this link to Baker Creek Seeds, you can even read reviews from people who have grown it.
I haven’t grown it myself (yet!) so can’t speak to how it does, but it seems to be a good alternative for my southern friends who will have some difficulty with the traditional kind.
Spinach Planting and Care
You should plant spinach seeds directly into the garden where you want them to grow. Because spinach is tap rooted, it doesn’t transplant well. However, like lettuce, you want nice lush green growth on your spinach, so be sure to plant into soil that’s been amended with lots and lots of compost to give it needed nitrogen.
I’ve found spinach to be a bit difficult to germinate. At a minimum, I would suggest soaking the seed for 24 hours before planting.
However, this year I’m trying something different. I’m pregerminating my seeds in a very damp paper towel inside a plastic bag. Right now, they’re sitting in a kitchen cabinet. I’ve been checking them every day, and as soon as I see that they’ve germinated, I’ll plant them in the garden.
UPDATE: They germinated and I planted them. About a week later, I had almost 100% of them coming up, so I think presprouting in paper towels is the way to go with spinach.
When you do plant your seeds, plant them 1/2″ deep and about 4″ apart. Once they’ve come up, thin them to 6-8″ apart. You can try planting every 2 to 3 weeks until the weather warms to 70F.
If you live in a warm climate, you might have better success planting your spinach in the shade of other, taller plants, like corn or pole beans. I would think even tomatoes might give it the shade it needs.
A nice layer of mulch will help keep your spinach cool. When temps really heat up, you can try to extend the season by covering your plants with shade cloth as well.
They will also appreciate a nice bit of compost tea or fish emulsion once they have four true leaves.
Just a note in case you don’t know what “true leaves” are: When a plant first comes up, you’ll see (typically) two leaves first. However, when the next two leaves appear, you’ll notice that they look very different from the first two. That’s because the first two leaves aren’t “true” leaves, they were contained in the seed and were there just to get the seedling started. When you’re counting “true” leaves, don’t count the first ones.
As with lettuce, because it grows during cooler weather, you likely won’t have any serious problems with pests.
Should you notice “trails” within your leaves, you have leaf miners. The easiest remedy is simply to cut the affected leaves off and destroy them.
Saving Spinach Seeds
If you’d like to save seeds from your spinach, only let one variety go to seed at a time, as they will cross-pollinate.
Let quite a few plants go to seed so you get a good genetic mix, and save only those seeds from the latest bolting plants. You want, of course, to propagate those that bolt later, since bolting is as undesirable in spinach as it is in lettuce, for the same reasons.
Let the seed heads dry nicely, then cut them off, put them in a bag and crush the seed heads to remove the seeds. Store in a cool place, as you would all seeds.
General Radish Information
There are two different types of radishes, the salad type (Raphanus raphanistrum) and winter type (Raphanus sativus). Varieties of the salad type include ‘French Breakfast’, ‘White Icicle’ and “Purple Plum’. Winter radishes include ‘Red Bartender’ and ‘Japanese Minowase’.
I’m going to cover primarily salad types today as winter types are best planted later in the summer for a fall crop. Don’t worry, I’ll be talking about mid-summer planting for fall crops later, I promise!
Radish Planting and Care
Radishes are seriously so easy to grow, it almost seems silly to talk about caring for them! You can give them their own dedicated bed or plant them throughout your garden, as they do well as companions with many other crops. They do appreciate nice, rich soil, so be generous with the compost before you plant.
You’ll want to plant your radish seeds 1/4″ to 1/2″ deep and a couple of inches apart in full sun. They’re a cool season crop, so can go in at about the same time as your lettuce (I planted my first round this past weekend, about four weeks before last frost).
The nice thing about radishes is that they’re not quite as picky about temperatures as other cool season crops. You can safely sow some every two weeks until September, pausing in high summer if your temperatures routinely get above 90F.
One thing about radishes is that if they should get dry and stay dry, they get angry. Yup, they do. You’ll know this because they’ll get all bitey and hot when you try to eat them! To that end, be sure to give them consistent water. As with many other crops, an inch a week is good.
Saving Seeds of R. raphanistrum
As with the other salad crops, only let one variety go to seed at a time to prevent cross-breeding. It’s a really good idea to let some of your radishes go to seed anyway, as the pollinators love them!
Again, seed saving is easy, just allow some of the seed heads to mature and dry on the plant, clip them and put them in a bag, then crush to release the seeds. As always, store in a cool, dry place.
I hope this post has been helpful. As with my other Crop of the Week posts, there is a FREE printable with all of the post information in condensed format in the Subscriber’s Resource Library. Not a subscriber, you say? Well, head over here to see what it’s all about.
Posts Related to Growing Organic Salad Crops
- Successfully Grow Organic Peas
- Growing Organic Beets
- Growing Brassica Crops
- Grow a Vegetable Garden in Containers
- Subscribers Resource Library Information
- The Last Garden Journal You’ll Ever Need
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