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| Red Iceberg Lettuce - a summer rose! |
This post gives generic information for starting cool-weather crops (lettuce, cabbage, broccoli, kale etc) from seed.
Here at the Sharing Gardens (in the Pacific NW) we have several ways of starting seeds.
This post is about starting them in a grow-tunnel or greenhouse using re-purposed tofu containers to get them started. (To read about
Starting Seedlings Directly in Greenhouse Raised Beds - click here).
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| We're vegetarians and end up with a lot of
these white, plastic, square tofu containers. We've found they make
great tubs to start small seedlings. We drill holes in the bottom for
drainage and fill with a finely sifted, moist, organic potting mix. |
This method
presumes you have a greenhouse though it doesn't need to be
very big. Seedlings will need sun and protection from wind and severe
cold once they have germinated. In 2010, we started everything we
needed for three 50 x 50' garden-beds in an 8'x10' greenhouse (below). We just
had to time everything so that the first seedlings that were less
cold-sensitive (lettuce, peas, cabbage etc.) could be brought outside in
time for the hot-weather crops (tomatoes, peppers, melons etc.) to be
started inside.
Of course if you have a much larger greenhouse, you can start many more seedlings!
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| In 2010 we started everything we
needed for three 50 x 50' garden-beds in this cozy, little 8'x10' greenhouse. We just
had to time everything so that the first seedlings that were less
cold-sensitive (lettuce, peas, cabbage etc.) could be brought outside in
time for the hot-weather crops (tomatoes, peppers, melons etc.) to be
started inside. |
First
step - Soil: In the early days of the Sharing Gardens we purchased
soil
by the trailer-load. We chose an organic soil that didn't have any
nutrients added, and added an organic fertilizer. We mixed up batches in
a wheelbarrow. Later, once we were more established, we began to make
our own potting mix but most people don't have that capacity. Just
be
sure you use 'organic' potting mix from a reliable source.
Sifting Soil: The key here is that, if your potting mix has large
chunks of organic matter, your seedlings will struggle to grow.
We sift
our soil through a nursery flat with tiny holes to remove all large
chunks.
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| We use a nursery-flat to sift our potting mix. This gets rid of larger chunks of material that would make new seedlings struggle to grow. |
Be sure your soil is moist, but not wet. Fill with a good potting mix,
using the bottom of another tofu tub to pack the soil firmly and make a flat surface for the seeds. This is important as,
if the soil level is uneven you will get varying germination-times for your seedlings.
You want them all to come up at once.
Planting seeds:
After misting the soil so it is good and damp, we sprinkle the seeds
with our finger-tips trying to distribute them evenly and not too
thickly. If the are planted too densely, it's hard to tease them apart
when you transplant them to larger pots.
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| Seedlings germinating in re-purposed tofu containers. We try to sprinkle them evenly and not-too densely. |
Lastly we gently sprinkle a thin lay of cover soil over the seeds
and lightly mist to settle the seeds. They must be kept moist but not
overly wet or the seeds and starts may rot. Lettuce and brassica seeds germinate best
in a cool soil so you shouldn't need to put it on a heat mat or under a lamp to get it
to germinate. If you do apply bottom heat, check seedlings frequently so they don't dry out.
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| Chris and Donn transplanting seedlings into tofu containers; six to a 'pot'. |
When the seedlings are about 1/2" - 1" (2 cm) high, they are ready for
transplanting. We put ours in regular or "jumbo" six-packs, or in the
same tofu-containers (six to a container). We use a
basic, organic potting soil and add our own fertilizer. To each
wheelbarrow of soil we add about two cups of all-purpose organic
fertilizer and about a half-gallon of sifted rabbit manure. (
Note 2025:
We now make our own potting mix from the compost 'harvested' in our
greenhouse paths, wood-ash and perlite:
Making Your Own "Veganic" Potting Soil in Your Greenhouse Paths - Using Worms).
For the Sharing Gardens, where we might grow 1,000 or more lettuce
plants per season, transplanting is done in large batches.
Being
systematic in the nursery will save you time and materials and you will
have much better results. Have labels ready so you keep track of the
varieties you are transplanting.
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| Being
systematic in the nursery will save you time and materials and you will
have much better results. |
Fill a flat of six-packs (or tofu containers) with soil and mist them with water. Wet soil is less shocking to
transplanted roots than dry.
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| Adri, filling 6-packs with soil. A fun, relaxing job, at any age! |
Using your finger, a stick or some other object,
make a generous hole in
each of the cells of the six-packs (or whatever you're planting into).
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| Lettuce seedlings in a tofu container. Using a pen to make holes for transplants. |
To remove seedlings for transplanting: Cupping your hand over the whole tofu-tub
of seedlings, flip it over and tap the bottom, catching the whole clump
of soil and seedlings in your hand. Gently flip it back over and place
it on a tray to catch the loose soil as it drops off.
From the tray, pull off a clump of seedlings and,
holding them by their leaves, tease apart a single plant with its roots.
It is very important that all the roots go down
into the soil and are covered. If they stick out from the surface, this
is called 'J-rooting' and will often kill the plants as they dry out
too easily. This is why you want to dig a generously-sized hole so the
rootlets don't catch on the sides as you lower them in. After pressing
the soil in around each seedling, water them in gently to settle the
soil. Label the tray and move onto the next.
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| Transplanting seedlings. Note: Hold seedlings by leaves, not roots or stems. |
Depending on warmth and sunlight, and the size of the six-packs you use,
your lettuce will be ready to plant in garden beds in six to ten weeks. If
you
stagger your plantings it will mean your lettuce doesn't all come
ripe at once. Ideally you
wait until the root ball has filled the
six-pack cell enough to hold the soil as you pop it out, without being totally root-bound
(roots coming through the bottom of the six-pack).
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| A variety of seedlings growing in tofu containers; six to a pot. |
A week or two before
you transplant into your garden, bring the starts outside and begin
"hardening them off". Put them where they will get plenty of sun but not
too much wind. They will withstand a light frost but if it is going to
get very cold, or doesn't warm up in the day, bring them back
into the greenhouse till conditions improve. During this hardening-off
period, prepare garden beds so they are ready to receive transplants. In
our "deep-mulch/minimal till" gardens, we pull a row of mulch over to
the adjacent path (with a pitchfork) and, with a trowel dig a small hole
just the size of the lettuce's root-ball. This leaves worm holes intact
and lettuce seems to thrive without any roto-tilling needed.
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| Seedlings "hardening-off". |
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| Transplanting peas and lettuce |
We don't find that additional fertilizing is necessary for
lettuce
plants. They receive enough nutrients from the soil. But heavy feeders
such as broccoli, cabbage or any of the other
'brassicas' would benefit from added compost or some organic fertilizer
mixed in at the site you are planting out your seedlings - just don't
use too much or the plants will grow quickly and have thin cell walls
making them more susceptible to pests.)
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| Several weeks after transplanting. Picking individual lettuce leaves for salad. |
We hold off on
mulching them because we want the sun to warm up and dry out the soil
and mulch provides habitat for the
slugs. Sometimes, after the lettuce or other seedlings
are well established and the soil is warmed up, we mulch with a few
inches of grass clippings around our plants. Ideally, let the clippings dry out
for a few days on a tarp or in a bin. Fresh clippings, if piled thickly,
can heat up considerably and burn your plants.
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| Chris Burns with beautiful lettuce harvest! 2011 |
We plant our lettuce spaced about 6" - 8" (12 - 15 cm) apart (brassicas need more room: 18" seems to work well...). We
harvest
the lettuce intermittently, giving the remaining lettuce room to grow. In the
early stages, before the heads are fully formed,
we harvest one to three
leaves off each plant, rather than clipping whole heads.
As the heads
become full-size we harvest by cutting them off at the root with a
paring knife, leaving the roots in the ground to feed the worms.
We
hope this post has helped take some of the mystery out of starting
spring crops from seed. If you've been interested in learning to
save
your own seed, lettuce is one of the easier crops to save seeds from.
Here's a post we wrote about the process:
LINK: How to Save Your Own Lettuce Seed Enjoy!
ONIONS: Some years we have better success than others in growing onions. With gardening, there are always so many variables so, what works one year, may not work the next! Here are posts that outline the methods that have yielded the best results over many seasons:
