Last updated on March 18th, 2012
WANT TO GET A JUMP-START on your veggies and flowering annuals (like the zinnia ‘Violet Queen’ above) without the fuss of fluorescent lights? Plant the seeds outdoors, in the same kind of miniature greenhouses used for winter-sowing. Outdoors, seeds won’t germinate as quickly as they would indoors under lights. But they will sprout earlier and more reliably than direct sowings made in the open garden. Here in zone 5-b, late March is the perfect time to plant the seeds:
Planted just last week in vented milk-jugs, my ‘Paris Island Romain’ lettuce (pictured above), ‘Bloomsdale Long-Standing’ spinach, and ‘Double Bon-Bon’ cosmos have already begun to grow.
And here are other flowers and veggies which lend themselves to “winter”-sowing in late March and early April:
Flowering Annuals (transplant to open garden after last frost unless otherwise noted)
Ageratum
Calendula (transplant after last heavy frost)
Morning Glories (soak seeds overnight)
Zinnias
Sweet Peas (soak seeds overnight)
Annual Asters (transplant after last heavy frost)
Sunflowers
Celosia
Nasturtiums
Marigolds
Vegetable Seeds (transplant to the open garden after the last heavy frost)
Peas
Spinach
Arugula
Kale
Lettuce
Chard
Beets
Onions
Broccoli
Leeks
Artichokes
Cauliflower
Brussels Sprouts
Other Vegetable Seeds (transplant to open garden after all danger of frost has past)
Eggplant
Tomatoes
Chiles
Sweet Peppers
Chives
Sage
Stevia
Thyme
Parsley
There is one caveat to early outdoor sowing. Although the seeds are somewhat protected in their vented containers, a sudden hard frost is likely to kill any which have sprouted. Therefore, keep an eye on the forecast! To protect seedlings on frosty nights, simply throw a blanket over the containers of sprouted annuals and veggies. (Thankfully, winter-sown perennials do not require protection from frost.)
Aside from their need for frost-protection, spring-planted vegetables and flowering annuals are treated in exactly the same manner as winter-sown perennials. Provide the seeds with constant moisture (if rainfall is not sufficient). Fertilize too, but only after seedlings have developed their second, or “true” set of leaves. Unhinge the covers of your containers on pleasantly warm days, and let the seedlings revel in fresh air. Replace the covers at dusk. To avoid overheating the seeds, set their containers in an eastern exposure that is protected from wind.
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Related Posts:
Seeds I’d Winter Sow: Bachelor’s Buttons
Seeds I’d Winter Sow: The Chocolate Flower
Winter-Sowing 101
How To Make a Miniature Greenhouse
Successful Seed-Starting Indoors
Justin says
Kevin, this looks like it is much easier to do than growing under lights.
I have a question, though. Do you think dwarf snapdragons could be sowed outdoors in containers now? Or is it too late?
Sheila says
Guess it's time to buy more milk…
Eric says
Kevin, this winter sowing (can we still call it that?) thing is really a blessing for the no-greenhouse and no-fluorescent lights gardener.
I've already started a number of seeds indoors under lights. But I'm going to start some of my later annuals outdoors, in milk jugs.
Kevin Lee Jacobs says
Justin – in zone 5-b, anyway, it's a little late to start snapdragons outside. While they would eventually germinate, they would not be ready to bloom, probably, until mid-summer. A better plan, for next year, is to winter-sow the seeds in in January.
Sheila – …or more gallon-size water jugs, and 2 litre soda bottles!
Eric – Good question! Although it's spring, I still call seed-planting in containers “winter-sowing” because the method is the same.
Sharon says
OK, I have a stupid question. All of my vegetable and herb seed packets say to plant the seeds AFTER danger of frost. Are you saying it's ok to plant them now?
Kevin Lee Jacobs says
Sharon – All questions are valid here!
When you sow seeds outdoors, in containers, you can ignore all of the information provided on seed envelopes.
Tender annuals — including herbs and veggies — can indeed be sown now. Once the seedlings emerge, it's easy enough to throw a blanket on the containers should frost threaten.
Andrew Thompson says
Kevin, I have a question regarding seed starting mixes. I've never had a problem with Miracle Gro seed starting mix. I couldn't find MG locally this year, however, so bought a large bag of Jiffy Mix for seeds. When I tried to wet the mix, water stayed on the surface. And when I tried to mix the water in, it turned to mud! Now I'm afraid to use it for seeds. Is Jiffy Mix…crap?
Kevin Lee Jacobs says
Andrew – Peat moss, if thoroughly dried out, will REPEL water. And therein lies the problem with your mix. Here's the cure:
Pour boiling water into the mix, and then reseal the bag. Permit the peat moss to absorb this liquid for several hours, and your mix will be much easier to work with.
Bob says
Hi Kevin,
Thank you for your newsletter. It's inspiring & empowering.
Thanks to your newsletter, this is the first year I am attempting winter-sow.
And it is the 3rd year, I'm attempting bachelor's button. I didn't have any luck last time ☹
It's my wife's favorite flower and this year I'm trying to surprise her.
I live in Montreal, zone 5, and from what I understand you live in the same zone.
You wrote that you winter-sow them in January, aren't they tender annuals?
Also, I want to plant
Anchusa, blue angel, Anagallis blue pimpernel, Nigella miss Jekyll and cynoglossum.
Is now too late or do I still have time for winter-sowing?
Kevin Lee Jacobs says
Welcome, Bob. Sounds like you and your wife like blue flowers as much as I do.
Since Bachelor's buttons, anagallis, nigella and cynoglossum all re-seed easily in zone 5, you can winter-sow them any time. My advice is to sow them now. We still have plenty of freezing nights ahead of us.
I hope you'll stay in touch. Feel free to ask any questions that arise. But I'm sure you'll have success with winter-sowing…the method really works.
Bob says
Thank you so much Kevin.
I have my jars ready, I'll plant them tomorrow 🙂
Yes we love blue flowers. From myosotis, Brunnera jack frost, Muscari and squills in Spring, Annual plumbago & cranesbill in summer & the perennial plumbago in late autumn, we love them all.
We also love blue/silver foliaged grasses and plant. You can say it is a sort of obsession 🙂
Thank you again so much for your blog.
It is a blessing to receive and read…
The Good Egg - Dianne says
I started seedlings inside (tomato, leek, peppers, lavender), but wonder whether these can be safely placed outside in containers such as you show now in April zone 6A? Would they be safe to leave outside to harden or is this best to have them start outside?
Kevin Lee Jacobs says
Dianne – All these seeds can be started outdoors now in mini-greenhouses. No problem moving lavender and leeks from indoors to out.
However,tomatoes and peppers will only germinate after the soil temp. reaches 70F or so. Consequently, if you want these seedlings soon, go ahead and start them indoors. Harden off outside when temperatures have warmed up.
Last year I started some tomatoes indoors, and some outside in milk-jugs. The outdoor-germinated seedlings were smaller than their indoor kin the first week in June. But by mid-month all were identical in stature.
Cecilie says
Hi, I hope this question isn’t redundant. I am in zone 7 (central Alabama) where winters are fairly mild with the occasional cold snaps. Do you have a formula for when you put things out? For instance a certain number of weeks before the last frost date or something equivalent that I could use to determine how I should figure out when to start seeds in the outdoor greenhouses here. I am mostly interested in vegetables and herbs. It’s late December here, so I’m wondering if I could plant things now and just cover them with a blanket if we got freezing weather occasionally? Thanks for any ideas you might have.
Kevin Lee Jacobs says
Hi Cecilie -You can winter-sow your all of your perennial herbs now. As for veggies, I’d sow the cool-season types. These include lettuce, spinach, peas, kale, broccoli. Hold off on the heat-lovers until mid-February or early March. No need to cover the mini greenhouses with a blanket during frost unless the heat-loving seeds have already sprouted. Perennial plants and cool-season veggies need no protection from frost. Hope this was helpful to you!
Heather Rogers says
Do you have a list of plants you would recommend using in Zone 8: Portland, OR?
Also, when would you recommend winter-sowing in this area?
Thank you so much! Love the blog, very helpful.