Best Tips for Starting Seeds Indoors

Over the years, I’ve had lots of successes and lots of failures with indoor seed starting. While seed-starting time is in February or March in many parts of the country, early April is actually a really good time to start seeds indoors in Minnesota, especially if you are planning to grow warm season crops such as tomatoes.

So, here are my top six tips for starting seeds indoors successfully.

seedlingNo. 1 — Put them where you will see them. Many gardeners have to put their seed-starting set up in the basement. They end up forgetting to check them and before you know it, the seeds are dried up or overgrown. Put them in a prominent place so you are inclined to coddle them.

No. 2 — Let the breezes blow. Outdoors, your little seedlings will experience wind (where I live, it’s gale-force a lot of the time), so get them used to it with a fan set up near your seed starting area. Keep the fan on low to get the seedlings used to wind. This will also help reduce fungal diseases.

Tomato seeds planted and labeled.
Tomato seeds planted and labeled.

No. 3 — Label, label, label. You think you will not forget which of the six varieties of tomato seeds you started are in which pots — but you will. My latest trick is to use a label maker to create labels on the seed starting trays. This is much neater than writing it out on a popsicle stick and less likely to fall off or get washed away. When the plants move to the hardening off stage, the label maker will be employed again.

No. 4 — Water gently and sparingly. More seedlings have been killed by drowning than by drying out. Water regularly, not too much, and if at all possible, from the bottom. My current set up includes really great trays I got when I ordered prairie plants from Prairie Moon Nursery. Each cell is 5 inches deep and the cell tray stands in another tray. I just pour the water into the lower tray and the plants drink it up from below. This encourages the roots to go deeper. When seed-starting season is over, I wash the trays thoroughly and give them a dip in a 10 percent bleach solution to kill any bacteria.

No. 5 — Don’t spend too much. If you only are growing a few tomatoes, it may not be worth your time and money to start from seeds. Just buy a few plants at a local farmers’ market or a garden club plant sale. You don’t need a fancy grow system either — a basic shop light, a couple of flourescent bulbs and a way to suspend the shop light above your seed trays, trays of some kind and seed starting mix — that’s all you need. Do buy or make your own seed starting mix rather than using old potting soil or garden soil.

No. 6 — Pot them up. Depending on the size of the cells you use to start your seeds, you may have to move them to larger pots as the plants get bigger. This is particularly true in my experience with those little pellets that expand when you add water. I’ve got some seedlings that were planted about two weeks ago that are going to need to go into a bigger pot very soon. Save small yogurt cups or the pots that purchased plants came in, add some potting soil and very gently move the seedlings into a bigger pot. Pot them up gradually. A tiny seedling might go to a 2-by-2-inch pot or a 3-by-3, even if it eventually will fill a large container.

For more information on seed starting:

Getting Ready for Seed Starting

Looking at a forecast that includes several days of 60 degree weather, in March, in Minnesota — well, it’s hard not to be thinking about seed starting. But hold off — this too may pass and, in fact, I’m hoping it does. A very early spring can wreck havoc on Minnesota’s outdoor plants as we found out in 2012 when an unreasonably warm March caused fruit trees and other plants to start acting like it was spring only to get zapped by a nasty freeze in April.

I organize seeds by whether I'm starting them indoors or out and on which day.
I organize seeds by whether I’m starting them indoors or out and on which day.

So, while this weather is tempting, stay off the grass and out of your gardens to avoid compacting the thawing earth, and think about indoor seed starting instead. I’m getting ready to start seeds in the next couple of weeks. I’ve checked my light set up to make sure it’s still working and organized my seed box so I know when to start what. This year I’ll be starting a few more annual flowers than I have in the past. I find the home-started annuals do just as well as those I’ve bought as starts and there is a big savings on costs.

This is not a cosmos I started from seed, or grew at all, but isn't it pretty?
This is not a cosmos I started from seed, or grew at all, but isn’t it pretty?

Most of them can be started about the same time as many of your vegetables. Here’s a typical schedule for starting annuals. The “last frost” date in Minnesota is typically in early to mid-May, so I use May 15 to be on the safe side.

8-10 weeks before last frost: Baby’s breath, viola, vinca, alyssum

6-8 weeks before last frost: Snapdragons, ageratum, gomphrena

4-6 weeks before last frost: Celosia, cosmos, sunflower, marigolds, salvia

This year, I’ll be starting baby’s breath, violas, cosmos, sunflowers, marigolds and salvias, in addition to a fair number of vegetables.

What plants will you be starting from seed this year?

Winter Sowing Native Plants, Two Ways

A week ago, we had a few days of pleasant 30-degree weather here in Minnesota, perfect weather for winter sowing native plants for the meadow I maintain behind my house. The meadow has been challenging, to say the least. There is a lot of weed pressure near it (and in it). It’s been one of those garden projects that reminds you just how small and ineffective you are compared to Nature, with a capital N.

So, I was thrilled to see that Prairie Moon Nursery, where I bought most of the plants and seeds I’ve used in the meadow, was offering a Jungle Prairie Mix of seeds. According to Prairie Moon, the Jungle Mix  “includes the most robust and competitive prairie plants available. The Jungle Prairie is perfect for a weedy ditch, a privacy screen, or for just establishing a profusion of flowers while providing habitat for wildlife.” Sounds good to me.

Seeds waiting for spring
Seeds waiting for spring

I ordered enough seeds for 2,000 square feet to spread on the meadow. I also liked that this is a project they recommend you do during winter — a time when I’m less busy in the garden anyway. (Prairie plants tend to need stratification to germinate — that is, the process of breaking the seed coat by repeated freezing and thawing — so sowing them in winter allows the process to happen naturally.)

The directions for spreading the seeds call for dividing your area into smaller spaces so that the seeds are more evenly spread. I visually divided the meadow in four, then mixed one-quarter of the seeds with a filler material and spread it on each section by tossing it as evenly as I could. My husband raised the issue that birds would eat the seed, but we did not see any increase in bird activity after casting the seeds. We have a feeder not too far from the meadow, so hopefully they will get their sustenance there.

While working on that type of winter sowing, I dug out some of my seeds from last year. I found several kinds of seeds that work well in the meadow—lupine, prairie coreopsis, rose milkweed, and asters, among others—and decided to sow them in traditional winter sowing containers. That way I can place them in the meadow, where I think they will look best. (Read the first paragraph of this post again and ask yourself: Why is it so hard to let go of control?)

Anyway, I have complete instructions on winter sowing in containers on the blog and followed them, using a fairly light potting mix, which included potting soil, perlite and vermiculite. Three of the winter sowing boxes are outside now and more will be added as we empty lettuce containers and milk jugs here.

Will you be winter sowing this year?


Update on the Winter Sowing Containers

winter sowing containers
Lots of germination; lots of rain.

I wrote some time ago about starting native perennials in winter sowing containers, and thought now would be a good time for an update.

Given our horrifically long winter, the plants in the containers are still pretty small. The good news is, germination occurred in almost all of the 28 containers. The two that have not germinated yet — and I do not expect them to — got pretty water-logged and the seeds may have rotted.

Because of the long winter, I did not end up following the usual winter sowing procedure. Normally, winter-sowers will put their plants out sometime during the winter and leave them there until it starts to warm up. Gradually, they will open the containers up, closing them at night to keep the plants warm. Minnesota springs are not usually gradual and this one was light-speed. On May 2, we had about 10 inches of snow on my garden and a temperature around 28. On May 14, the temperature flirted with 95. (Are we crazy to live in this climate? Very likely.) In any case, once it started to warm up, I just took the covers off of the winter sowing containers and called it a day. Of course, since then, it has been cooler, grayer and pretty wet.

I’ll let the plants get up to size and then, over time, transplant them out to the meadow where they will add color to the grasses and other plants I purchased from Prairie Moon Nursery.

My experiences with winter sowing have always been mixed. It does work — no question about it — but it does not work as well as starting plants under lights. It’s great for a situation like this one: I want a lot of plants and I want them cheaply.

What’s been your experience with winter sowing?



How to Build a Garden Low Tunnel (for Free)

low tunnel complete
Low tunnel ready to protect plants from endless winter.

Like many Minnesota gardeners, I’m getting itchy to put some plants in the soil. I have lettuces and greens under lights in the basement and some tomato seeds planted, but not yet germinated, in a warmer spot upstairs, but that’s not the same. It’s still pretty cold here and as I write this post on Friday afternoon it is snowing. Ugh.

Given the rather gloomy forecast, I decided to take things into my own hands and build a low tunnel where I could plant out greens and keep some of the seedlings as they get growing. I’ve been reading a lot about season extenders in the past year or so. We had a great article by Colleen Vanderlinden on them in the September/October issue of Northern Gardener and I recently read with enthusiasm Barbara Damrosch and Eliot Coleman’s new book The Four Season Garden Cookbook, which includes lots of practical tips on using cold frames, movable greenhouses and low and high tunnels to grow food in colder climates.

One of the designs involved using welded wire fencing and plastic. I had both on hand and knew I could fashion something serviceable pretty easily.

plastic ties
To make a longer tunnel frame, I joined two sections of fencing with plastic zip ties.

Here’s what I did: I took a length of 4-foot tall welded wire fencing and cut it in two equal pieces using a bolt cutter, making the cut in the middle of a square so that each end had a little tail on it. (Careful, these are sharp.) The raised bed I have the tunnel over is about 3 feet wide by 8 feet long, and the two welded wire pieces were about 4 1/2 feet across — just enough to create a bend for the greenhouse effect. I joined the two pieces to form one long one using plastic zip ties.

Next, I laid a painting drop cloth on the floor of the garage and put the wire tunnel on top of it. (If you have a heavier grade of plastic sheeting, use that.) I pulled the sides up and attached the cloth by poking the wire tails through the plastic. I left as much plastic as I could on each end of the tunnel and on the sides. I plopped it on the bed.

tunnel in plastic
Sheathed in plastic, the tunnel is ready to go to the garden.

Now came the tricky part. We live in an area that is really, really windy, and I knew I would have a flying low tunnel if it was not secured. I ended up doing two things. On each end of the tunnel I placed a piece of 2-by-10 lumber about 3 feet long. (I happened to have these on hand from another project.) Then, I took some rope and lashed the plastic down in three places, tying the ends of the rope to some winter-sowing jugs. Any fairly heavy plastic jug with a handle to tie the rope to would work. Voila!

The tunnel stood up to a fairly stiff breeze last night with no problems. I’ll start planting seeds and putting out seedlings on Sunday, when the weather is predicted to be a bit warmer.

It’s rare that I have all the equipment on hand for a project like this but this time I did.  There are many videos on youtube about hoophouses and tunnels. While the production quality isn’t great, this one has good step-by-step information on how to put together a low tunnel using PVC pipe and plastic.


Catalogs vs. Online Seed Shopping

old seed catalog
This is the catalog one of several seed companies once based in Minnesota.

Within a week or two, the pile of seed catalogs next to my reading chair will be just about to topple over. It’s that time of year—and I love it. Though I’m not a complete Luddite and do much of my work online (ahem, this is a blog), seed ordering seems to require paper and pens.

The reasons I prefer to choose seeds using catalogs are many: the comfort of being able to page through multiple catalogs at once; the feel of the catalog paper and the chance to peruse gardening information without having a hot laptop on my thighs, savoring the images and the descriptions of beans, potatoes and melons that would make a poet swoon, plus I have my special seed ordering system.

Here’s how it works: I wait until mid-January or beyond to even look at the catalogs, just letting them pile up as the anticipation builds. Then some evening—after the Christmas decorations have been removed and preferably with snow falling—I start reading. At my left is a cup of tea and a red pen. On the first pass through the catalogs, I circle all the seeds that appeal to me and rip out the pages on which they are listed. No judgements, just what looks good. In one evening (sometimes two), I’ll have a pile of torn pages and a pile of tattered catalogs.

Of course, my eyes are always bigger than my time, my garden and my skill, so I need to restrain myself. What do I really want to grow and eat? What kinds of annuals do I want to grace my front walk? What will work in my soil and sun and climate? What old faithfuls must I plant and which new things do I want to try? There will be lists and sometimes maps of the garden space. This is—as my father once said about waxing a car—contemplative work. No need to rush.

When the list has been narrowed, it’s time to get practical. I don’t like to order from too many companies, and I have my favorites in terms of quality and customer service. But I usually order from at least three companies. When all the decisions have been made, I rev up the laptop and do my ordering. With the catalog pages at hand, it’s easy to finish this step quickly. Some seed companies do not have catalogs because of the cost involved in printing. I understand that, and if I am looking for a specific seed, I may check out these sites. But still, I hope companies will continue to produce catalogs.

My winter evenings would not be the same without them.


Hardening Off: Seedlings on Wheels

Ready to roll back into the house!

I haven’t written much about seed starting this spring, because I’ve cut back on the number of plants I’m starting. After several years of seed-starting efforts, I’ve figured out that I do best starting tomatoes, Yvonne’s giant salvia and maybe a few brassicas (this year, Chinese cabbage and broccoli Romanesco). The brassicas are in the garden already, but the rest of the plants are still on my seed-starting shelf — which is a cheap metal shelf unit from which hang shop lights with fluorescent bulbs.

The seedlings started in the basement, but I was neglecting them, so I moved the shelf up to my office, which is now on our first floor. During the move, an inspiration struck — put the shelf on wheels! A quick trip to the local hardware store got me the wheels I needed, and today I wheeled the seedling cart from the office out to the deck for a couple of hours of fresh air. So easy! So quick! This might make hardening off, which I normally consider a huge pain, fun.

Hardening off means gradually acclimating seedlings to the outdoors. It is best done over a couple of weeks. (Northern Gardener has a good article by Colleen Vanderlinden on how-to harden off in the March/April issue.) I tend to rush the process because it’s such a pain moving all the plants in and out. With the wheeled cart, I can easily bring the plants out or in, depending on the weather and the sun. Hopefully, this will mean stronger plants when the time to put them in the ground comes.

Winter Sowing Tomatoes

Just waiting for spring.

I’ve used the winter-sowing method for starting perennials from seed ever since Northern Gardener ran Michelle Mero Riedel’s article about the success she has had with the method. Briefly, winter sowing involves planting seeds in damp potting soil in mini-greenhouses, mostly using clear gallon milk jugs. You set the containers outside any time in winter and in spring they sprout. This website has a detailed description of the process.

My results have never been as good as Michelle’s. But, the method does work, and this year I decided to try it with tomatoes. Like many gardeners, I often find tomato “volunteers” in spots where I grew tomatoes the previous year. So there’s no question the seeds can stand up to winter here. I’m starting more annuals from seed this year, so my light stand is getting full already. Last night, I collected my containers, dampened the seed starting/potting soil mix, and planted three kinds of cherry tomatoes: Austin’s Red pear, Sugar Sweetie, and a red and yellow mix. I also planted a container of a new morning glory mix that I’m trying.

The containers have joined those planted with lupines, coneflower and other perennials that I know respond well to winter sowing. With the warm weather coming this week, I’m hoping it won’t be too long before we have seedlings.

We Have Seedlings!

lupine seedling
They're HEE-RE!

What’s more exciting than seeing the first seeds sprout for a new garden year? Yesterday, I noticed that the lupine (‘Russell Blend’) seeds I planted a few weeks ago are now sprouting. These required a cold treatment in the garage for a couple of weeks. They have been under the lights in my basement for about a week. Some seeds for pansies (‘Swiss Giant Blend’ and ‘Got the Blues’) have also sprouted. Woo-hoo!


Seed Starting, Inside and Out

It’s still a bit early for starting seeds indoors in the North, but I’ve been getting ready for it and setting out several winter-sowing containers. You’ll find a new how-to page on indoor seed starting on the header above, which gives the basics and a few tips based on good experiences (and bad ones) that I’ve had.

Winter sowing containers

A couple of years ago, Northern Gardener ran an article by Michelle Mero Riedel on a seed starting technique called “winter sowing.” It was probably the most popular article we have run in the past five years. Basically, winter sowing is a way to start seeds outdoors.

Don't forget to mark the containers!

Here’s how you do it: Collect a bunch of clear plastic containers. Michelle often uses clear 1 gallon milk jugs, but they don’t carry those in my stores, so I like the larger plastic containers that salad greens come in. You clean the containers, poke holes in the bottom and top, and fill them with 2-4 inches of very moist seed-starting mixture. Then plant your seeds and put the containers outdoors. Tip: Be sure to write what you have planted in the container in a permanent marker inside the container. That’s all you do until spring.

Come spring, you’ll start to see little seedlings in the containers. At that point, you’ll want to poke more holes or open the containers up a bit during the day to keep the plants from over-heating.  When the temperatures are warm enough, you just plant the seedlings in your garden or containers as you would any other plant starts.

Winter sowing works best for hardy perennials, I think, but some people use this method to start tomatoes and other plants. Since I have a meadow area that I plant out, I use winter sowing for additional plants for the meadow. This year, I started two kinds of lupines, a native coneflower (Rudbeckia laciniata) and tall rudbeckia (Rudbeckia hirta). These all do really well in winter sowing containers.

For a demonstration on how to set up your winter sowing containers, check out Terry Yockey’s video. There’s an organization for winter sowers, as well, at this web site.