November 17, 2016

How to Grow Winter Crops in an Elevated Cedar Planter Box

Before you say "Matt, I though that you weren't going to write any sponsored posts?",  just hold on. Yes, my legal department would agree that this is indeed a sponsored post, but my content creation department says "hold on". You see - this is a product that I really use. And, it was I who contacted them. I have not problem when it is something that I really like. You probably already know that I use these 2 x 8 Elevated Cedar Planter Boxes but this time, I decided to actually contact the manufacturer and distributor - Gardeners Supple Company in Vermont. I told them my story - about how I saw that they were working with other influential bloggers, but that I felt that I really had a good reason why they should work with me - I already had three of them!

Much of what drove this post is that I discovered that they had introduced a new product as well - a cold frame top. If you remember, last winter I tried to construct a cover for my planter boxes using ridged poly from Home Depot, to craft a sort-of home made cold frame under which I could raised some winter greens, and a collection of precious Primula auricula, but  a cold frame top was something which I felt I could really test. Gardener's Supply agreed, and here I am.

There is no denying that these solid cedar hand made  Elevated Cedar Planter Boxes are built to last, but with the addition of a cold frame top, they are even more useful in extending ones growing season both in the spring and the autumn.

At roughly $350 (it depends on what you get for features, these beds may seem pricey to some, but their quality and design far make up for it. I assure you that you and your friends will be impressed. Their design alone is somewhat contemporary - straight lines, and no weird angles, they would look nice indoors if they didn't leak! As a gift, you might want to assemble first, and certainly, be sure to find the right site for it  - they will be heavy when full of soil.

Young plants of miniature lettuce (various gourmet varieties from Johnnys Selected Seeds.) These were sown in early September, and will mature through the early winter.

For three  few years I have been adding them to my garden one at a time. It's less painful that way, ad although I've been DIY'ing various trellis' and covers, on their website there are now all sorts of accessories you can buy. My old bedspring for a cucumber trellis wasn't really a good idea, visually. I really need this.

I know, it's messy, but we are in the middle of fall clean up. I wanted to show you that this one bed we set onto the deck, so that I can reach it from the kitchen door during the winter. On cloudy days, the lids remain closed.

Now, you might be thinking why do I need these? A guy with a greenhouse and a rather big garden. Sure, these are perfect for small back yards, older folks or for those who garden on rooftops, outside of apartment or condo gardeners, but I find them great for a number of reasons, and all are practical.

Napa Cabbage and Tatsoi almost ready to pick in this one Elevated Cedar Planter Box which was left open. Because you can plant thickly, and closer together, you can actually harvest more per square foot than in the open garden. Did I mention - no  bending over? I even can work on the bed from a stool. Like a little old man.

- Less bending over (I'm in the 50's, and although I still Cross-fit, any visit to the gym still gets me sore). Did I mention that I am a lazy gardener too?

- The dogs can't pees on the veggies. Pretty practical

- Few weeds, if any

-Healthy virus-free soil since I use a sterile compost

- Some crops simply perform better in raised beds, like tomatoes, cucumbers but I am pushing the limits here with cabbage and even flowers (flower farm in a box?)

- Critters like rabbits, mice, snakes and Irish Terriers who like to munch on Brussels sprouts and Chinese Cabbage so that they can fart all night, can't reach the crops.

This past spring, I raised Speckled Trout Back heirloom lettuce, a speckled Romain type.

On warm days, I can prop open the lids to allow cool air to enter.

This fall I am testing both the 2 x 8 elevated cedar planter box and the Grow House top or Cold Frame attachment, which is really what I wanted to play with. The Actual Grow House product looks interesting too, as the wood extends down to the bottom. Maybe I will save up and get one of those next year.

This fall I have planted a few crops in each of my elevated cedar planter boxes. I sowed 2 type of kale, one Russell Kale which I harvested as baby kale, and dinosaur kale, to get a jump on spring. I also sowed some viola and pansy seed. They have just been transplanted into the covered planter box, and I am looking forward to see how they survive through the winter. I expect that they will grow and bloom earlier than ones set out into the garden. Next fall, I plan on using this bed to keep alpine plants through the winter in.

Napa cabbage when it was first set out, in mid September.

It wasn't that long ago when retail garden centers didn't exist, and a farmer or a gardener had to raise their own seedlings or propagate their own crops. maybe seed saving is important to you, but for me, sourcing the varieties I want to grow requires much more work than picking up a pre-curated 4 inch Proven Winners at the nursery.

Here is a good example of miniature heads of lettuce, and standard-sized heads of heirloom Speckled Trout Back lettuce.

Most of plans for these elevated cedar planter boxes will be for summer crops, but I have a long list of projects that I am eager to try as well. Most of my ideas are inspired by classic gardening techniques only modernized for today's lifestyle and tools. I can imagine using the cold frame top as a stratification chamber for perennial seeds that I will sow in December from Jelitto seed (Anemone species, Delphinium, and Peony seeds), for alpine seeds from the NARGS, Scottish Rock Garden Club and AGS seed exchanges, for rooting evergreen cuttings and for keeping other plants that might need a bit of extra protection from only the most extreme temperatures - like scented violets. Viola odorata and Parma Violets were traditionally raised in cold frames in the North East.

Young Napa Cabbage are first sown into 2 inch pots in late August and then easily set into the raised beds, once the tomato plants are removed in late September.

I am already using one of mine for pansy seedlings, which were sown at the end of August, as well as for three varieties of dwarf lettuce and kale. I should mention that I feel that dwarf or miniature vegetables are best in these containers.

Baby lettuce will grow better with the onset of colder weather. In most years, I can harvest lettuce through the Holidays as long as it is covered with Remay fabric. I expect similar cold hardiness with the raised bed that is covered.

Selections and varieties bred for their small growth and space-saving qualities. But beware - even the 'dwarf zucchini' that I planted this summer taught me, even dwarf can be a relative term! Dwarf lettuce is a must - the tiny heads allow one to set 4 or five heads across, and an entire bed could be filled with a couple hundred plants. If you stagger the sowing, one can have fresh lettuce all winter long.

Young tatsoi when first planted.

I might overlook some crops however. You might want to be careful with crops which require you to harvest the entire bed at one time, such as spinach. It just does not make sense to me, as an entire bed would probably only produce enough spinach for one or two meals, and that isn't worth the time or space. But I highly recommend the sowing of mesclun, arugula, micro-greens, Asian greens and mini lettuce.

Young pansies which were also sown in late August, are also set into the new soil under the cold frame top.

As for assembling, these beds are easy to assemble, and they are solid wood. All you will need is a screw gun, a rubber mallet and some muscle. They come together in about an hour or less. Again, move them when they are empty!

The beds are designed for easy assembly. Screws are included and the legs are powder coated and very strong.

If you decide to get the cold frame top, the lids open with a very simple bar of wood, which easily adjust the height of the lids. It is a very simple design. If there is a downside (and I have not experienced this yet) is that when or if you want to remove the upper cold frame portion, some reviewers have said that it is difficult to slide off.  To avoid this, we used paraffin wax on the legs before inserting them. It seems to still be slick enough to remove, but I am not sure that I would ever want to remove it.

It can get a little tight when assembling some of the tooled parts, but everything fits nicely after some wiggling. An extra pair of hands will be helpful.

Once you have the top constructed, you will need to invest in good soil, and by good soil, I suggest a sterile professional mix such as ProMix or if you are peat adverse, a composted mix like BioComp. This may be the greatest challenge for some, but really, this is perhaps the single more important thing when it comes to raising plants. Do not garden loam, and be wary of Scott's or the commercial brands of potting soil, or any bag that is labelled 'top soil or garden loam. Peat may be unethical, but it is still the best growing material for raised beds. Pleas help me find something else, but I have never had luck with coir, and really - flying coir from South East Asia and thinking that you are saving your carbon footprint just doesn't add up for me.

Success is dependent on the site, and the soil. Don't skimp here, for good soil means everything.

Make your own compost with leaves, and add a lightener like Perlite, or go in for the ProMix.  Two bales of ProMixBX can run $75-$80 but it should last for about two years until you will need to replace it. Peat decomposes, and if you are planning on raising tomatoes, you will want to keep the soil free from disease.

These cold frames will work differently than those set into the ground, so some experimentation will be necessary, and you will obviously need to match whatever your crop requires. Generally, One wants to avoid  the cycle of freezing, thawing and refreezing, opting for a 'stay frozen, until spring comes' approach (for alpines and seeds) or 'keep just above freezing' (for winter greens).

To achieve this, once the temperatures begin to drop to 20 degrees or so, I may keep the lids cracked open just a bit. But I am not sure yet. It's not the cold which often ruins crops in cold frames, it's freeze-thaw, or heavy, wet snow and winter rain sitting on top of frozen soil.

The design here is simple. A twist, and the lids can remain open with just a wing nut and a piece of cedar. Good Yankee ingenuity.

Also, with the  real old glass light style 'on-the-ground' cold frames, Yankee New England farmers would have had to unroll quilts of hay (often sewn into a sort of quilted blanket) across glass which helped the structure retain solar warmth gathered from the day.  I doubt that the two wall plastic will achieve this, but it should reduce some heat loss for spring crops. It may do little for deep winter protection.

The best way to manage these beds through the autumn would be to keep the lids cracked open a bit, and then close then during the harsh, winter weather. In spring, you may need to open them in the morning, and the sun will becoming stronger in mid-February, but perhaps close them in the evening, depending on what you are growing. In the old days, life on a farm often evolved around letting the chickens and ducks into the coops at night, and shutting all of the cold frames. If I can do it, you can too.

Napa cabbage, almost ready to harvest. This is a mini variety called 'Minuet', but the are still larger than you might imagine.

Some radiant heat also began to extend the season from mid-February onwards if you beds are positioned where they will get winter sun.  Like my greenhouse, I looked for a spot where I knew
some sun would hit, even on the shortest day of the year in December. Some heat will be retained if sun is allowed to strike them on those short, dark days of winter but I also need to remain realistic.

I plan on getting more of these beds in the coming years, as I can imagine so many uses for them.

I highly recommend the Elevated Cedar Box. If you are interested, check out all of the different types and accessories at Gardeners Supply here


  1. Lots to think about here -- thanks. AND...Unlike in-ground planting or on-ground raised beds, above ground raised beds won't absorb moisture from the surrounding earth, and alpines and auriculas will stay drier at the roots. That means less freeze/thaw heaving and tearing of roots. Not to mention no slugs! ('RiverView' was from several years ago - it's Judy S. in reality.)

  2. Anonymous7:06 AM

    Wait, you're in your 50s? I've been following your blog for a while (I grew up in Hawaii, moved out East for college and stayed). With all you do, I figured you were much younger (in spirit, for sure). I'm also in my 50s with a partner of 27 years - retired in Southern Delaware after many years in the DC Metro area - now full time gardener. Keep up the good work - I really enjoy your blog. Rodney

  3. I have two of these, and the cold frame tops, as well. I don't garden in them over the full winter and so remove the cold frame top as the plastic lids will be damaged slowly with full sun exposure. (Confirmed in the information that comes with them.). I just wish they would offer covers for the beds, so one's soil (I use a very rich organic compost) isn't left bare all winter and leached of nutrients. Instead, I let the beds dry out to barely moist and cover them completely, including the cedar wood sides, with thick plastic. I'd much prefer a fitted cover with some arched infrastructure to allow rain and snow to slide off. Fingers crossed!

  4. When planting in raised beds, you might consider using worms. Yes, that's a real thing :) Consider making a vermicomposting bin with the so-called red worms. They break down organic matter into smaller pieces and this way make the beneficial fungi makes them available for the plants roots. As unpleasant as it sounds, it really works!

  5. Excellent post with good advice. As a designer, I have been getting many requests for raised garden and vegetable planters. They have been getting more popular as part of a garden room theme and homeowners find them easier to tend to and maintain.


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