Very nice design. Thanks.

Nice presentation and nice items. I may have to build both. Thanks. Carol

Hi, I like it. I like the idea of having it off the ground like that so you get easier access to it. Nice barn too. It looks like it has a lot of history. I keep on starting seeds inside on the window sill or under grow lights and then having to harden to outside conditions. The simplest designs are always the best. I have to put that on my projects list.

Really great design. Thanks for sharing!

Thanks to all for the compliments. Yes, having it off the ground is very helpful for tending to the plants as well as lifting the flats in and out. My back is not so good any more so most of my designs take this fact into account.

A quick response to some questions folks have been asking me:

I have some leg designs that could be used in lieu of the garden benches that I will pass on to anyone interested.

This grow box could easily be constructed as a permanent fixture if so desired, but cedar or treated lumber should then be used as well as UV protected greenhouse-grade plastic or better yet twin wall polycarbonate for the windows. I have been using plain 3 or 4 mil plastic sheeting and it slowly degrades and becomes brittle with age. Because the units are stored indoors most of the year I have been able to get 6-7 years of life before having to replace the plastic. I plan to replace once and for all with polycarbonate sheeting which would also add a bit more structural rigidity to the windows.

The direction that the windows open could easily be switched by simply hinging them on the back instead of the front. I recommend some kind of small anchor chain or rope be attached from the base to the windows to keep wind from catching the windows and flipping them all the way open, possibly damaging them or ripping them off the base.

The box could also be constructed using lighter weight materials but then winds could become a serious issue and possibly blow over the entire unit, especially when the box is standing empty.

-Tom

What months is that unit in use?

Dan

Dan,

I usually set the first unit up in the third or fourth week in March. The second unit is needed for overflow for when I start transplanting seedlings into larger pots, and is usually set up in the middle of April. Both boxes are in use through May and are usually disassembled and put back in storage by the middle of June.

Minnesota has a wildly fluctuating spring climate. I learned a long time ago it is just not worth it to take risks by planting out flower and vegetable starts too early. In my zone I plant tender flowers no earlier than May 15 and tomatoes, peppers, eggplant no earlier than June 01.

The boxes have been a very good solution to late frosts and have saved my "crops" several times, while neighbors unfortunately had planted out their tender flowers and vegetables then lost them to the cold (I usually then give them a bunch of my plants to replace what they lost in return for a few good natured I-Told-You-So's). I have an older photo somewhere of the boxes full of transplants with 2 inches of snow on the windows. That year we had snow on the Memorial Day weekend and I ended up putting a small circulating fan heater in each box and covered both boxes with old blankets. The plants came through ok.

I do not want to deal with the worry anymore so now if it is going to get too cold I simply unload the boxes and stack the flats indoors on shelves - in an emergency situation like that I have found that plants can take a few days without sunlight. Of course the plants then need to be reintroduced to full sun carefully for a few days.

-Tom

Tom, I grow year round in Denver area, Z5b and my coldframes are in the ground, was wondering how well the box insulated standing in the free air. I like the portability issue very much, thank you.

Dan

Box insulation properties are poor but irrelevant for its intended purpose.

I consider this design to have two very narrow functions. The first function is to reduce the use of my light shelves and save money by having young seedlings outside in a sheltered, full sun environment when possible (which is better for them anyway). The second function is to grow and acclimate up-potted seedlings until conditions are right to transplant them outside. When cold snaps occur all the plants are brought indoors for protection.

For example, at the time of writing this the weather here has been unseasonably TERRIBLE (cold, cloudy, snow/rain for over a week now). The box has sat empty and unused for 7 days. All the plants have been kept under lights. Usually by this time of year the weather is good enough to start keeping the transplants out in the grow box 24/7.

I have cold frames in the ground as well and use them to grow very early crops of lettuce, radish, spinach, etc. - they serve a completely different function for me in spring and fall.

I guess that is why I prefer to call them "grow boxes" rather than "cold frames" but some people disagree with me as to the proper terminology. Ultimately irrelevant but I always include both terms to keep the peace. :-)

-Tom

Tom,
I'm interested in pictures or building directions you might have for your "grow boxes" if any are available. Thanks

vermontkingdom - I can put together some dimensioned plans for you. Please send me an email telling me whether you intend to construct a knock-down or a permanent structure, and whether you want me to include plans for a leg system. I will need your email address anyway so I can send you the plans and lists when completed.

I will try my best to include everything needed - dimensioned drawings, construction steps, material list, tool list, etc. Not that complicated - been wanting to do it anyway.

I have some downtime this weekend so I can probably have everything done by Sunday evening (mid-week at the absolute latest if something interferes with my schedule).

-Tom

Very nice! I have started growing from seed this year but I am doing the springsowing instead of indoors. I am doing pretty good so far. I have about 5 flats of petunia so far. And various veggies. I really like doing it outdoors but with this random weather this year I was hoping to use a cold frame type box to make it easier to protect from wind and snow. Currently I have a thin plastic "tent" with holes in it for rain to get in. The seeds started just fine this way so do you think I could start them in this? With the lid down would it hold enough moisture in? Then once sprouted and the lid is up how often do you water them?

This would be so much easier then having to cover and under with a tarp everynight....Then in June I would put it away.

Every year I buy about 15 flats of petunias from a big box store and I just cant afford it anymore. I need something that can handle mass production like this.

crazyutahn,

I think your idea might work with my grow box concept but at this point you have more experience growing from seed in flats outdoors than I do.

The box holds moisture in o.k. but it is not sealed in any way so one should expect to water flats on a daily or every other day schedule. It could be sealed quite easily but then one raises the risk of disease. Soil moisture retention in the flats will vary based what size cells are being used and based on the weather - the soil will dry out faster on warm, sunny days than cold, cloudy days. I have gone as long as 5 days without having to water plants but I would prefer the sunny days for the plants and if I have to water every day because of the wonderful sunny days then so be it.

I inspect plants every day and water accordingly. There is no set schedule and water need will even vary from pot to pot. The lids are positioned daily based on the weather. Cold, cloudy weather they stay completely closed. Cold sunny weather they are opened to the low position. Warm, sunny weather they are opened to the high position. I rarely open the lids completely onto their leg stands. The lids are always closed and locked down every night in case a storm blows up.

I hear you about the cost of purchasing large quantities of flats of plants. And I think they will be even more expensive this year due to fuel costs. That is why I originally built the boxes. I am inherently a cheap person and I refuse to consider purchasing all the plants that I need every year but I could justify the investment I made to grow quantities cheaply myself.

At this point I have both of my boxes set up and my up-potted seedlings have almost filled them up. I am still in the process of transplanting seedlings from the 1020 flats to 12 oz. Solo-type plastic cups. To date I have up-potted 250 individual tomato plants, 200 individual sweet and hot pepper plants, 350 individual petunias of 5 varieties, 400 individual impatiens, 100 individual begonias, 50 seed geraniums, and hundreds of miscellaneous flowers and herbs. No way I could ever justify purchasing these quantities - not to mention the varieties I grow that can not be found at any nurseries. To get these plants my expenses have been electricity (biggest expense), potting soil, and a few varieties of seeds (most seed is my saved seed, some from online trades).

I am going to make an effort to arrive at some kind of estimate regarding my costs per plant and will post that information. My guess is around 10 cents per plant at the high end.

I wish you the best of luck. Let me know what you decided to do and how it works out for you.

-Tom

Tom,
Thank you for the response. I think my husband has a new project. :) I will have to just keep a close eye on the mositure levels I think. On warmer days now I have a timer attached to my garden hose that I set to come on at noon for 2 minutes and then when I get home from work I water as needed. So with the lid open for air the timer will help keep them watered. And at night when temps get below 35 or a nasty wind snow storm I will not have to gather tarps from everywhere I just close the lid. I think this will make my spring sowing so much easier. And I will be able to grow such a better variety of annual flowers.I'm so excited I am going to start buying seeds now for next year!

I cannot believe you grow that much stuff!! WOW! That is inspiring to me.

Thanks again for the words of advise.

Tom,

a question from a newbie, i fancy one cold frame but wondering whether i can use a plastic box instead. Hear me out, I just moved house and i used translucent plastic boxes to move stuff, now it is empty and i bet sunlight can somewhat penetrate to the plants inside, so it'll be cold frame/cloche.. 2in1 kinda thing..
it's light, portable so that i can bring it inside at night, no sure about insulation, the lid can come off easily in regards to air circulation, and should be easy to clean.

I'm currently growing asian greens seedlings and the weather has not been sunny in Melbourne, australia at all (currently autumn and heading for a cold winter). i'm hoping i can get away with using cold frame/cloche for this coming winter. what do you think? is it do-able or i should probably get proper cold frame instead of the plastic box?

THANKS!

ps: am growing it in pots since the house is a rental and waiting for landlord's permission to grow on his backyard would probably mean i am wasting more time.

hungry_bunny,

I respect that you want to repurpose those plastic containers. It is good to recycle by reusing, not to mention that we gardeners are very good at improvising, making do with what we have, and dealing with the gardening situation we are currently in.

Will they work? Probably / Possibly / Maybe. I think it is certainly an interesting idea but they must be of a fairly small size being that they can be carried. The problem with a small size is that you will be dealing with wild temperature swings inside the boxes with the lids closed. If it is cloudy and cold outside and you have the covers on, and then the sun comes out, the plants could easily cook inside the boxes if you forget to open the covers. There are automatic openers available but I think their cost is hardly justifiable for this application.

There are probably others on GW who would have more experience with your concept. Maybe search the forums for similar discussions and talk to those folks. Or post the question in its own thread and see what others have to say.

What I would certainly recommend is to give it a try as an experiment, if nothing else. See if it works, and then post what you have done along with what worked, what didn't work, and what should be improved (if anything). There are lots of people in a similar living situation as you (renters, apartment dwellers, etc.) and I bet they would use your idea if it worked well.

Good luck!
-Tom

P.S. My latest photos (click on them to see full size):

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Photos taken May 26. Planted 200 impatiens, 150 petunias, 50 begonias, 50 geraniums into gardens, hanging baskets, and planter boxes and barrels on May 27/28.

I LOVE the design!! Thanks so much for sharing the photos!

I found the final not-yet-used space in my small yard and thought - cold frame!!

Today, I purchased reclaimed building materials -
what I think is redwood:
42 l.f. of 7.5"x3" planks - amazingly heavy and not like they sell nowadays
20 l.f 2x4"

what I think is cedar:
20 l.f. of 7"x1"

2 wood windows: 26"x31" ($2 each!!)
all for $53!!

The design I am imagining is very similar to yours, except that I want it on the ground and not necessarily movable.

Except for sawing, (terrified to lose fingers - so DH will be in charge of running the saw), I plan to build this with my son.

I had not thought of placing the hinges in the front and it makes total sense!!

THANKS again!!

Tom can you send me a email I have a few questions about build a coldframe and using it in west central mn thanks

I realize your post is old but I wanted to say that it has been very inspirational & helpful to me. I just added my first cold frame this spring & the information you have shared with us here has been such a help.
To see how productive your grow boxes are to you has answered many questions I had on how to utilize these structures in a way outside of just extending the season on cold hardy vegetables.
Thank You. Your photos on Flickr are just an added bonus to this post.
I'm sure my gardens will benefit from your knowledge.
I hope you're gardening successes continue in 2012 & into the future.
KanuK

Thanks KanuK - I appreciate you reply. Glad I could be of assistance and I wish you success with your efforts as well.

I am certain I disappointed a few folks last year by not replying to their requests for more information, and I sincerely apologize for not following through as promised. I have very little free time during the growing season and I have to prioritize, and some things just get dropped from my radar. I had kind of hoped that the pictures and picture notes would be enough info to get the "gist" of things - I wanted to show the grow boxes as a concept more than a gospel project consisting of cast-in-stone dimensions.

Was considering removing the photos but I guess I will leave them online for another year or so.

This year winter was so mild that I had the first box set up in early March and have been using it for some time now - saved a lot of money by not having to use artificial lighting indoors for starting seeds. I already have more plants than space - am already behind in setting up the second box. This year I did far fewer flower varieties and started 1000 impatiens instead. I am in the process of up-potting them right now, and the up-potted transplants will fill up an entire grow box.

Wishing a great gardening season to all.
-Tom

Tom
I'm sure fellow gardeners understand how busy we get once planting time draws nearer. After seeing the number of plants you propagate ... well I can't imagine how you found time to see my post!! but I'm glad you did.
My progression as a 'gardener' was nurtured here on GW & the addition of this cold frame seemed part of the process for me at this stage. My seed starting abilities are fine tuned now & my confidence in growing from seeds is established.
This year I want to propagate all of my annuals as I've become too penny pinching in my gardening ways to spend the money they ask for them. I think seeing/reading your process has encouraged me to venture forward.
Thanks again & I'd love to see some photos of your successes later in the season.
Bruce aka KanuK
PS...when's your last frost date? Mine is May 13th here in Zone 5 Quebec Canada

Just noticed that today is your birthday when I went to see your profile page.
Happy Birthday Tom!
Stop planting for the day & take some time to eat cake!

Thanks for the birthday wishes.

Yeah I always want to take pictures later during the season and I always put it off for tomorrow - then I never get around to taking them. Will have to try harder this year. I enjoy seeing other people's gardening photos as well so I urge all to post their gardening pics in whatever forum in which they may apply.

Regarding my system, the cost savings is really what my system is all about. As with you, I disliked spending so much money on plants every year and not having much selection to choose from regarding veggie starts, so that is what got me going. That and getting cabin fever so badly during winter that I get desperate to see something, anything growing.

Today is a good negative example of my system. The high is 39 degrees and it is cloudy so I only have cold-weather plants (cabbage family mainly and greens) out in the grow box. The impatiens and veggie starts are all under lights in my nice warm growing room. Plants go out or stay in depending on outside temperature and sunlight potential (which affects the potential temperature inside the grow box). It is a bit of a labor intensive system but by doing this I never really have to acclimate my plants. By late April, though, the plants end up outside in the growboxes 24/7 until they are planted in May.

I am zone 4b. My average last frost date is around May 10 - I always figure two weeks into May because it is easier to remember when doing my count-back regarding when to start certain seeds.

I up-potted 100 impatiens and quit for the day. Went out and did some dividing and transplanting of some perennial flowers until I got chilled. Harvested fresh asparagus, wild ramps, leaf lettuce, winter onions, green garlic, and fiddleheads for my annual charcoal and cherry wood-grilled free-range Black Angus porterhouse steak birthday dinner. Picked up a bottle of wine to round out the celebration. Life is good, despite the inclement weather. Only bummer is that the Morel harvest is still weeks away...

If the winds are blowing the right direction I may catch a whiff of that Porterhouse on your grill! Sounds like a great celebratory meal.

Our last frost dates are about the same. That makes me ask if you think it's too late to sow petunia seeds?
I saw your grow list for 2012. There you have a 'yet to do list' on which were petunias. The date on that thread was Mar.27.

Hope you enjoyed your evening.

PS weather is whacky everywhere. Today here was 82F. Way above seasonal.
Closed cold frame hit 125F ...no plants inside it..thank goodness.

I laughed at your rabbit story. Guess she thought the floppy lettuce leaves looked like other bunnies from a distance ... but had to eat lettuce when she found out otherwise. lol

Tom, this is brilliant! I'm hoping you're still occasionally checking this post because I'm also hoping you still have those plans that vermontkingdom requested back in 2011. Your knockdown design and the addition of legs to raise this up is exactly what I need. I've studied your pics but still can't figure out how you've fastened this together to be able to knockdown every year. I'm a relative newbie to this site (this is my first comment) and I'm not entirely sure how to send you an email, but if you still have those plans I'd be forever grateful if you'd be willing to share.

The file containing the leg design plans was lost when my last computer died. Contact me if you want to, I believe members have to "follow" another member to be able to contact. At least give it a try, anyway, see if it works.

-Tom

I noticed that the link to my grow box photo series no longer works, so I assume you have not been able to access them for viewing. Photo series explains in detail how everything goes together. Again, if you can figure out how to contact me, I will send you the link so you can access them. :-)

-Tom

Thanks Tom, I would love that link!

dentman4411, I would just love to see the boxes and get more information on them too. I read every comment and I sure wish this wonderful information was available. If you find a way to get to them, will I get a message about it? I don't really know this new forum yet. soilent_green, I would love to see your boxes. I really, really need them.