new light fixture purchased, new greenhouse structure assembled -- ready for transplanting

Today I purchased a new light fixture for the new greenhouse structure.  I decided on the 4' Quantum T5 Bad Boy with four bulbs.  There are four models of the Quantum T5 Bad Boy holding four, six, eight, or twelve T5 bulbs.  I was having trouble deciding how many bulbs I really needed in the fixture, and so I asked the sales clerk and he said that a general rule of thumb is 20W per square foot that you're trying to illuminate.  Since I'm hoping for the maximum illumination space in the new greenhouse to be 3'x5' = 15 sq ft, I figured I'd need a maximum of 300W, and probably much less, considering I wanted to have areas around the edges of the greenhouse that could count as partial shade.  This helped me to decide on the four-bulb fixture which supposedly supplies 216W, for $172.  The fixture did not come with bulbs, so for an additional $10 a piece, I purchased two grow and two bloom bulbs to try to provide the plants with something resembling full spectrum light. 

The bulbs are triphosphor coated and supposed to be higher output than typical T5 bulbs.  As you can read on the Harvest Moon website for the product (try to forgive them their typos), the Quantum Bad Boy supposedly drives its bulbs much harder than typical T5 fixtures, resulting in higher outputs.  I'm really more concerned with the efficiency of the bulb in terms of how well it lights the plants compared to how much it increases my electric bill, but maybe if it really is a higher output fixture then I won't have to have the lights on as long each day.

I also purchased and assembled another storage structure for the new greenhouse. 

As you can tell from the pictures, the new structure really dwarfs the old one.  It's large enough to house both the germinating trays on a single shelf and have a shelf for the larger plants as well.  It's 4' x 2' x 6', and I have divided the vertical space up into three shelves: one for storage and the electric heater, one for germinating, and one for the taller plants, measuring 11", 17" and 31", respectively.  Ultimately, I may put in some nice firm plastic for the walls, but for right now, I'm going to stick with the plastic sheeting.  I am however, planning on installing some fans for ventilation.  I'm assuming that the larger plants are going to need more air circulation than me blowing on them several times a day.  Tomorrow, the transplanting!   

long awaited temperature data: second shelf

Here is the data I took of the air temperature of the second shelf while the seedling heat mat was still in place.

The temperature and relative humidity measurements were made by the USB thermocouple every minute for almost two days.  During this time, the timer for the light fixtures was set such that the lights were on from 6AM - 12AM each day.  The heating from the lights is clearly evident in the graph.  This shelf is directly above the shelf containing the electric heater, which was set to maintain 80F by periodically pulsing on and blowing hot air with its fan.

The average temperature during the daytime was 76F and at night with the light fixtures off was 73F.  These temperatures themselves obviously aren't extreme, but considering that the second shelf also receives direct sun for most of the day on sunny days, and that the heat mat is supposed to raise the soil temperature 10-20F above the air temperature, I decided that the plants might be getting too warm.  To solve this potential problem, I unplugged the heat mat.  It doesn't seem to have had any adverse effects so far, and the new seeds I've planted have germinated just fine.

The large increases in relative humidity correspond to times when I watered the trays.  Generally, it's better to have a more humid environment when seeds are germinating and then maintain the greenhouse slightly drier when growing plants so as to decrease the likelihood of rot, mold, or pests.  The Greenhouse Gardener's Companion says that a relative humidity in the range of 45-60% is healthy for most plants, and that relative humidities greater than 80% foster rapid growth of leaf mold and other plant diseases and parasites. 

Since I took these data, I've added vents to the sides of the greenhouse.  I'm pretty sure the relative humidity since then has been much lower than that represented by this graph.  I've placed trays of water on all three shelves to try to help raise the humidity (and also to act as a thermal mass at night), but I definitely think that I'm still losing more humid air out of the slits than I'm gaining through evaporation, which isn't really surprising.  Most commercial and larger-scale greenhouses are able to vent air and maintain high relative humidities through the use of misting devices, but that's a little beyond the scope (and price range) of this first attempt at an indoor greenhouse. 

happy cilantro and transplanting soon

This morning I raised the light fixtures on both shelves again.  The general recommendation for mounting is ~3" above the tallest plants.  The tomato plants are growing taller and taller in spite of their discolored leaves and the purple opal basil seemed to be showing some signs of photobleaching, so I decided to raise up the fixtures another inch or so.

The cilantro on the shelf is doing fantastic.  I'm really pleased that this idea seems to be working out so well.

The Greenhouse Gardener's Companion says that it's generally a good idea to transplant seedlings from their tray to a larger pot when they have produced 3-4 leaves.  The garden sage, pimientos de padrón, basil, syriaca zaatar marjoram, cilantro, tarragon, and the tomatoes have all reached this point, so this weekend they will all get new larger pots.  This means I will also need to fashion a new greenhouse structure to contain these new pots and purchase the new light fixture that will illuminate them.  I'm really excited about transplanting the seedlings.  I like to think that a larger pot and fresh soil will do them all good.

more light isn't always better

When I returned from winter break, the plants were all healthy and green.  I took some really nice pictures of all the first primary leaves of the tomato plants and everything was really looking great.  I had been concerned over break, about the insufficient lighting for the two trays.  One, 2' T5 bulb per tray didn't really seem sufficient, and the phototropism in the plants along the edge of the tray clearly indicated a more uniform light source would be an improvement.

Phototropism of the Chadwick cherry tomatoes (tray 1):

My response to this phototropism was to add an extra 2' T5 bulb to each shelf, which was probably fine.  My mistake was in increasing the ontime of the fixtures at the same time.  The extra light combined with the extra exposure time seems to have primarily affected the tomato seedlings.  It's also possible that this was responsible in part for the yellowing of the cilantro leaves, but I think that the brown tips really indicated that they were being overwatered as well.  The tomatoes on the second tier slowly started to get yellow, dried out leaves.

Santiam tomatoes with signs of photobleaching (tray 2):

Somehow it didn't occur to me that this yellowing was due to the increased lighting and exposure time.  I was distracted by other potential weaknesses of the greenhouse, and thought that they could be the cause.  First, I thought that it was the lack of ventilation, and so I cut vents into the plastic sheeting on both shelves and made sure that the plastic sheeting behind the electric heater on the bottom shelf was open a little so that the fan would suck in fresh air when the heater turned on.  Then I thought that the tomato seedlings were getting too warm.  They still had the seedling heat mat under them heating the soil both day and night, and the lights kept the air and plants quite warm during the day.  So, I took another series of temperature measurements over the course of two and a half days (data forthcoming).  This confirmed my suspicion that, during the day at least, the air was getting quite warm (in the upper 80s F), and since the heat mat is supposed to raise the soil temperature by 10-20F above the ambient air, this seemed quite warm.  Just like with the addition of the vents, however, turning off the heat mat and raising the light fixtures, did not solve the problem of the yellowing leaves. 

Around the same time, the leaves on the tomato seedlings on the top tier also started to lose their green color, but instead of just yellowing, they started to look really dry and almost crumbly.

Crumbly, dry leaves on Fox cherry tomatoes (tray 1):

When I finally figured out that it could be photobleaching (which really should've occurred to me much sooner), I switched the light timer back to 15 hours per day and pulled the trays off to the side of the shelves so that they weren't receiving as much direct light.  I tried to let them recover in partial shade for a few days before I put them back fully under the lights.  This seems to have helped.  The green pigment is starting to return to the tomato plants on the second shelf, and most of the tomatoes on the first shelf no longer have crumbly leaves.

Improvement (tray 2):

My current thought is that at best I've just lost a month or so in plant growth, and that they'll eventually recover.  I probably need to thin them pretty soon, anyway, and that the stronger plants should hopefully survive.  It does seem strange to me that only the tomatoes and the cilantro seem to have been affected.  None of the other plants seem to be showing signs of photobleaching.

The worst case is that the plants never really recover and continue to have stagnant growth, never really putting out any more leaves until I finally give up on them.  I'm clearly hoping that this isn't the case.  I have started a few new Maglia Rosa cherry tomato seeds in the empty slots adjacent to the dill and tarragon in the second shelf tray as a sort of backup plan and to make use of the space that I'm heating and lighting 15 hours a day.  These have already started to sprout (quick, even without the heat mat).

Maglia Rosa cherry tomatoes (take two):

The cilantro by the window has also sprouted, though less vigorously than when in the greenhouse.

cilantro improved

The cilantro seems to have responded well to not being watered.  From Sunday morning until late Wednesday afternoon, I let the cilantro plants dry out.  Some of the wilted, brown leaves will probably never recover, but all of the plants have sprouted new leaves and are looking much better.

Day 48:

 

 

 

I'm currently watering them only every couple of days.  The stems seem floppy regardless, and I'm starting to think that they'd perhaps do best growing in a horizontal trellis for extra support.

As a result of the overall health of the cilantro plants, their sensitivity to heat, and the desire to have a constant supply of fresh cilantro, I've decided to start germinating a fresh batch of cilantro seeds outside of the greenhouse.

 
The Slow Bolt cilantro can supposedly germinate at temperatures much colder (55-65F) than the other plants I'm growing in the greenhouse.  So, I placed a handful of the seeds in organic seedling soil mix, watered the soil, and put the planter by a south-facing window.  I've covered the planter with a plastic container to keep in the moisture and allow the soil to retain at night some of the heat from the day.  With the larger planter I also can avoid the hassle of having to transplant them later.

sick cilantro, bolt, measuring second shelf temperature

I think I've been overwatering the cilantro.  The problem with an overwatered plant, is that except for the soil, it can look a lot like an underwatered plant, or an overheated plant.  Here's my wilty cilantro as of yesterday morning:

There are a lot of yellow leaves, some with brown edges, others with brown stems.  I had been erring on the side of overwatering the seedlings since I'd found some of the tomatoes looking particularly wilted after going more than 12 hours without water.  But I guess that was a few weeks ago, and it's probably time to start spacing out the waterings a little more.  I haven't watered the cilantro since yesterday morning, and am going to wait until at least tomorrow morning, even though the soil now looks quite dry.  Hopefully they'll be able to recover.

During my research into causes for droopy cilantro, I found out some interesting information about the plant.  I'd like to amend a previous post where I jokingly attributed the "Slow Bolt" name for the cilantro seeds I planted to a comparison between how long they germinated and how quickly they grew.  I now know that "bolt" actually refers to an herb sending up a flower stalk.  The flavor of the leaves often changes after it has flowered so bolting is undesirable, and the slower it happens, the better.  Cilantro in particular bolts due to temperature increase, typically when the soil temperature rises above 75F.  I didn't take that into consideration when I chose to plant it on the cooler top shelf and in a tray without a seedling mat, but it's good information regardless.  It also helps me rule out underheating as a cause for the wilting plants.

In other temperature related news, I'm starting to worry that the plants in the second shelf might be getting too warm.  They are closer to the electric heater meaning increased air temperature and are also on top of a seedling mat meaning further increased soil temperature.  I put the USB thermocouple on the second shelf yesterday evening, and am planning on letting it collect data until tomorrow night.  It will be interesting to compare these new data to those I collected previously from the top shelf.

future greenhouse plans, determinate vs indeterminate tomatoes

We've now had two consecutive sunny days here and it's been fantastic.  I don't know how much of the natural light is actually hitting the plants with the lighting fixtures in the way, but it's still nice to see the greenhouse lit up by the window.  The sunlight also helps heat the sunporch, which is always appreciated. 

I've been trying to plan out the next stage for the tomato and pepper plants.  In probably another month or so, they are going to be too tall for the current greenhouse structure.  There is only 15" of vertical space per shelf and the lighting fixtures themselves are ~2" tall.  This morning I raised the two fluorescent lights on the second shelf by around 2" to keep them from overheating the tomato seedlings that had grown up to meet them.  I could probably raise those lights another 4" and the top shelf fixture by ~5" before I'm out of room.  My current plan is to build a secondary structure that is actually more like a real greenhouse, and keep the current structure for germination and seedlings.  The new greenhouse will have only one shelf so that the plants will have less of a height restriction.  It needs to be at least 4.5' long and 2.5' deep in order to be able accommodate all of the tomato and pepper plants.  When the seedlings outgrow the germination trays, I'm planning on transplanting them into individual 3.5" (diameter) pots.  This new greenhouse should be able to hold over 130 such pots.  I only planted 96 total slots of tomato and pepper plant, which means that I should have plenty of space for the tomatoes, peppers, and some herbs.  I'm planning on switching to a 4' T-5 lighting fixture for this new space, but haven't yet decided how many bulbs I'll need.

One of the more interesting questions that I've been working on is which of the plants really need to go into the new greenhouse and for how long.  Realistically, I won't be able to plant anything outside until probably early June, but that doesn't mean that all of the plants have to live in a greenhouse until then, especially the herbs.  Once they've adapted to their larger pot, I'm expecting to be able to move them into the house and grow them like house plants near a south-facing window. 

The two issues that most affect this decision in terms of the tomatoes, though, is their sensitivity to cold and their expected height.  When I was picking out seeds, I intentionally ordered ones that do well in colder areas with a shorter growing season.  In particular, the Red House Free Standing, Santiam, Oregon Spring Bush, and Crimson Sprinter all are supposed to more or less mature early and tolerate cooler conditions.  These are tomatoes that I feel like ultimately could be transplanted to containers and placed by south-facing windows, and that with possibly the addition of some supplementary light (probably the red "bloom" light), they'd do fine.  The Crimson Sprinter tomato apparently doesn't even need full sun.  The cherry tomatoes (Maglia Rosa, Fox, and Chadwick) and specifically the Pimientos de Padrón, I think are going to need the warmer temperatures and the regular intense lighting of a greenhouse.  The Pimientos de Padrón in particular supposedly require at least six hours of full sun daily, and I really don't think that they would consistently get that even by a south-facing window. 

In terms of height constraints, though, it's useful to know if the tomatoes are determinate or indeterminate.  The determinate tomatoes are the bush tomato plants that typically reach a specific height and stop growing, and also mature all their fruit at once.  These are supposed to be better for container gardening.  In contrast, the indeterminate tomatoes are the vines that never stop growing and continue producing and maturing fruit until they're killed by frost.  Of the tomato plants that I'm growing, four are indeterminate (the cherry tomatoes and the Oregon Spring Bush), two are determinate (the Red House Free Standing and the Santiam), and the Crimson Sprinter is semi-determinate, meaning that it probably won't get too tall, but may produce and ripen fruit over a longer period or produce two crops over a season.  Here's a nice list characterizing some commonly grown tomato plants.

The Seeds of Change description of the seeds I purchased predicts that the determinate Red House Free Standing and the Santiam tomato plants will both reach a maximum height of around 30", which is pretty short compared to the 6' vines predicted for the indeterminate Chadwick and Fox cherry tomato plants.  I think this is another reason to try to keep them in a greenhouse where I can ensure that the longer vines are still being illuminated uniformly.  Ultimately, I should be able to transplant them in the garden once it's warm enough and they should continue producing fruit until frost.

Dukat Dill sprouted, insulation issues

I seem to be having the same situation with the Dukat Dill as with the tarragon: very sporadic germination.  There´s at least one solid sprout, and a couple of others that have broken the surface, but don´t seem to be doing much.

Dukat Dill, day 16:

Overall, it's not a very impressive germination yield at day 16 considering they were supposed to germinate in 10-14 days.  It's possible that the tray is too warm for them.  The seed packet says a soil temperature of 60-75F is required, and it's possible that since tray 2 is closer to the heater and has the seedling heat mat that it's significantly warmer than 75F.  Maybe I should try re-sowing them in the tray 1 slots where the tarragon didn't germinate. 

The flannel sheet greenhouse insulation seems to be working well now.  I quickly found out that there were consequences to increased insulation, mainly, the heater didn't turn on as frequently.  Ultimately, this was what I wanted, but not at the expense of the plants on the top shelf (farthest from the heater).  Two mornings in a row, the temperature of the top shelf was below 70F. 

My current solution to this problem is to wrap the heater shelf less than the other two.  I also re-taped the edges of the greenhouse structure where the plastic sheets overlap so as to prevent heat and moisture from escaping.  It seems to be working; the temperature of the top shelf was above 70F this morning, which is where I'd like to keep it.

greenhouse insulation and sage and marjoram slideshows

We've had several nights in a row now with temperatures down almost near 0F.  Since the only source of heat for the sunporch comes from the room attached to it, the temperature outside the greenhouse is dropping below 40F at night.  This means that there's a temperature differential of around 30 degrees between tray 1 on the top shelf and the air just beyond the thin plastic sheet.  Not that I don't trust the little electric heater that's keeping the seedlings from freezing, but I've decided to give it some help.  I'm now wrapping the greenhouse structure in two layers of flannel sheets.  This has two benefits. One, it should help to better insulate the greenhouse, saving me some money on my electric bill.  And two, the white inner lining of the sheets should serve as a better reflector than the translucent plastic sheet, meaning more of the light stays bouncing around inside the greenhouse.  During the day, I raise the sheets on the side facing the window in case it actually stops snowing at some point and we get some direct sun.

Front view:

The bright patch in the middle of the front is not some fancy design or lighting scheme, but rather a hole ripped in the inner sheet.  It does demonstrate, however, how much light the sheets are actually blocking and reflecting back into the greenhouse.

Side view:

It doesn't look like much, but I think it's helping.

As I mentioned in a previous post, the garden sage and syriaca zaatar marjoram have both sprouted and seem to be doing well.  Here are slideshows of their progress so far.

Syriaca Zaatar Marjoram (click for bigger slideshow in Picasa):



And the Garden Sage:


Their primary leaves already look like sage!  These little seedlings just amaze me.

germination and primary leaves slideshow

I've been reading up on germination to learn the correct terminology for all the stages of development I've been seeing in the greenhouse. A seed consists of four main parts: the seedcoat, the endosperm, the cotyledon(s), and the embryo. When a seed is exposed to heat and moisture, it begins to germinate. The first bit of green to break the surface is usually the hypocotyl, and the pronounced bend that is typically seen is called the hypocotyl arch. With sufficient light, the hypocotyl will straighten itself, and the cotyledon(s) emerge. All the plants that I'm growing are dicots, meaning that they have two cotyledons. They look like leaves, but their job is to supply food to the developing plant until the primary leaves can take over. Eventually they turn yellow and fall off when they are no longer needed by the plant.

Cilantro germination:


First primary leaves slideshow (click to view larger and prettier in Picasa):



In younger seed news, the Garden Sage and Syriaca Zaatar Marjoram have sprouted in tray 2, and the Dukat Dill is just now starting to emerge, along with a single tarragon sprout. I'm starting to wonder about these tarragon seeds. Maybe it wasn't lack of heat in tray 1 that caused only three seeds to germinate.

new books / light fixture, lots of pictures soon

Almost all of the seedlings have now put out their primary leaves. I'm still trying to catch up on pictures taken by my guest gardeners and photographers over the break, but should be able to upload pictures soon. Meanwhile...

I had quite the greenhouse Christmas ranging from books to gardening supplies to monetary donations for greenhouse upgrades. My gardening book collection now includes the American Horticultural Society's Northeast SmartGarden Regional Guide, Greenhouse Gardener's Companion by Shane Smith, and two books by Eliot Coleman: The Winter Harvest Handbook and Four-Season Harvest. I've already started the earlier of Coleman's two books, Four-Season Harvest, and am really enjoying it. I find it to be informative and well-written. It's clear that Coleman and his wife, Barbara Damrosch, are passionate about organic gardening and fresh nutritious vegetables. They make the distinction early in the book that their gardening techniques are not about extending the growing season (as I am doing with heat and light), but rather extending the harvest season through succession planting and crop protection. I think that their information on harvest-season extension and cold-hardy crops should prove beneficial regardless.

While traveling, I finished reading Fresh Food from Small Spaces by R.J. Ruppenthal. This is a good book about container gardening, and has several thorough sections on building a range of indoor gardening supplies such as self-watering containers, trellises, mushroom colonies, chicken coops, etc. He's also quite the sprout advocate, describing not only how fast-growing and nutritious sprouts are, but also providing numerous sprout recipes and juicing options. It was a pretty informative book, but at times had a bit too much "this will be useful in the coming Armageddon" for my taste.

With the help of some monetary donations from my family, I have bought a new light fixture for the greenhouse. It was becoming apparent that the one 2' T5 bulb per shelf set-up was insufficient to light the seedling trays. The plants along the rim of the trays were growing diagonally (called phototropism) to try to reach the light that was primarily illuminating the middle of the tray. To fix this, I bought a 2-bulb 2' Ultragrow T5 fixture from Harvest Moon Hydroponics for $92.95 (price includes two bulbs). I would've purchased the slightly cheaper Sun Blaze 22 system from ACF Greenhouse, but because of the holidays, they weren't shipping any new orders until the week of Jan. 5th, and I didn't want to wait that long. I installed the new fixture on the top shelf and combined the two 2' T5 single fixtures on the second shelf.

Top shelf:
Second shelf:


I had two choices of T5 bulb for the fixture: grow and bloom, with color temperatures of 6500K and 3000K, respectively. I don't have a good conceptual understanding of color temperature yet, but I'm looking into it. I do know, though, that the grow light emits primarily in the blue spectrum, while the bloom light is primarily red spectrum light. I originally installed one grow and one bloom light in the fixture, but after some reading, it's seeming like the top shelf should probably have two blue spectrum grow bulbs, since it receives very little natural light from the window. Also, the Greenhouse Gardener's Companion says that unless I'm trying to trigger a plant to flower (by lighting it for less time), that I should be lighting the greenhouse for 18 hours a day, so I modified the timer settings for the fluorescent lights to 6 AM - 12 AM instead of 7 AM - 10 PM. It seems like this book is just what I've been needing.