Hydroponics: An Update, by D.P.

Today I have an update for you on my hydroponics adventures. The system has been up and running all season (April 20 – November 1) so there is a lot of information to be shared. The system currently includes 12 beds – 4 outdoors and 8 in a greenhouse – for a total surface area of 56 sq.ft (~ 5.5 m2). An in-depth description of the system was published last year on Survivalblog. I made only 1 substantial change since then and that is in the way the polyethylene drain pipes are connected to the beds. The connections need to be made with threaded nipples/tees otherwise the system will continually leak. You will need to put a threaded ring on the nipple before you screw it through the bottom of the bed into the tee. This allows proper stabilization of the connection. I made the ring by cutting a slice 1-1.5 threads deep off the tee which has more threads than you need anyway. If you collect the drain water in a gutter underneath the beds, you won’t have this problem but then you have to clean the gutters at least once a month of algae growth.

Before I get to yield discussion and crop notes, there are a few points that I want to bring to your attention. Last year I mentioned some of my reasons for putting in a aquaponics system but I feel I should spend some more time on that. I know gardeners take pride in their craft and are trying to do the best they can under the circumstances; regardless if you are shooting for the biggest pumpkin, highest yield or favor an organic approach. I, too, have spend most of my life taking care of dirt gardens and trying something totally new and unknown can be a daunting exercise. Nevertheless as circumstances change we do well to re-evaluate our methods from time to time. Like most I have been told that survival is for fittest. This idea seems to go back to Mr. Darwin’s trip to the Galapagos islands where he found lots of songbirds each of which was well adapted to a particular niche in the ecosystem. I should point out that I have reservations whether this observation justifies the ‘survival of the fittest’ ideas. It does if you define fittest as the best adapted individuals. If you define fittest as ‘biggest bad*ss’, I suggest Mr. Darwin’s observations lean toward the opposite. At any rate, I decided to follow nature’s lead and look for an approach to gardening that is more adaptable than a run-of-the-mill dirt garden. Hydroponics seemed to be the most promising approach because it can be adapted to almost any situation. In no particular order:

– A hydroponic or aquaponic garden has a much smaller footprint due to higher yields, longer growing season. – Easy to cover against frost or precipitation due to small footprint.

– Less work throughout the season. Once everything is growing you check the water level (add some if needed) and the fertilizer level (add some if needed). During hot weather I had to add water every day. Early summer and fall as little as once a week. Since my holding tank (which I also use to create manure tea) is located above the collection tank, most of the time that meant opening a valve and closing it again once the collection tank was full enough. – Relocating: I need about a day to dismantle the system and another two to put it back together when working alone.

– Legal problems: The desire of bureaucrats and big business is to control your life, including what you eat. As far as I know there are no laws specifically against gardening yet (use of heirloom seeds is debatable since a 1% contamination with GMO seeds could land you in legal trouble but if it gets to that point a small system is much easier to conceal.

– No decent/good land available: that’s okay, I don’t need any. Plants seem to thrive in just about any medium as long as its kept moist and aerated.

– Lower fertilizer usage due to no leaching by ground water / adsorption to soil.

– Decreased use of chemicals: quick growing healthy plants are better able to fend off attackers and soil borne diseases are eliminated. Plants also can’t pick up chemical residue from the soil. Here you can read up on glyphosate and why you want to grow as much of your own food as you possibly can.

– Droughts/water shortages aren’t a problem as the system gets by on 10-15% water usage compared to conventional crop raising methods.

– Climate warming: not an issue; might use a bit more water but plants can be easily shaded. – Climate cooling: more of an issue for me due to my location. Our growing season for a dirt garden is roughly May 20 – September 1. A drop in temperatures of 2C would probably shorten my season by several weeks and cause slower growth throughout the remainder, resulting in a number crops barely reaching maturity and definitely have lower yields. I do not have a lot of leeway as I already have to use short season varieties. Solar cycle activity and increased volcanic activity both say we are heading in this direction; recent presidential executive order notwithstanding.

– Power usage: I know there are people who believe that hydroponics takes a lot of energy but this is only true if you waste your energy in a poorly designed and/or run system. What you DO need is a reliable power supply i.e. photovoltaics. My system ran the entire season on a 60W panel and during May, June, July and early August the controller routinely disconnected the panel in the afternoon to prevent the batteries from overcharging. During October when we had cloudy weather for days on end battery voltage dropped to around 12.3V resting voltage but this is no cause for concern.

I will have more notes on the system itself later on but lets take a look at the crop results first:

Red beets – 5 lbs
Onions – 8 lbs
Turnips – 7 lbs
Potatoes – 5 lbs (mostly small tubers – lower ones showing wet rot)
Green beans – 4 lbs
Pole beans – 6 lbs (3 plants – slicing variety)
Tomatoes – 10 lbs (cherry type – 3 plants)
Tomatoes – 15 lbs (standard size – 3 plants)
Cucumbers – 48 (English cucumbers 8-10″ long – 5 plants)
Soybeans – 13 oz (~ 370 gr)
Cauliflowers – 3
Cabbages – 6
Kale – 8 freezer bags
Peas – 8-10 pods/plant (mostly small peas)
Radish – 2 crops
Lettuce – May 25 – July 20 4/5 cuttings per week – October 1 cutting

All in all not too bad for 56 sq.ft but keep in mind that this year was reserved for testing. Just to find out what’s possible and what doesn’t work. That means I planted some crops in places where I expected them to fail – and I was right: some crops didn’t thrive at all, bringing down the averages. For instance:

The red beets and lettuce were seeded besides tomato plants; as the tomato plants spread the beets and lettuce stopped growing once the canopy above them became too dense to let any light through. – onions and potatoes effectively got finished off by a mid-summer heat wave. They didn’t die but stopped growing and never really looked healthy and fresh after that. For the potatoes I more or less expected this result but I had to put them inside the green house to be able to plant them early. –

Peas had similar issues with the heat though they were mostly mature by then.

Turnips spent most of their energy growing nothing but leaves until temperatures cooled down in September

The green beans were too close to the water and nearly succumbed to a fungal outbreak – growing cabbages indoors is a complete waste of space

Most of the other crops did really well (or better): direct comparisons of lettuce (before the tomatoes got too big), cauliflower, cabbages (outdoors) and soybeans suggest yields of 5x to 6x that of same variety plants in the adjacent garden. That doesn’t mean that the cabbages/cauliflowers were 5x as big but they grew to normal size heads on 4x area density (1 plant/sq.ft vs 1 plant/4 sq.ft) and took a month less time to develop. Soybeans were seeded on the same day in the garden and in the system. The soybeans matured about a month later and yielded some 5.5x as much per sq.ft as the garden soybeans. For those of you familiar with soybean yields: due to our short season and low soil temperatures soybeans will mature but with rather low yields; this year’s garden plot yielded the equivalent of 25 bu/acre even though they did get fertilized (but at lower rates then commercial recommendations). The hydroponics bed was seeded with roughly twice the beans per sq.ft and yielded on average larger size beans and more pods per plant. Also of note is the yield of the pole beans; a crop that I cannot grow in the garden because they usually start to bloom around the time of the first frost which leaves me with little to show for my efforts. Cucumbers do a bit better out in the open but yields are quite unpredictable because the weather needs to cooperate around the time the plants are maturing. Most years putting 5 plants in the garden will yield 10-12 cucumbers. If I want to count on more I need to start more plants. This year we had fresh cucumbers for about 6 weeks straight.

So why these big differences? I think there are a number of reasons: – water is more available to the plants and plentiful (not as much heat stress) – nutrients levels in the water are much higher – related to those: root systems are much smaller requiring fewer resources to build – average water temperature was higher than area soil temperatures

Following is a condensed version of the notes I took throughout the season. Seedlings. I had some real problems getting seeds of some crops started this spring. I now believe this was due to the seeds overheating. The top layer of the gravel beds gets much warmer than the top layer of soil when the sun hits it. Consequently the worst results came from crops seeded on sunny days. Seeds germinating in cloudy weather and in shaded areas did much better. I didn’t actually bother to work smaller seeds into the ‘ground’. They seem to settle into the spaces between the gravel particles well enough that they absorb whatever moisture is needed to get started.

Red Beets. Respectable crop even though even though they were put in the wrong place at the wrong time. Very sensitive to UV damage if grown under PVC panels. I will give them a better chance to strut their stuff next year.

Onions. Grow on coarse bed and limit flooding to avoid constantly wet bulbs. This leads to mold on outer skins. Should be planted in outdoor bed preferably facing north.

Radish. Very easy to grow all season. Can be seeded together with other crops between the rows since they are ready for harvest in 20-25 days.

Spinach. Plants bolted into seed before growing their 6th leaf. I may try seeding them in late August as a fall crop next year.

Cabbage/Cauliflower/Broccoli. Indoor beds: lots of leaves on long stalks but tiny or no heads. Outdoor beds: plants develop quickly with normal growth pattern.

Leek. Grows very fast – just not upright because stems can’t support the weight of the leaves.

Rutabaga/Turnip. Lots of leaves all summer but no product. Roots started developing in late August as weather turned cooler. Will try again in outdoor beds next year.

Potatoes. Not a lot of potatoes produced mostly due to heat stress. However what I really wanted to know is if potatoes will grow vertically in layers or just at the base of the plant. On the internet I have seen a number of videos from people trying to grow them in enclosures with a small footprint but plenty of depth. Alas most show people building enclosures and planting crops but no harvest videos. I did come across a comment that pointed out this method only works with long season varieties of potatoes. In effect: use European varieties, not North American varieties. I managed to source a variety called ‘Bintje’ for my trial and indeed a number of tubers were growing directly out of the stems about 8 to 10 inches above the base of the plant. So it seems possible, though I don’t see the enclosures as a useful solution in my current location because the growing season is simply too short. I put the left-over seed potatoes in my garden and got about 4 weeks worth of potatoes out of them. Bintjes are yellow fleshed and make very good tablestock potatoes.

Tomatoes. Very heavy feeders. Use lots of water when mature. I figure the 6 tomato plants consumed about half of all the water that I put into the system for the entire crop season. They also don’t seem to compete well with other plants when small; once their root systems develop that disadvantage disappears. Canopies don’t let any sunlight filter through.

Cucumbers. Grows along chicken wire and fence wires. Very open canopy: plants growing underneath didn’t show any problems. Quick to show Mg deficiency.

Lettuce (leaf type). Very easy to grow: just put in seeds and wait for plants to grow. I did get 4-5 cuts from each plant whereas I am lucky to get 2 cuts from plants growing in the garden.

Peas. Did okay, but not better than plants in the garden. Like cucumbers its a good crop to plant along the edge of the beds because peas climb straight up along a wall and therefore take up very little space in the beds.

Pole beans. Use climbing supports. Quick to show Mg deficiency. Heat wave was rough on plants but they adapted in a few days and showed no lasting effects. I had the plants grow straight up about 20″ and then spread out horizontally along a panel made of chicken wire. The three plants completely covered an area of 5 ft by 2 ft with an open canopy: didn’t seem to adversely effect plants growing underneath it.

Short stemmed green beans. Yield was about the same we get in the garden. Grown in both indoor and outdoor beds with similar results though the indoor plants were more susceptible to disease: a white fungus causing both stems and beans to rot. Pole beans are much better for this environment.

Soy beans. Grown outdoors. Did very well. No diseases and excellent yield.

Hydroponics Setup

The heat exchanger panel is made from an old storm window and a piece of steel siding that I cut to the size of the window frame. The front of the steel was painted matte black and against its back I fastened a piece of 1″ thick styrofoam. In between the window glass and the steel plates I put three pieces of black painted 1/2″ copper pipe in parallel and running the length of the window. Tees and elbows connect these pipes to headers and water is pumped through them. This setup works surprisingly well and has no problems raising the system’s water temperature into the 70s for most of the season. Water is pumped directly from the collection tank into the panel and the return line goes back into the collection tank. I am using a low volume (8 lpm / 125 gph) pump with the panel so pressure and energy use will stay low. Still this pump consumes more energy than the flood pump because it runs continually. For this reason the pump is only allowed to run if battery voltage is 12.6V or higher. The panel is also outfitted with a temperature sensor between the steel siding and the window. Its highest reading this summer was 90C (~195F). – The water temperature in the system closely tracked our soil temperatures. Though the heat exchanger would raise water temperature during the day, by the next morning it would drop again to around 60F in mid summer and lower in spring and fall. This could be due to the fact that the collection tank resides underground with just its top showing above ground. To curb heat losses I have dug up the tank this fall after the system was shut down and have insulated it with 1″ thick styrofoam strips that were glued to the tank with polyurethane insulation foam. So next year I will find out if underground heat loss was really the culprit or that most losses come from low overnight air temperatures. – One thing about putting the tank underground (and painting its top black) is that it completely eliminates algae growth in the tank.

If possible put photovoltaic panel and heat exchanger panel on south side [in the Northern Hemisphere.] It is important that they can be turned to the sun early in the morning because in spring/fall there is less cloud cover at that time of the day. – Ideal slope of growth beds is slightly away from drainage hole to keep some extra water in the bed. – When using a 55 US gallon collection tank, the system should include no more than 16 beds to avoid running the pumps dry in hot weather when the most water is used. Max water use is around 10 seconds pump time per bed.

– The greenhouse is made of PVC sheets which seem to block all UV light, leaving the plants without any protection if the sun’s rays happen to hit them. Exposure to the sun for about half an hour was enough to discolor leaves from green to yellowish green and stunt growth for approx. 4 weeks. The same thing happened to plants that I started indoors once they got transplanted outdoors. I have never seen this happen when starting plants behind glass. Some crops seem to be more susceptible than others and the problem can be avoided by exposing plants to direct sunlight for 15-30 minutes per day from the time they are seedlings. – Water pumps should be reliable. My main flood pump is a 12V bilge pump (1000 GPH) that has worked without a single glitch for 2 seasons now but I do have a backup pump on hand. Finding a low volume circulation pump for the heat exchanger has been more problematic as the cheaper pumps generally lasted only 6 weeks before gumming up / seizing up / burning up. I have settled on a soft start pump which has been up to the task for the second half of the season. As an added bonus the pump has built-in overload and dry-run protection.

– Underwater electrical connections need special attention because the growing solution is salty and slightly acidic and therefore very corrosive on solder joints. I found two approaches that work for more than a few weeks. A) pack the connection in a gasket forming material, slide heat shrink tubing over the connection and shrink it to create a very tight gasket around the wires. B) take a few inches of 1/4″ copper tubing and squeeze it shut on one end. Put a few drops of molten wax or paraffin in the tube. Put your connection into the tube and fill it to overflowing with more molten wax. Let the wax solidify and put a piece of heat shrink tubing over the open end of the tube to protect the wax from mechanical damage. This approach works really well for sealing sensors.

Watering the plants. There are two important variables in an ebb and flow system. The quantity of water pumped into the beds each cycle and the time between floodings. The term ‘flooding’ should not be read as having water run over the growth medium. Plant roots are designed for moist environments – plant leaves and stems not so much. I set the valves and pump times so that you could just see the water rise between the pebbles at the time the pump shut off and this works very well. To automate the task one of the beds is outfitted with a float sensor which opens when the desired water level is reached.

Early season cycling (=time between floods) can be as long as three hours because seedlings do not seem to care for being flooded often and there will be plenty of moisture for them in the beds. Decrease cycle length to 70-90 minutes when plants start to grow. For mature plants use 30-45 minute base cycle. During cool weather (<60F) the base cycle is automatically doubled. In warm weather (heat exchanger temp. >90F) the cycle time was reduced to 20 minutes. In hot weather (heat exchanger temp. >110F) the amount of water pumped into the beds was increased by 25-30% to make sure the beds won’t be sucked dry before the next cycle starts. If too much water gets pumped into the beds, the float sensor automatically shortens the next pump time to avoid overflows. At the onset of hot weather it is important to cover the roof with tarp to avoid overheating of plants because they are not yet used to high temperatures. It seems to take only 2-3 days for them to adjust though. Also provide for plenty of air circulation. Warm weather night time cycle was set to 1 hour otherwise beds can be sucked dry through evaporation causing plant wilting. Cool weather (<50F) night time cycles can be as long as 3 hours without measurable adverse effects.

As you may understand from the above, my goal is to pump as little water as possible without adversely impacting the crops. This is the key to low energy usage. Photovoltaics is an ideal fit to power the system because you need to pump lots of water on a hot summer day when the panel produces the most energy anyway. But on cold and dreary days the plants don’t seem to be too interested in getting wet every 20 minutes.

It would be quite a chore to make so many adjustments but fortunately we have micro-controllers to do the dirty work. My current controller has a light sensor and a temperature sensor in the heat exchanger. From their readings it can figure out day/night and the type of weather. It adjusts the cycle times accordingly. To complete the picture: the controller uses the float sensor in the growth bed to check the main pump’s operation and a water temperature sensor in the collection tank to run the heat exchanger pump. The photo-voltaic panel and battery are also actively managed (through a voltage sensor) to safeguard the crop as much as possible. And if any of the system’s operating parameters goes out of bounds, the controller sounds the alarm which is rather re-assuring. Now, don’t get me wrong: I understand the risks in going hi-tech. But the system can still run fine off a basic timer for the flood pump; its performance just won’t be as optimized.

For most of the season I used rain water collected from the roof of the greenhouse as feedstock for the system. The water was collected into an old trashcan, tested and pumped into holding tanks if approved. Rain water quality was good most of the year. Total Dissolved Solids (TDS) levels approached those of de-ionized water (<10 ppm) and only once (end of June) did a cold front deliver elevated radiation levels. At twice background radiation it wasn’t anything to worry about but I had plenty of water on hand so this got dumped.

Fertilizing. Plants need minerals to grow and the bulk of phosphorus and potassium came from 10-10-10 commercial fertilizer. Additional quantities would have come from the manure tea I used but how much is hard to quantify. 10-10-10 fertilizer was added by dissolving 3 handfuls in a pail of water and adding the solution to the collection tank. This was done once or twice a week as needed. Total quantity used for the season was about 10 lbs. As the plants got larger extra nitrogen was added in the form of 30-0-2 (golf green) – total quantity for the season about 3-4 lbs.

Since the system was started with plain tap water, I raised the fertilizer levels in the course of a few weeks to make sure the young plants’ roots wouldn’t get burned. Although a gradual rise is necessary when plants are used to low fertilizer concentration, it is quite a different story for seeds. In early August I put lettuce, radish and kale seeds in the beds while the system’s TDS level was around 5000 ppm. Within 24 hours all of the seeds started pushing out their roots into the gravel and never looked back. Germination percentages were excellent.

This is all the more remarkable for lettuce which (according to commercial literature) has an upper limit of 800 ppm for fertilizer solutions. However in commercial operations lettuce is usually grown in beds floating on the fertilizer solution and its roots would be in constant contact with the water. I have to assume that ebb and flow systems work very differently from a plant’s perspective because I have seen spikes up to 6500 ppm and the lettuce was growing very fast instead of dying off.

I was shooting for a fertilizer solution strength of around 4000-5000 ppm for most of the season. This worked well enough until the middle of July when I started to see strange readings to the point that I thought my TDS meter was broken. After a few days of more frequent testing I started to see the pattern: very high readings at sunrise that kept dropping throughout the day. For example 6470 ppm at sunrise -> 5250 ppm around 9 AM -> 4450 ppm at 7PM. Then it dawned on me that I had 2 beds of beans in the system, hosting lots of bacteria that were very busy fixing nitrogen and releasing nitrates into the water. To give you an idea of how much nitrate was added by the bacteria: if I dissolved 3 handfuls of golf green fertilizer (almost pure ammonium nitrate) in a pail and added them to the system, it would raise ppm readings by around 675-700 ppm. The large nitrate releases happened until the end of August, after which they started to get smaller (around 200 ppm swings by early October). The main thing is that the bacteria like warm water (70-75F); if the water temperature stays below that they work a lot slower.

Needless to say that some of the crops really took off at that time with tomatoes and cucumbers the biggest beneficiaries. This also resolved one of my biggest concerns: in case commercial fertilizer becomes unavailable, using manure tea will work fine for phosphorus, potassium and most other required elements but dry manure is very deficient in nitrogen; the very element that regulates plant growth. You could use fresh liquid manure which still retains a large portion of its nitrogen but that is rather messy. Instead I will just plant more beans!

Tomatoes and cucumbers showed signs of magnesium deficiency early on so this element was added to the solution from time to time and no more problems were encountered. A good source of magnesium (and sulphur) is Epsom salts (MgSO4.) Kelp extract and ocean salt were added to provide some additional trace elements, however I have no way of knowing if the system would have been deficient without the additions.

If you are interested in how well balanced your plants diet is, you should get a piece of software called Hydrobuddy. Its free to download and comes with its own database of plant nutrient requirements for many crops and chemical analysis of a lot of commercially available fertilizers. You can also add your own concoctions to the database provided you have some idea of their chemical analysis. You can tell the program how much fertilizer, manure, blood meal, etc. you use on which crop and it will tell you how well balanced your crop’s diet is on all important nutrients and trace elements.

And don’t forget to get your own TDS meter while you are at it. They sell for about $8 and are worth every penny if you want to get a feel for what is going on. Another thing I should mention in case you haven’t already done so: it is still very easy to find good pictures of nutrient deficiencies and diseases in crops on the internet. You probably should download some for future reference.

Corn trial. I also tried growing several varieties of flour corn in the garden this year. Only the short season varieties properly matured – no surprise there. But I will highlight 2 varieties that stood out. Bloody butcher was the only variety that withstood high wind gusts without needing additional support (i.e. getting blown over). However its borderline feasible at this location as it barely reached maturity and that only thanks to warm fall weather. Mandan Red Clay stood out in two ways: the plants looked miserable all summer, barely growing to 3 ft high with lots of tillering. Nevertheless they managed to grow 6″-8″ cobs with 8 rows of large kernels that fully matured. That produces a well above average yield-to-total-biomass ratio which may come in handy some day. Red Clay does not like cramped quarters; in narrowly spaced rows a high percentage of plants did not grow any cobs.

Next year’s plans. With blind testing out of the way, next year’s plans are taking shape. First up is to try to get the system up and running around April 1. Inside the greenhouse I will focus on growing leafy vegetables like broadleaf lettuce, swiss chard, endive and purslane. Radish and cucumbers will also be grown inside and I would like to try some pepper plants just to see what happens. Onions, turnips and red beets will move to the outdoor beds.

I also plan to add 4 more outdoor beds that are spaced farther apart then the current beds. This is not a problem: I just need to add a few extra yards of polyethylene pipe between them. The reason for this is that I think I can grow a 10ft x 12ft patch of pole beans over top of a single bed. I could let the beans grow vertically but the terrain is rather open and susceptible to wind gusts so I prefer low to the ground solutions. The same is true for my tomatoes and cucumbers, though I know the plants are willing climbers.

Pole beans and cucumbers happily grow along some baler twine, but for tomatoes I prefer something more solid like chicken wire or lattice to cope with the weight of the growing fruits. Its not that your baler twine breaks but it will cut through the stems. Tomatoes may get their own bed or I can take a panel from the side of the greenhouse and simply let them grow ‘through the wall’. One of the nice things about a hydroponics system is that you don’t have to worry about crop rotation so I can select the bed that is most suitably located for a specific crop and build the required infrastructure around the bed without having to change it each year.

I also plan to add strawberries to the mix. The plan is to grow them in 5″ flower ports that are located in a piece of eaves-through where the water flows through. The eaves-through will be suspended about 18″ above the existing beds. Of course I have to get the plants through the winter first: most of them are currently located in a hole in the ground that is covered with clear plastic and snow, so we’ll see how many survive.

And finally I would like to put in a good word for our pollinators. You are probably aware that they, too, are having a tough time surviving. Not just commercial hives but the wild ones as well. For any open pollinated crop that starts out with flowers, you really need them if you want to see any harvest at all. And so there are some things you want to do that are good for both your local pollinators and your crops. – Help out the pollinators by growing nectar producing flowers in the vicinity of your vegetable garden. – Make sure that local pollinators put your garden on their map early. – Avoid use of hazardous chemicals on your veggies as much as possible.

There is quite a bit of information available on what plants attract pollinators but most of those plants are annuals (at least in this neck of the woods) that bloom rather late in the season. Which is no doubt helpful but I want flowers that bloom before my crops. That way pollinators will know where to come looking when I need them. There are plants that bloom early and that seem to provide lots of food. We have two of them around here that are not very common but work out really well. One is a small plant called a grape hyacinth. Its lavender colored flowers look like a bunch of tiny grapes growing upside-down. Time wise it blooms between crocuses and tulips, anywhere from 5 to 14 days depending on temperatures. That is just the time bees and other insects emerge from their winter quarters and they really appreciate some fresh food. These plants require no special care but you have to let the foliage die naturally in summer if you want the bulbs to grow and multiply. Replant the bulbs every third year to avoid overcrowding as they grow few flowers in that situation. The second one is called Angel Wings (Rosa chinensis). These are miniature roses that start flowering late May/early June and for a few days make your garden smell like a rose garden. They continue flowering into fall with ups-and-downs depending on the prevailing weather. Pollinators are strongly attracted to these plants: you can hear the buzz when walking past the garden. Unlike real roses the plants are disease resistant, carefree (except for yearly pruning of dead wood with leather gloves) and very hardy: ours have survived -10F without protective cover on multiple occasions.