The Tropical Fruit Forum

This is the third or so fruit I've gotten from this tree.  Much like the Indio Mandarinquat it is edible but underwhelming.  The rind has little flavor, the interior tastes much like a navel orange but somewhat less sweet and with more pith.  Only a couple seeds.  Hopefully it will improve over time.  I'm going to let the others get a darker orange before I pick them.  This one was pretty soft already, though.

The size of the fruit is quite large for a kumquat hybrid, bigger than a clementine.

These things are great.  Seeded Nagami is obsolete.

Next spring I'm getting married.  Along with that, we are looking at moving to a house with more land (in the same area - Southeast Pennsylvania).  Wife-to-be fully supports my citrus hobby and I am planning on constructing a free-standing greenhouse at the new property.  I am hoping to be able to ventilate well enough to keep my trees inside year-round, planting most directly into the ground.  I'm not sure how realistic this is with 90+F summer high temps here.  I have just begun my preliminary research into this, so I still have a ton of unanswered questions.  I am thinking of something like this http://www.greenhousemegastore.com/product/ventmaster-30-commercial-greenhouse/commercial-greenhouses as the frame/ventilation solution.   I have an initial budget of ~$15-20k.  I don't have a particular size in mind, but I'm thinking at least 25'x50', which is about quadruple my current floorspace, and 15'+ tall, which is twice my current height.  I don't need to move my plants in the first winter as I will still have access to my existing winter greenhouse for the next year at least. 



I know that Millet has a substantial greenhouse in a temperate climate that I can use for inspiration.  I imagine others on this forum have some experience with these things also.  Some of the big questions I have are...

Glazing material:  If I remember correctly, inflated PET sheeting is the best in terms of cost and insulation, but isn't very durable.   Will PET stand up to snow load in temperate states?  I've been extremely happy with the dual-layer 8mm rigid polycarbonate that I use for my winter greenhouse, though I can feel the heat loss through it in winter.  I'm thinking 10mm+ if I go this route.   It isn't cheap, but is far cheaper than something like glass.  I haven't priced glazing a structure this large yet.

Ventilation: My winter greenhouse seems to be fine when buttoned up all the time.  That is, I have zero ventilation beyond whatever leaks out from cracks in the floors, walls, etc.   It doesn't seem to be starved for CO2 as I get lots of new growth each winter.  Is this reasonable to expect for a larger greenhouse or will I need to either ventilate in winter or provide a supplemental CO2 source?  I haven't had an problems with condensation yet.

Heating:  I believe natural gas is the cheapest heat source at the moment.  Would make sense to allow some of the exhaust gasses to flow inside the greenhouse to add C02?  Obviously you would need some kind of sensors to detect dangerous pollutants or CO2/CO levels.  But my understanding is that natgas & propane can be very clean burning if properly maintained.   

Cooling:  my winter greenhouse gets above 115F in the summer when it is empty and the plants are all outside.  Is it possible to keep temperatures reasonable with only natural+fan ventilation?  It would certainly be possible to have a shade cloth either year-round or in the warmer months only.  I'm not sure how much air conditioning would cost but I imagine it would blow my budget entirely and I'd have to rethink the whole project.  It gets humid in summer here so evaporative cooling may not be effective.

Extra insulation: I can feel that the main source of heat loss in my winter greenhouse is the polycarbonate glazed face.  I wonder if it is realistic to have some kind of insulation blanket can roll down at night over the roof of the whole structure - assuming there's no snow?  I could also have grow lights running at this time as supplemental light. 

Water: it looks like most greenhouses can support gutters, which means rain barrels are an easy source of water for plants.  In addition, I would run a water line & spicket out to the greenhouse.  I know that others are using water barrels for heat storage also, I should be able to do the same.

I have a small 1/4 acre orchard of supposedly dwarf & semi-dwarf trees in my side yard.  Some are now 15ft tall and producing more fruit than I can ever eat.  Because of this I don't even attempt to pick anything above my reach as there is plenty of low hanging fruit.  I am thinking of topping everything above ~10ft so I have less to spray.  Is this a bad idea?  I'm familiar with pruning recommendations and I have me trees pruned to their recommended shape (central leader for apples, open for peaches, etc.) and this would be cutting off all the leaders.  Given that the trees are old enough to have a proper support structure... any reason not to do this? 

As of repotting today, my largest tree has reached the limit of my ability to move it in/out of my winter greenhouse, in terms of size and weight.  The root ball had completely filled the ~18" diameter rootmaker pot and is now in one about ~24" diameter.    This is a Home Depot tree so it may not be a dwarfing rootstock.  The original nursery tag is still attached so I may be able to contact them to find out, but regardless it seems to grow and grow.  What's the best way to maintain the current size while still getting fruit?  Cut a third or half way back each year?  Do I need to prune the rootball when using rootmaker pots?

Does anybody know a source of Excalibur Red Lime or specific cultivars of Finger Limes?  I have the green finger lime but I'm told it isn't good quality.  And from what I've seen, the only place to get a Red Lime is a non-exporting state.   I live in Pennsylvania so there isn't anything locally available.

I've noticed that most of my trees seem to have areas of clear, sticky droplets on their leaves.  It only affects maybe 5% of all leaves and seems completely random.  It doesn't seem to match up with where I find mealybugs.  Any idea what this is caused by? This is in a greenhouse.

It looks like water or oil droplets but it feels like dried glue.

Is it reasonable to grow pummelo in a container?  I just tried these for the first time and they are really good.  Better than grapefruit, I think.  Also, I'm not sure if they have higher heat requirements than other citrus.  So far I've had no problems ripening oranges, mandarins, and kumquats.  It would have to weigh less than ~150lbs total, stay under 7ft tall (including container), and survive moving in/out of greenhouse for winter.

I had posted my setup last year on the citrus growers forum.  I've made some minor improvements and so I figured I would give an update.

The original project was to make use of storage space above my garage.  It already needed a new roof so when replacing shingles I replaced an entire face with 8mm dual-wall polycarbonate.

The southern face of 'B' section is what became the greenhouse


This is how it looked before




I added better subfloor as the existing floorboards were barely strong enough to walk on


Work in progress




Glazing complete



Painted the floor white to maximize light


At this point it was already getting late in the season and I had to move the plants in while I worked.


Insulation - fiberglass batts covered with reflective polyisocyanate foam board.  Under the floor I also have fiberglass batts.


Added a door, cut to size and covered with foam insulation.  Doubled up the 2x4s on the walls to add depth for insulation




Added remaining wall insulation.



A nice 1F (-17C) winter day...



...with huge growth flushes



This was a year ago.  Everything has worked out beautifully.  I was able to keep it heated with two 1500w space heaters with built-in thermostats.  I had to use propane on below 0F days but I realized come springtime that what I thought was an on/off switch on the heaters was actually low/hi power and I think I was running at half power all winter!  So hopefully I won't need propane at all this year unless there is a power outage.  I try to keep it at 55F but often it drops into the 40s on cold nights.  Conveniently my local power company just started offering lower off-peak electric rates so it isn't as expensive to heat as I had feared.  From walking around feeling for cold spots on a freezing day it seems like the polycarbonate face is clearly where the heat is being lost.  If I did it again I think I would use 10mm or more.

Condensation has not been an issue at all.  I have yet to see any.  I think the heaters keep it dry.  The biggest problem was watering.  I had set up a slanted bench for watering trees, where runoff water was directed into a pipe that drained outside.  The problem was that the bench could only hold a few trees at a time, and it took hours before they stopped dripping water.  This meant I could only water a few trees a day and I had to rotate them constantly on and off the bench.  I now have twice as many trees so this would be even more impractical. 

My solution this year was to add vinyl flooring and a floor drain.  Because the floor sags very slightly, water tends to flow towards the center.  I dumped a bucket of water on the floor to see where the lowest point was and installed a drain there, with a pipe flowing outside.  I also added an extra support post in the center of the garage to ensure the added weight isn't an issue.  Now I just leave the containers on the floor and let the water spill out and find its way to the drain.

It was getting dark out but here's a picture from today

Are these ready to eat?  Some are still half-green, some bright orange. I remember some varieties are ripe when still green, but I forget which ones.



I'm not sure if I can go by calendar based timing because things got confused in my winter greenhouse.

All of the fruit on my persian/bearss lime have small black dots on the rind.  None of my other trees have this and they're all in the same area.  I assume it is just insect damage but I don't see any insects at the moment.  Any idea what it might be?  Looks very minor but I'm worried it could be fungal or bacterial infection.

Keep in mind I'm in Pennsylvania so most citrus pests aren't around.

Found an immature orange split, still on the tree.  Never saw this before.  I google it and came up with some explanation here: http://homeorchard.ucdavis.edu/8038.pdf

Sounds like environmental factors are the cause including possible draught stress followed by sudden watering, changes in fertilization, and sunburn.  All of these are possible in my case.  We had some dry weather, I watered heavily, the sun hits fruit directly.  Some fruit are slightly discolored which I wasn't sure if was sunburn or normal ripening.  Just thought I'd share. 

This is a moro blood orange:



I ate it, it was pretty good actually. 

My container citrus trees are in very low maintenance mode right now - there is osmocote plus in all containers and they get a mix of rainwater and long sprinkler watering.  Aside from occasionally killing ant infestations I don't really have to touch them.   I remember hearing about June Drop from the other forum as something that was an avoidable problem this time of year.  Is it just a matter of keeping the trees from drying out?  Anything in particular to watch out for?  My oranges have already set fruit, the kumquats are blooming, and the lemons/limes are ... both.