Given the way the data fields are worded, I always assumed that the "Minimum Cold Hardiness" zone was the lower range of what could be tolerated, whilst the "Maximum Recommended Zone" was the highest heat that could be tolerated. Under that interpretation, there is no contradiction, but I can see what Baja is getting at.

I think we need additional input here. @Calif_Sue, @Zuzu, @KentPfieffer, @robertduval14, @Dave - thoughts, please?

Australis said:Given the way the data fields are worded, I always assumed that the "Minimum Cold Hardiness" zone was the lower range of what could be tolerated, whilst the "Maximum Recommended Zone" was the highest heat that could be tolerated. Under that interpretation, there is no contradiction, but I can see what Baja is getting at.

That's what I've always thought also.

Zones are defined based on cold, not heat. Our annual high temperature here in mild zone 11b is lower than the annual high temperature in zone 4a Bismarck, North Dakota.

Baja_Costero said:Zones are defined based on cold, not heat.

In that case the wording for the data field needs to be changed to "Maximum Recommended Cold Hardiness Zone", or it seems quite a few people are going to misinterpret it.

Better yet, stick a big bright warning on there saying this is to indicate which plants require winter cool/cold for viability and/or productivity. The way it's labeled right now is perfectly clear unless you imagine some connection with heat (that clearly does not exist in the definition of the USDA zone system).

I don't know if this has anything to do with it, but I have been searching for all plants in the database (and adding them to my list) that are (minimum) zone 4b, but never put a maximum zone recommendation into the search, that way my searches won't be limited, for I just need anything from zones 4b and up. I think that maybe when you select a maximum recommended zone, a choice bar should pop up asking them to select either what Baja said about the winter or some other seasonal option.

Just my thoughts.

If I need to reword this, then please say so because I know I may have made it sort of confusing, for I didn't add examples or anything.

I don't pay much attention to zones (temperate area) but anything that clarifies the database is a good idea to me.

Baja_Costero said:The way it's labeled right now is perfectly clear unless you imagine some connection with heat (that clearly does not exist in the definition of the USDA zone system).

Not everybody uses the USDA zones or is necessarily fully aware of their definitions. Remember, I'm in Australia, so it's easy to forget that the USDA zones are based on minimum temperatures.

With all due respect, to anyone who can't be bothered to learn the basis for the USDA zone system (which is a mere Google search away), I would ask you to please refrain from filling in the max zone for any plant in the database. We can certainly label the form better, and maybe there might be some useful solution that way. I would think seeing info like this

Zone 9a -6.7 °C (20 °F) to -3.9 °C (25 °F)

in the fields for Max zone would reinforce the key detail. These definitions are shown in the fields for the zone minimum, but for some reason they do not appear under Max zone on the form where we specify this information.

In case my attitude seems overly blunt or critical, I'd like to extend a kind invitation to anyone who is at all unsure about how the USDA zone system is defined to please ask me by Tree-Mail and I will be happy to explain at whatever length may be necessary to resolve the confusion.

Before I fill in any max recommended zones in the PD, I'll look it up Baja

Don't even enter a maximum zone unless you know that a plant requires a certain amount of winter chill or frost to perform well. The maximum recommended zone is useful in the case of herbaceous peonies, for example, or roses of the Gallica class and some others that will not bloom reliably in zones above 8.

Part of the problem is the plethora of entries listing USDA Zone 11 as the maximum. This problem dates way back to the beginnings of our database, when the maximum zone choices only went up to Zone 11. Now they go up to Zone 13, and that option is chosen when people merely mean to say that a plant does well in, for example, USDA Zone 5 "and warmer."

Baja_Costero said:We can certainly label the form better, and maybe there might be some useful solution that way. I would think seeing info like this

Zone 9a -6.7 °C (20 °F) to -3.9 °C (25 °F)

in the fields for Max zone would reinforce the key detail. These definitions are shown in the fields for the zone minimum, but for some reason they do not appear under Max zone on the form where we specify this information.

As I've said, this is where that field would benefit from clearer labelling. It would remove any ambiguity for users and it should be a really simple fix to avoid needing to keep explaining.

This is not the first time the subject has come up, and I don't remember any of the changes I suggested last time being implemented on the database form. So if I were you I would concentrate on educating yourself and the people around you, and not filling in the max zone field or approving such requests for the database without a lot of careful scrutiny.

Only recently been contributing, though not a new member (life and other responsibilites got in the way) but I have been quilty of some of the mistakes being discussed (feet and inches). My apologies to the admins, I won't make that mistake again.

Fascinated with the maximum temp discussion - I'm a zone 3 gardener where minimum cold temps are helpful, but I have to say: I have one plant listed by everyone as a zone 3 that refuses to survive here, while there are many zone 4 plants that thrive in my gardens - and crocosmia 'Lucifer', a solid zone 5, has flowered here for many years and survives the winters well. From that point of view, I think zone recommendations are precisely that: guidelines, not hard and fast rules.

The question of listing or not listing maximun temps, while interesting and irrelevant to many, matters to me: plants that require a cold period or outright dormancy do much better in my zone 3 gardens, where dormancy is not a choice but a way of life.

And in response to the naive soul in a warmer climate who stated 50 degrees or colder does not happen...? My basement frequently drops below 50 degrees Farenheit for much of the average (5 to 6-month) winter here. There are things I cannot leave in the basement over the winter, on the chance that... when we hit -40, they may get too cold. And no: why would I waste money heating an area of the house that I don't use (other than storage) much of the time?

The basement is the least expensive part of a house to maintain in a cold climate, adds quite a bit of space for storage: apples, preserves, root veggies and many other items (including garden bulbs that want to winter over in a cool place but stay above freezing). I have geraniums down there right now that I will repot next spring - and yes, it's been snowing here for the past two days.

When I list a maximum zone for plants, I truly do believe they will not reliably grow / survive above those zones, they genuinely do need a period of year to be cold.

Wanted to add this reminder when adding photos and selecting the appropriate gallery:

For the database, habitat means the environment in which a plant is growing in its normal, natural and wild environment, as opposed to an artificial or planted and cultivated environment such as a garden or greenhouse.

And another on selection a gallery when submitting photos, comments taken from both Dave and Zuzu:

Photos of an experiment or a demonstration of different growing conditions or things like that is not documentation. Data derived from such an experiment might be. But we intend documentation to refer to historical documents and official records.
So the documentation gallery is for some type of documentation, an illustration, a page from a catalog, a tag or signpost, etc.