Daylight for plants

[JT101]

Hi everyone

I have had an allotment for several years now, and am starting a forest garden. Still very much a novice in many areas but am learning as I go.

I do get confused by all the different terminology used for the same thing amongst nurseries.

In particular is the light requirements of various plants so I'm wondering if someone can explain for me in layman's terms. I have 2 questions.

1) Most fruit trees say they need say 7hrs sunlight. Now is that 7hrs of direct sunlight non-overcast and clear skies, or is that just 7hrs of daylight of our drab grey skies we often have in the UK?

2) What period is this referring to? Let's say a plant requires 7hrs of direct sunlight. Is that only at the peak on Jun 21st. Or is it throughout the whole growing season?

It's all a bit unclear.

Thanks in advance

[veggiechicken]

Hi JT and welcome.
I do a bit of "forest gardening myself" - as I have several mature oaks and ash trees so have to consider the shade they cast in summer.
IMO "7 hours" of sunlight" means 7 hours of open sky/daylight - in other words, don't plant in dense shadow cast by buildings and immovable objects.
If you plant the tallest plants on the north and stagger the heights towards the south you should be OK.
On an allotment, please have regard to the shadow that your trees may cast on your neighbour's plots. Are there height restrictions for trees at your site?

[nickdub]

My garden is on the edge of a small wood and I've been here for about 35 years.

There are a number of factors to consider of which "sunlight hours" is important, but not the only thing. Rather than trying to detail everything from a theoretical POV, I'd say it would be better if you could tell us more about what you are thinking of doing. If you are considering plum or apple trees the advice is going to be different to that for gooseberries or blackcurrants.

In the end gardening is a practical activity and the site itself, the weather you are likely to get in your area, as well as any trees or whatever nearby all impact on what is possible.

[JT101]

Hi again

I know that there are many factors as you say. I have spent a bit of time modelling the layout of trees and shrubs to ensure all plants get the best amount of light, and least amount of shade. I have two plots, but am struggling to decide about one in particular.

I originally had my fig tree horizontally at the back which runs east-west, and then subsequently discovered that thin profile trained trees on post and wires out in the open (i.e. not against a wall), should be trained north-south. All the rectangular blocks in the images are grapevines, running north-south. The south side............

Since I had so many vines, and I really want my fig to work, I decided to move it to replace one of the north - south facing vines.

But I also have three cordon trees. Originally I had them as upright vertical cordons, but since I want this to be a low maintenance forest garden, I was informed that they would require more work than the oblique ones on a post and wires. So I figured the best place was to replace the fig tree at the back. But of course, you should consider three angled cordons much like a fan or espalier trained tree. i.e. that the north facing side won't recieve any sun and the fruits will ripen less.

Should I also move these three to replace grapevines? I am happy to do this, but want to know that it would improve chances of fruit ripening or is it a miniscule chance?

I also have a cobnut (the blue tree), which could be moved somewhere more shady on the plot. Possibly replacing the apple tree. At the moment I think once the grapevines are in full bloom, the apple tree will get shaded, but the cobnut will get a lot of afternoon sun, which it needs less than the apple tree. The medlar is in the mix too.

Too many decisions. As I said, I know its not an exact science, but just thought I would throw it out there for some opinions.

[JT101]

Images showing which is south

[nickdub]

I'd like to get a few more pieces of information please, before commenting :-

1) roughly what is your location ?
2) is the garden in an urban, sub-urban or rural setting ?
3) what is the approx height above sea-level
4) are there any tall building or trees beyond the boundaries of the garden which shade it part of the day ?

[veggiechicken]

Your plans are not what I envisaged when you said "forest garden" unless you intend under planting with other crops and mixing it up a bit. Nature doesn't plant in straight lines!

https://spiralseed.co.uk/making-forest-garden/

[JT101]

Hi nickdub

So the site is an allotment plot in in the middle of suburban south east london. It is fairly secluded like most allotment sites from the hustle and bustle. Pretty exposed, the allotment runs down a slope of about 3 degrees (which is what my part is on) from east sloping down to the west, and then levels out. The sloping part is heavy clay, whilst the flat is less clay but apparently gets too wet. Anyway, I'm on the slope. I used to get a couple of really boggy spots.

I have another half plot which in answer to veggie chicken is more forest garden like with nearly all bush trees. So on that point, thanks for the reminder. I get a bit lost on the concept sometimes, and I can see from the outside it totally looks like a regular garden. It's going to be a cross between a vineyard (all the long rectangles are grapes on wires and posts) and forest garden. So I am applying the principles of tall things at the back, short at the front, different plant types such as american groundnut etc etc (all the plants from Martin Crawfords book), ground cover like wild strawberry etc. And of course nitrogen fixers like elaeagnus. Yes, lots of understorey plants i.e. herbs and small shrubs! It's just that it's taken me so long to do the design so far that I haven't had a chance to put those in the model.
And yes, I have spent too much time in the virtual world, but I keep visiting the plot to see how it would work in reality.

The principle in this design is to have a mini vineyard, crops I love like figs, cobnut, pears etc, and then mix in more forest style plants and nitrogen fixers as understorey, carefully placing them relative to their shade tolerance.

The elevation is 41.8 m or 137.0 feet from sea level. GPS co-ordinates: 51.39319,-0.04677 if you're interested.

I can post the sketchup model infact. Maybe later I will post an image of my other mini plot, but don't want to confuse the issue right now.

As far as tall buildings, trees etc, the only one that shades my plot is that big orange tree which is 4.5m tall and wide, and is the big orange thing at the front of the image on the south side. It casts a shade of about 4m at it's worst i.e. early october at the extremes of the season here. Not much I can do about that. It will mostly affect the last two rows of grapevines.

So as I said, it's really deciding what to do with that back section, whether to put my cordons there, or steal another row of vines, and go for much shorter plants there. Have to be mindful of my neighbours plot behind. The cordons would come to about 1.5m tall which is just about ok, but can't be putting in 3m shrubs or trees. The vines don't seem to quite shade out the very back of the plot in Sept/Oct or Mar/Apr. Just the feet of anything planted there.

They're not draconian at the allotment about height. 8ft is the supposed maximum, but nearly all the trees at the site are about 14ft or so. Still, I don't want to cast too much shade on my neighbour to the north. I have plots to the north, east and south, but nothing to the west. So anything up to say 1.5m sounds about right. Especially since my greenhouse casts so much shade.

Am I talking myself into moving these cordons? Ii think I might be. Anyway, nothing is planted yet except the vines. I have all the trees, stakes, wires etc sitting in my back garden planted temporarily waiting to go into my plot.

Sorry,bit of a rant

Cheers guys

[nickdub]

Well in general I don't see any reason why you wouldn't be able to make your plan work, given the site you have and its location.

On the whole I'd advise leaving the existing trees which I think includes the fig, apples, the cobnut and medlar where they are for now, just doing normal pruning and cultivation round them you can reconsider whether moving them is sensible after they finish growing this year. My reason being that you have a load of other work planned and I'm assuming you won't be able to spend all your time on the allotment , and that it is more sensible to move trees in the dormant season

I know next to nothing about growing vines in the open but all the vineyards I've seen have just had rows of them running down slopes not inter-planted with anything - whether this is best or just the most commercial method I have no idea. I do think the "big orange tree " on the S side of your plan will give too much shade to the area its next to, to allow growing vines successfully in that small part - may be some soft fruit like currants or gooseberries there in stead ?

Good luck with your project. My best suggestion would be to get as much info on the growing of outdoor vines as you can, obviously the choice of variety is going to be a critical decision - may be start a new thread on this topic ? - In an ideal world you'd be able to get a few days working as a volunteer at a vineyard somewhere, in order to pick stuff up from the professionals.