Plants severely stunted - Looking for the reason

[Phillybonker]

Bit of background: This is a outdoor grow out in the forest with three different strains.

After germinating the first four weeks of growth went normal, maybe a little bit slow due to cooler nights but no major problems, then once transplanted I went to visit the plants which by now are about 8 weeks old and found them severely stunted, all 50+ plants were 2 foot tall or less.

Now my first guess is the cooler nights 14°C - 15°C in the first four weeks stunted their growth even though the first four weeks growth was relatively normal, or maybe it was the day/night temperature fluctuations 21°C - 23°C (day)/14°C - 15°C (night) caused the stunting or a combination of both?

Another guess is I am growing in a pine forestry block so the soil is most likely acidic, could that have something to do with it?

Just trying to find the reason because this is my third failed season in a row, although the failures are unrelated to each other.

 

[Phytoplankton]

Not familiar with your soils, but in general, pine forest soils are poor soils, with most of the nutrients in the top couple inches of the soil, I’m sure there’s probably exceptions, you might want to do a slurry test on the soil. Also, how is the drainage/compaction on the soil? Grassland soils are usually better, but then your grow isn’t hidden.

 

[Phillybonker]

Not familiar with your soils, but in general, pine forest soils are poor soils, with most of the nutrients in the top couple inches of the soil, I’m sure there’s probably exceptions, you might want to do a slurry test on the soil. Also, how is the drainage/compaction on the soil? Grassland soils are usually better, but then your grow isn’t hidden.

To be more accurate, half my grow in a pine forestry block and the soil there is bare (no vegetation) so it's quite dry and probably not a lot of worm life. The soil in this location is quite compact and drainage is not a problem as these plants are on hills.

The other half is in another pine forest block that is overgrown with gorse and reeds and the soil is very dark so it should be in good condition. The reeds look like they have doubled in height since I last visited four weeks ago which is another sign the soil is in good condition. However it is still a forestry block so the soil could still be acidic, I'll buy a pH tester for next time I go visit. The soil has good drainage and good structure (not too compact, but just normal).

But here is the other thing, I also have six plants growing in a different location close to a beach with the "soil" (if you can call it that) being 70%-90% sand, I don't water them at all and they have to fend for themselves, surprisingly they are doing the best out of all my plants although these are also badly stunted.

 

[Joe Brewster]

Add wood ash to lower the acidity of your soil

 

[Phytoplankton]

My guess is that the soil is your problem. The bare pine forest soil probably has little or no nutrients in it and if it’s a compacted soil the roots are probably having a tough time penetrating it. I don’t know about your area, but in mine, any soil growing reeds is usually dark, damp/wet, and has lousy drainage. Those conditions are usually not great for cannabis. I always brought in soil for guerilla grows.

 

[Phillybonker]

Add wood ash to lower the acidity of your soil

Alright, I'll give that a go.

 

[Joe Brewster]

Alright, I'll give that a go.

Also adds P & other nutrients

 

[Phillybonker]

My guess is that the soil is your problem. The bare pine forest soil probably has little or no nutrients in it and if it’s a compacted soil the roots are probably having a tough time penetrating it.

I did add blood & bone when I transplanted but the semi-compact soil would probably limit the plant size even if there was another reason for the stunted growth, I knew that when I planted them but I was running out of time to find grow spots so I just had to settle for whatever area I could find to dump some plants in the ground.

I don’t know about your area, but in mine, any soil growing reeds is usually dark, damp/wet, and has lousy drainage. Those conditions are usually not great for cannabis. I always brought in soil for guerilla grows.

It's not really reeds, I chose the wrong word, more like long grass that can grow to a metre tall. And I reckon the only possible issue this soil could have is maybe being too acidic being a forestry block and all.

Just reading up on sandy soil apparently that can be quite acidic as well.

 

[Phillybonker]

Also adds P & other nutrients

Yeah I added blood & bone, this one is 10 - 4 - 0.2

I've got to throw down some potash next week and I'll also add dolomite lime as well.

 

[Phillybonker]

Also I forgot to mention in the first four weeks after germination although night temps were usually 14°C - 15°C occasionally it could dip down to 12°C - 13°C, I estimate this would happen around one out of four nights.

 

[Joe Brewster]

Yeah I added blood & bone, this one is 10 - 4 - 0.2

I've got to throw down some potash next week and I'll also add dolomite lime as well.

Wood ash is an excellent source of lime & potassium for your garden. Not only that, using ashes in the garden also provides many of the trace elements that plants need to thrive.
Plus wood ash is free