Re: How tight should soil be compacted

On 17/10/2021 05:56, bob prohaska wrote:
> In rec.gardens John Robertson <[email protected]> wrote:
>> I'm not a gardener but I planted some seeds of food eaten from the kitchen
>> (pears, apples, lemons, oranges, avocados, watermelon, pomegranate, etc).
>>
>   
> Those seeds all have fairly different germination techniques; for example,
> avocado pits are commonly sprouted in water. Sounds like you're experimenting,
> to see what grows and what doesn't.
> 
>> I put the soil in typical plastic plant containers but I don't know if I'm
>> supposed to pack the results tightly or loosely or mediumly. If I pack them,
>> with a mallet I can easily triple the amount of soil and even if I compact
>> them with my fist, I could easily double the amount of soil, so compaction
>> certainly makes a huge difference in soil volume.
>>
>> There must be an optimum amount of compaction though, for soil volume and
>> for water sponging I would think that the experts already know about.
>>
>> What's the rule on compaction when you dig the soil out of the ground with a
>> shovel and then when you fill a dozen of these quart to half gallon sized
>> black plastic planting containers?
> 
> Depends on the seeds, soil and importance of success. If you're using
> natural soil you might let water do the compacting. Flood the pot of
> soil, push the seed into the resulting mud and flood the pot again.
> That's how nature compacts soil and will give some hint how the seeds
> might fare on their own in your area.
> 
> If you really want the seeds to grow, David's approach is customary.
> There's much less risk of waterlogging if you use a porous mix, pack
> it till it's just immobile when flooded and make sure all liquid drains
> in a few minutes. Very few seeds will germinate if submerged.
> 
> I think waterlogging is the biggest objection to using natural soil
> in pots. It's too easy for the water to get trapped in the pot,
> especially if the pot is plastic.

Waterlogging and/or drying out are the two commonest reasons for 
germination failure. It doesn't matter what soil or compost you use, or 
even how compact it is, if you follow this guidance:

Put the soil/compost in the pot. If using soil, just fill to within 1/2" 
of the top; if using compost, fill to the top and press down 1/2". Put 
the pot in a bucket and fill with water to the soil/compost level. Leave 
for an hour (some peat-based composts, if dry, can be very slow to take 
up water again. A drop of washing-up liquid in the water can help). 
Remove pot and allow to drain for 15 minutes. Add seed(s), and either 
push into the compost until well covered or place on surface and cover 
with a little moist compost. Put pot in a polythene bag and seal the 
bag. Just keep an eye on the pot every week or so to see if germination 
has taken place. With the bag sealed, you won't have to worry about 
under/overwatering. Once germination has taken place, remove the pot 
from the bag.

-- 

Jeff