A Few Questions

[ali]

hey guys, i've got a few questions:
1. what does happen if seeds sown in high temperature (about 40 C )?
2. is day and night temperature differences important for germination ?

tnx

[Hardy_whv]

Hi!

1. what does happen if seeds sown in high temperature (about 40 C )?

I've seen a couple of studies about the germination process of cacti seed, but they only looked at temperature ranges between 10 and 35°C. For most species the germination rate deteriorated above 30°C, but some species preferred temperatures between 30 and 35°C. (There was the general tendency, that higher temperatures speeded up the germination process, but had a negative impact on the germination ratio.)

I assume there are some species that will germinate at 40°C, but the majority of cacti will not germinate at all at those temperatures. (i.e. some Pedicactus are known to like hot tempertures for germination.)

2. is day and night temperature differences important for germination ?

It's often said that lower night temperatures increase the germination rate, especially for cacti from high mountain regions. The studies I've seen do not support that statement.

I always provide lower temperatures at night for my sowings, but I have not tested whether this really makes a difference.


Cheers,

Hardy

[Peterthecactusguy]

Desert cacti seem to need the higher day time/lower night time temps as well. The reason is because in the natural desert the temps are very different during the day and at night. Where I live in the desert we have day time temps around this time of the year about 110F (43C)and at night they go down to around 60F (16C) as you can see that is a large range in temps and are averages. Yesterday it was about 105F (40) and went down to about 65F (18C).

That is one thing to keep in mind. You have to look at the natural place where the cacti live and grow.