This is how I rooted tens of Guava cuttings this winter/spring:
What you will need:
a. Guava cuttings
b. Peat moss
c. Perlite
d. 2 clear plastic cups of the same size
e. 1 painted or covered plastic cup of the same size as the 2 clear cups (I warped a clear cup with black electric tape)
f. Heating mat (with thermostat)
My Method:
1. Prepare a potting mixture of 60% peat moss, and 40% perlite. Pre-moisten the mix;
2. Clean the cuttings then dip them in diluted clonix (1 parts clonix 1.5 parts water);
3. Drill 4-5 small holes on/near the bottom of
one of the clear plastic cups;
4. Fill 1/3 of that cup with the potting mix. put one guava cutting in the cup and start filling the area around it with potting mix until the cup is almost full. Press lightly on the potting mix and add more if you need;
5. Put the 2nd clear plastic cup on top of the first cup to make a green house like dome. Use a tape to securely attach them together. Don't make holes on the 2nd cup;
6. Insert the bottom cup into the painted/covered cup. this will keep light from getting to the soil (roots don't like light);
7. Put this on a heat mat set to 77-68f degrees (25-25.5c); [you can use another cup with potting soil (inserted into a painted cup) to stick the thermostat in if you need];
8. Leave them be for about 3 weeks. After that, you can check for roots periodically by simply removing the painted/covered cup. Very simple.
Mine rooted within 3-6 weeks. I have about 60-65% success rate using this method.
Another method I have used with slightly lower success is a bit more difficult as it requires a lot of DIY. I 'll share it if there is enough interest.
Pictures:
Setup before inserting it in a covered cup
After inserting in a covered cup
The result
Amazing roots
I hope this method works for feijoas