Update on Sterilizing Soil

We purchased a new microwave.  

No I did not bust the other sterilizing soil.

So this time I went 4 minutes.

The temperature reached 198 F, just under the toxic level all the references say you want to stay away from.

I wrapped my little bundle in a bathroom towel and took its temperature every 10 min.

10 min   188 F

20 min   178 F

30 min  170 F

I'm starting to see a pattern.  I'll leave the little baby wrapped for the afternoon (at least 2 hours), then I'll unwrap and let it cool.

I'm seeding tonight so I will add to this post later on, the quality of the germination.  I'm itching to plant my tomatoes but I think I'll wait another week.

Seed Starting Time, Again

     Seed starting time again, that time of year comes around pretty quickly.  The days are getting milder, snow melting, the sun warmer and the bulbs are peeking up through the snow.

     I reuse soil all the time, mix in some old with some new and pot up plants I have divided in the garden.  But I won't reuse old soil for seeds and seedlings and I am even careful if I have a half used bag of potting soil left over from last year.  Up until a few years ago, you could purchase a fungicide called Damp-Off that you added to your water when watering in your seeds and watering your seedlings that prevented the damping off fungus that devastated your newly emerged seedlings.  That is no longer on the market and there is no equivalent product that can be used, not even organic (please tell me if you know). 

     There are antidotal remedies, hydrogen peroxide, chamomile tea (probably puts them to sleep), cinnamon (at least it makes the soil smell good) and powdered charcoal, that are 'supposed to' prevent the dampening off.  Water your seedlings from the bottom (good advice) and give them good air circulation (more good advice), but the best advice is to use good sterilized potting mix. Most mixes are pre sterilized, but what if you have leftover potting soil from last year.  But remember seed has become expensive.

     There are a few ways of sterilizing your soil, all involve cooking (technically).  Get out your measuring spoons and scales.  You can use a pressure cooker, steamer, oven (every reference says this will absolutely stink up your house) or your microwave. 

     I used the microwave method last year with really good results (at least no damping off) so I'll try it again.  This method is all over the Internet, it must have come from one source and I have not seen anybody saying it doesn't work.

     Add enough water to the soil so that when you squeeze the soil, a bit of water comes out. 

     Place 2 lbs of this mix in a Ziploc (or equivalent) bag, or deadicated microwaveable container and place it in the microwave with the top open.  Make sure it is stable.  The last thing you need is to clean potting soil out of the microwave.



     All references I found said to microwave for 2.5 minutes / 2 lb.  My scientific mind questioned this since everything I read referring to the oven method was to maintain the soil at 180 F for 30 minutes.  Even if you are microwaving, should not the soil temp hold at 30 min also?   Does it even reach that temperature? Soil temperatures should reach at least 180 F but not more than 190 F.  Many references refer to toxicity to the seeds if the soil goes above 200 F.

     I have a soil thermometer, very useful for checking the garden soil in the spring and extremely useful in this application.  After 2.5 minutes I resealed the bag with clothes pins and the thermometer and took a reading.

     The temperature of the soil only went to 160 F.  Time to do a few more experiments.  I microwaved a new batch (room temp) for 3 minutes.  It just barely reached 180 F.  One more time.  3.5 minutes brought the soil to 188 F but the soil temperature dropped below 180 within 7 minutes. 

     I'm going to use it anyway, because  I am quite confident in my soil mix and this was just extra insurance.  If I was at all concerned, I would buy a small bag just for seeding or do more experimenting to get it right.

     Next time I need this soil I may try 4 minutes and try to insulate the bag by wrapping it in a towel or something similar to keep the temperature up for a longer period.  Just a thought. 

Now a tip for seeding. 

Those containers that mushrooms come in, great seeding trays. 

All you need to do is poke a few holes in the bottom and they are recyclable too.

Happy Seeding!



Winter Hardy Cactus Varieties

     So this picture of cactus must have been taken in the southern US.  Right?  Wrong.  This was taken at the Nova Scotia Agricultural College in Truro NS.  Although not native to the region, there are no native species east of Ontario, they absolutely thrive here.  Around here winters can go 20 below Celsius.  No problem for these cactus.

     This is my last posting on cactus (maybe; for a while) and I want to highlight some cactus species that will grow here in our province and some I am currently growing.  I have given you the background on culture, propagation and care.  Now what varieties are available.



     Opuntia humifusa also known as O. compressa is a large Prickly Pear Cactus found in Southern Ontario near Lake Erie. it is an endangered species found only in 2 small locations near Point Pelee, Ontario. It is one of the most hardiest of all Prickly Pear Cactus.  For me though, I have yet to get it through the winter in my cactus bed.  Other people in the area have, and have had no problem.  It is one of the most prolific bloomers and grows quickly with very large pads.  The flowers are yellow to yellow gold.



      Opuntia macrorhiza is winter hardy to zone 3, keeping in mind good drainage.  It is the only Opuntia I have that is not native to Canada.  The plant is 6-12" in height about the same as O. humifusa.  It is native to the central and mid-west US through to the south.  It tends to be different from O. humifusa with thicker roots, more spines and those spines tend to be slightly curved (that does not make them any less lethal).  Most O. macrorhiza are yellow blooms.  This variety that I carry, O. macrorhiza v. macrorhiza has a red centre that radiates outward.  Clumps can spread out over 2 feet.

      Opuntia polyacantha probably have the largest collection of hybridized varieties available.  One of the most notable is 'Crystal Tide' which  are porcelain white with red stamens and yellow pollen, but may other varieties range from yellows to pinks to red and anything in between.  Some varieties are quite small where as some get to 3' in diameter.  O polyacantha is winter hardy to zone 3 yet curl up and look almost dead in the winter. It is native to central - western US coming up into southern Alberta and Saskatchewan. It is know as the Plains Prickly Pear and can be cold hardy to Zone 2.

     Opuntia fragilis; the Brittle Prickly Pear.  According to the literature, it is the most winter hardy of all the Opuntias, found as far north as the Artic Circle. They do not have large pads like the traditional prickly pear cactus but small 1-2" oval pads with spines that can be longer than the pad.  They are very abundant at producing new pads and it has, as the name suggests, the ability to propagate itself prolifically. You don't need tongs and a knife to separate these guys (well maybe the tongs).  The flowers are large and yellow with either creamy green or red centres.  They flower sporadically.   They are found from BC as far east as the Manitoba-Ontario border and down through the central US.

     Opuntia rutilans' pads are shaped like sausages, they can be about 4" long and up to 1.5" thick.  This is one of the few prickly pears that have very few spines, usually at the tips.  Flowers are deep pink with extra petals, 3" across.  Mine has yet to bloom.  I am patiently waiting.... It grows rather quickly and can become quite a good size in a short period of time.





     Escobaria vivipara also known as Pincushion Cactus, Beehive Cactus, Ball Cactus and probably quite a few other names.  It is found in both Manitoba and Saskatchewan.  It is a nice ball shape, holding its form through out the winter surviving winters at - 30 C.  Beautiful pink blooms are formed in June at the apex of the cactus.  It propagates itself  by producing babies around the base of the mother cactus.  These maybe detached, allowed to dry and then planted like the Opuntias.  The Escobaria in the picture above bloomed two years in a row and got to a diameter of 5".  The winter didn't kill it, someone drove over it with a car.  Who??  At least I had some babies in the Greenhouse.

     Another one I have are Echinocereus, Claret Cup Cactus.  No pictures at this time and no commentary, can't find them.  I know I took pictures and I was just researching them last month.  Can't find the notes.  I have wasted 2 days looking for them and I can't wait any longer to post this.  Echinocereus will be introduced at a later date.

They may be a bit shy.