Germinating Aloe polyphylla - An Alternative Approach

In an earlier article, I posted the method given to me by the South African grower of my original batch of seeds.  Here they recommended 1 or 2 cold periods followed by a warm period to break the dormancy.

Since then I have been trialling small batches of the seed in order to test other methods or to prove that one.  Using the double dormant method, I was seeing around 50% germination - very uneven though and taking many weeks were the chances of getting a fungal infection on the seed was very high, especially given the removal from sale of most of the effective seedling treatments.

This season, I was lucky.  A grower in the UK who had seed from my orginal certified batch, was able to offer me in excess of 3000 seeds from his own plants that he had hand pollinated.  Armed now with a surplus of seed I may not be able to sell in a single season, I decided to to try a more radical method I had read about.

The seeds - in my case 30 seeds (1 percent of my stock) get put in cool water.  A jam jar in my case, in my kitchen on a granite worktop which sits at an even 12 Deg C.  At first the seed floats, this remains the case for the next 6 days, then they start to slowly sink.

Between 12 days and 14 days the first seeds germinate - by day 16 I have four potted up in compost and put in the warm in one of my mini propagators.  By day 24 a further 6 have germinated  and then by day 30, all the seeds are showing signs of growth. 

So I now have 30 seedlings - of course they are very small, a single leaf and a single root, so the trick will now be to keep them going until I get a second/third leaf and I can breathe a bit more easily around my delicate and valuable charges.

I really did doubt that this method would be as successful as the fridge method, after all, it doesnt seem to make a lot of sense - until you consider how wet and cold it is in their home on the mountains of Lesotho.  The germinate on steep slopes in the cold and very damp grass in their homeland, so why not in my kitchen given a similar treatment.  This avoids having the seed dry out (fatal), the introduction of fungal spores (almost always fatal) and the rapidly changing condtions on the surface of the soil in a propagator (often fatal).  So 30 seeds, now 30 seedlings - it will be interesting to see how they grow from here on in.

So for the instructions:

1. Clean jar
2. Cold water
3. Seeds on top of water, place some where cool and even temperature, around 10 - 14 C
4. Stir seeds daily, change water every 3 or 4 days
5. Once they sink, change the water.
6. From day 10 watch for a little green leaf out of the seed or perhaps a white root
7. When you have a root and leaf, pot up in cactus compost and continue to grow bright, warm but shaded from full sun.  Do not let it dry out, do not overwater it.
8. In a few months the new leaves will show and by 6 months to 18 months you will see the spiral form (clockwise or counter clockwise).
9. In 6 -7 years your plants may flower and if you hand cross you will get seeds that are worth a small fortune (quite literally thier weight in gold).

Soil Mixes

One article that was on our old website, concerned soil mixes.  Unfortunately I was not able to save that post, so thought I would take the time to re-write and update it here, especially as  it is the time of year when most of the germination is done.

 

Seed Sowing

For seed sowing we make our own mix based upon a peat base (from sustainable sources) with the addition of various components according to what we are doing with it.

Initially riddled at 7mm, in order to remove the larger pieces from the mix (these are not wasted, we use it to mulch round our garden plants).  To this sieved mix we add 1 part sharp sand, 1 part vermiculte and 1 part perlite for every 7 parts of the peat base.  This gives a 7:1:1:1 mix, which is open (for good root development of the seedlings) but also moisture retentive (to help with the intial germination). Unless we are dealing with finicky seeds, we no longer sterilise.  Where we do sterilise, we do so after the seiving stage and only to the peat base as the other componenets are naturally sterile.

Growing On.

Same mix ratios, but we do not seive this mix, preferring to just pick out the larger unwanted twigs and branches so common in commercial peat based mixes (likely due to bulking out with coarse shredded material

Specialist Mixes

Cactus and Succulents get extra drainage material so the rations go down to 4 parts peat base to give a 4:1:1:1.  For seed sowing here the riddle gets set at a much finer 4 mm.

Sterilising

To sterilise the mix, we use the oven tray method - basically put the mix in an oven proof tray (it must be damp for this to work quickly) and then place in an oven at least 150 Deg C (300 F) for an hour.  The steam produced and the heating of the centre will serve to kill all weed seeds and pathogens in the mix.  Allow it to cool covered, so no new pathogens are introduced, then re-wet it (so that it is damp) just prior to use.  Small seeds, where the resultant seedlings could be swamped by weeds or other unwanted growth, will especially benefit from this.   Dont be fooled into thinking that shop bought mixes will be free from problems, they never are.  You have no idea where they were mixed or how long they were standing in the yard or shop - all would be a source of problems and the only way to be sure is to sterilise.   Smaller amounts can be microwaved on 75 - 100 % power for around 15 minutes or so per 2 litres of mix.

Diatomaceous Earth (DE) - Organic Insect Control

Diatomaceous earth (DE) is a non-chemical pest control agent which uses a 'mechanical' action to which no resistance can ever be developed by the pests it works on.  DE is a fine powder, derived from the sediment of ancient freshwater lakes which contain the remains of simple organisms known as diatoms, which have a silica based 'skeleton'.  It is these fossilised, skeletal remains that provide the pest control as these microscopic shards of silca are deadly to the pest, but completely harmless to humans.  To the insect or mite, it is akin to crawling across a surface covered with broken glass, the shards pierce or damage the skin of the insect, even those with hardened carapaces as they all have weak spots at the joints etc.  Once pierced or otherwise damaged, the 'victim' dehydrates quickly, assisted by the absorbant nature of the earth, and dies. 

Red Spider Controlled by DE on Alocasia leaf

It is effective against insects, arachnids and acarids (mites), including their larva (but importantly not their eggs, so repeat applications will be needed to control a population that has already started the breeding cycle).  It is not harmful to earthworms as it only works when dry. It should not affect larger winged insects (Bees etc) as they would have to fly through clouds of it to have any adverse effect. It works at any temperature, unlike organic biological controls, and can be applied before any pests are spotted so as to reduce the chances of damage occuring before you spot the pests.

It is probably the only reliable method of controlling the 2-spotted mite (aka Red Spider Mite), but works on almost every single garden or glasshouse pest. Other pests that can be controlled are aphids, thrips, whitefly (adults), mealy bug, Lily beetle, earwigs, all other mites, cockroaches, sciarid fly (and larvae) and many others. 


For horticulture, there seem to be 3 methods to apply your DE.

1. Puffer bottle or dispenser to literally puff a fine layer of DE on to the target area - which should be dry as this will only work when dry - try to avoid large clumps or thick layers on plants as this is wasteful and can slow down photosynthesis (which would weaken the plant)
2. Make up or soft paint brush, which can be dipped in the DE and then brush it or flick it on to the target area - this method is wonderful where aphids are clustering on stems as it allows you to target the groups of pests whilst keeping the DE away from beneficial insects.
3. Dissolve 15 grams of DE in one litre of water (add the DE to water and shake well).  Spray on the affected plants so as to wet them, but not so that it runs off.  Allow to dry and it will give a very thin but even coat.

Whichever application method you use, bear in mind that it only works when dry - so if you wash it off when watering or the rain removes it, you will need to re-apply it.  If you can see the DE on the plant, then it is still working, if you cannot see it, then you will need to re-apply.

Once you have killed off the pests (can take 2 or 3 applications to catch all generations and prevent re-population), you can then discontinue its use until you notice pests again.  
Because the DE is food grade there is no minimum interval between application and harvest.  Just wash fruit and veg as you normally would.

If you apply a lot of DE or have any respiratory issues then you should wear a face mask when using it dry. 

There are hundreds of uses for DE, here we are just describing methods to control pest in horticulture.  A rule of thumb application rate for control would be around 2 - 4 grams per square metre of leaf surface being covered at each application - this amount will remain effective until it is removed by rain or watering.

Why Not To Give Up On Seeds You've Sown

Weather has picked up, the greenhouse is getting warm during the day, so thought it was time to start repotting last years seedlings.  We started mist spraying the pots around the end of January to get the roots going on the succulents, which includes several pots of Agave seedlings.

Today as I potted up some Agave americana, here's what I found...

 New seedling to left of year old Agave americana

The new seedling, still with the seed case on the tip of the seed leaf, had germinated almost a year after the original sowing back in Spring 2018.  2 more were found in this state.  It just shows you should never give up on seeds in a pot, especially in the case of succulent plants where not all will germinate at the same time as a defence against poor growing conditions during any one season which would otherwise spoil the whole crop.