Sowing in Depth of Winter

Now that the days are starting to get longer, our thoughts turn to summer and growing plants.   Whilst it is possible and indeed in some cases desirable to sow early, this is not the case for the majority of seeds unless we take additional steps.

Warmth

For any seed to grow, one of the triggers in warmer weather.  So sowing in winter requires the use of bottom heat.  A propagator (with or without thermostat) or a heat mat is ideal.  Over a radiator is not a suitable environment unless its all you have got.  Most radiators sit under windows (most of mine do) and the temperature above the radiator can be too much when it is on and nearer the glass far too cold.  The 'goldilocks zone' can be as small as a few cm wide in the middle of that area, hence why we cannot recommend this.

Light

The increasing days will provide this for your seeds, especially those that are sown on the surface and need light to germinate.  Avoid South facing windows at all costs, if this is all you have, set the trays and pots back a metre or so, this way you diffuse the light a bit and avoiding the thermal effects of full sun.

Another way with light, is artificial lights.  Whether this is a standlight or a hanging light, it must be full spectrum or a specific growlight designed for the purpose.  LED versions of these lights may sit just a few centimetres above the seeds, as their main output is light. Sodium or other metal halide lights should be sat well above the tray as most of their output is heat.

We use the LED types on pullies sat above the seed trays so we can adjust the height. Inside a mylar grow tent, little additional heat is required apart from a heat mat to warm the soil.  Most of our out of season testing is done this way so that we can check the seeds first before the main growing season.

Our entire set up uses around 300 watts for 12 hours a day and 80 watts for the other 12 hours.  With this we can have up to 24 full sized seed trays, although we rarely fill it if we intend to grow the seedlings on for our own use.

Growing On

Don't forget about the space you will need for growing on and where you intend to do this.  The temperatures here can and indeed should be lower than those used for germination.  The amount of light required will increase too, but never be tempted to place them where they get full sun.  Even cacti will scorch and die if subjected to full sun as seedlings.

We sometimes use the grow tent to bring the seedlings on fast.  This works well for the stronger growing perennial types, especially Agaves, Aloes and relatives.  We also grow chillis (when we have space) under this set up, being able to keep 4 to 8 plants and bring them into fruit as early as June.

Growing Solanum Species From Seed

Solanum, the species rather than the hybrids can be best thought of as 'proto' tomatoes.  Thats not to say they will germinate as easily as tomatoes, they won't, but in essence they need very similar growing conditions.

Myth 1

They are tomatoes arent they, they will germinate rapidly and easily if I just sow them like tomatoes...

 

No they wont, they will sulk and languish in the soil and may not even sprout the first year if you just do this.  They need pre-treatment, a good soak, preferrably in Salt-Petre solution, but warm water if changed a few times is almost as good.

 

Myth 2

They are annuals, so they will crop the same year no matter what.

No they arent. They are perennials, they will crop the same year from an early sowing, but if sown later, then they should be overwintered frost free and will crop well in subsequent years.  Early sowings may need extra light, they certainly need extra warmth, but if you cannot do this, then sow them later and accept they may not produce fruit in the first season.  The chances are they will flower the first season, but any fruit set may or may not ripen before the shorter days put paid to that.

Pre-treatment

Soak the seeds in warm water, with or without salt-petre, but if it is just plain water, change it every few hours. 

Sowing

Sow on the surface of a good quality seed raising mix and lightly covered with the mix or with vermiculite.  Water once, then place somewhere warm, close and light.  Temperatures of around 24 - 28 Deg C work best, much cooler and they wont germinate, much warmer runs the risk of the soil drying out leading to a crop failure.  In ideal conditions they may take up to 6 weeks or more to come up - see they are not 'tomatoes' (even though by Genus they are).  The germination will be sporadic and uneven, which is a natural defence against a crop failure due to adverse natural conditions such as a drought...

Growing on

Grow on like tomatoes, you can grow them in pots till they are big enough to go in a grow bag or larger pot.  If in a growbag, you will need to transplant it to a pot for overwintering as the growbag will subject the roots to too much cold possibly killing your plant.

 

Feed with a tomato fertiliser  and when the fruit has set, double the amount.  Germination to first fruit can take up to 8 months, so be patient the first year.

Seed Growing Keys

When looking at growing seeds there are many keys to success.

In a lot of cases there are rules of thumb that will give you a degree of success providing you provide the basics.   

• Seed (must be viable) and prepared correctly
• Pre-treatment (where needed)
• Soil
• Light
• Warmth
• Water
  
• Time of year (Season)
  
• Germination Time
  

 

One of the most neglected basics is time of year.  Unless you can provide year round light, warmth and care, do not sow seeds out of season.  Another one is patience.  Seeds do work to a clock, just not yours.  If you dont allow sufficient time or you are impatient to get going, then you will not have a lot of luck with seed growing.

Season

Season, or more properly growing season, is taken to mean when the soil is warming and the days are lengthening towards the summer highs.  Indoors this means anytime after the winter solstice, as the days are lengthening nicely for the seedlings to subsequently grow away.  Outdoors it is when the soil is sufficiently warm for seeds to come up (rule of thumb, if you see weed seedlings coming up, its time to plant your seeds).  Yes some seeds can be 'tricked' by artificial heat or artificial light, but not all can often appearing to have inbuilt calenders and will only germinate at a certain time of year.

 

Timing

The time it takes seeds to germinate varies wildly. In some Cactus this can be a little as 18 hours, in some plants such as palms and hardwood shrubs in can be up to 18 months.   There are things you can do to speed things up, but where a minimum time is quoted, this is the minimum for treated seeds.  There is no point expecting anything before that point, or being disapointed if you have to wait till the maximum time.  Thats just nature, so work with it, not against it.  Rule of thumb - never give up unless you can see that the seeds have clearly failed - ie they have rotted.

 

Growing Annuals and Biennials - A Reminder

If your seeds are for the garden, this year, then likely they are either annuals, are treated as annuals or are short duration perennials (or even biennials).

Nearly every single species will respond to the the 'sow and grow' method.  Sow the seed, barely covering it, where it is to flower or in small pots, water it and let nature take its course.  Some will need warmer weather, some will need time to take up water and then germinate, but all will respond, in time, to the 'Sow and Grow' method.

Anything not falling into this category will have its own page somewhere in the blog.

How To Use This Blog

Tagging and Searching

This blog should be correctly tagged with the latin names of all of the species we sell online, HOWEVER, should a search not return a post or even several posts, then you will require the generic instructions which can be found here:

 Instruction Basics

Note that the instructions specify times for the seeds to germinate.  These times are the minimum provided all of the cultural conditions have been met.  If seeds are too wet, too cold, too dry, too hot, sown too deep, not prepared (should the instructions call for that) then success is not guaranteed.  Seeds are living things, they require a set of conditions in order to perform as expected, some are forgiving, some, unfortunately, are not.  Work with nature, not against it, be mindful of the time of year, especially with short duration plants.  If now is not the right time, wait, we only sell orthodox seeds which gives them a shelf life that at the very least extends into the next season, so you may be best off waiting.  If you cannot provide extra light, do not sow seeds in the Autumn/Early Winter.  Extra light means growlights.  If this is not possible then do not sow until the days are getting longer, so after the winter solstice.

Growing On

We dont always include growing on instructions, but there are several rules of thumb with this.  When you feel you can handle a plant, then you can pot it on from the seed container into a small pot to start with.  Once the roots fill that pot, again move it on, one or two sizes up.
There is a wealth of information out there on growing plants and seedlings to maturity, far more than this blog could ever contain. 

Recycling

In line with the trend towards maximum recycling, we have for years used packaging that is fully recyclable.  The Mailers, the invoices, the seed bags themselves can all be recycled.

The paper we use comes from companies that use recycled content and no bleaches when producing it (so no bright white paper).  The mailers can be fully recycled, many have diagrams on them as to how to do this.

Recap of Sowing Guides

Due to the run we have had on the online shop lately, I thought it would be prudent to give a recap of where the instruction sheets can be found.

For Sweet Peas, follow the pea seed instuctions to be found here  We recommend either a hot water soak or nicking the individual seeds (time consuming) and then soaking in tepid water.  Either/or not both.  Soak until the seeds swell to around twice the size before sowing.

For Nasturtiums, they may be sown directly where you want them to flower (2 seeds together, remove the weaker seedling) or so individual in cells or small pots and grow on before planting out.  For direct sowing wait till April (after Easter for this year), otherwise start now.  We have found soaking the seed speeds germination, but it is not necessary.

Marigolds - sow thinly just below the surface, they need a bit of warmth to germinate and should come up in around 2 weeks.  Once they are up and they are big enough to handle, you can thin them out, repotting those you thin so as not to waste plants.  The should be grown on warm and bright, remember these are from Mexico originally, so they love warmth.

Snapdragons - thinly sow just barely covering, they need to be around 15 Centigrade to germinate and should come up quite quickly.  They will grow quite quickly and should be thinned out to avoid weak seedlings.

Stocks (both Night Scented and Virginia) - thinly sow where you want them to flower, do not thin, they grow best in clumps and drifts.

Alyssum (Lobularia) - thinly sow barely covering as they need light to germinate, they may be sown in trays and pots now or later where they are to flower.

Cosmos - sow thinly barely covering,  they should be sown where they are to flower or in pots to be planted out later, do not thin, they use one another for mutual support, spaced too widely they will flop over.

Petunias, sow thinly on the surface of seed compost.  When large enough to handle, prick out into trays or pots, spacing them out to give them growing room.

Temperature - most of the above will germinate as long as the temperature is over 16 Deg C.  All will do better, slightly warmer.

Humidity - seeds dont like drying out once they have been wet to the point of triggering the germination processes.  Best way to ensure this is to cover the trays - as most like light to germinate, plastic is best for this purpose (we use freezer bags on our pots - saving them afterwards for next year)

Germination Updates

This update covers the use of a Salt Petre (Potassium nitrate - KNO3) in respect of seeds that are stubborn to germinate or germinate in an uneven fashion.

The tests were conducted on open pollinated chilli seeds, specifically the superhot variety Capsicum chinese 'Bhut Jolokia' aka the Ghost or Naga chilli.

Notoriously tricky to get even germination, if any on this type, I tried one batch of 30 or so seeds in late January in ideal conditions but with no real pre-treatment.  It was sown along other types including Padrons, Cayennes, Scorpions and Reapers - the last two also being noted as possibly tricky.

After 7 days, all pots had at least one seedling, by 14 days the other types had 10 - 30 seedlings with an average germination rate of 90%, except the lonely Bhut Jolokia seedling.  Finally by day 28, it was joined by one more seedling for a total of 2 from 30.

At this point, I decided to get the rest of the batch going, but I soaked the seeds for 12 hours in a solution of salt petre (5g per litre) from the batch we sell online in 5g packs.  They were then sown in identical conditions for germination and the picture below was taken just 24 hours later.

For reference, the seeds were planted in 6 columns of 5 seeds, for a total of 30 seeds.  The image shows many coming through and movement of soil in all columns in all seed positions.  3 days later all the seed leaves had opened and there were 30 healthy seedlings.

The bottom line is this stuff really works, so I then tried it on all the remaining chilli seeds that I wanted to sow this year with the same stunning results.

2020 Germination Test Results - Round 1

First test results are in for the year and so far all looks good.

Acacia (43 Species)

Results

All this years seeds, minimum 90%, maximum 100%, average across all batches is 97%

Context

Batch Sizes - 10 seeds
Earliest 1st germination 5 days
Latest 1st germination 14 days
Bottom heat 10C lift
Daytime Air - 19.5 C
Nighttime Air - 16.5 C
Bright Filtered Natural Daylight

Agaves (31 Species)

Results

All this years seeds, minimum 90%, maximum 100%, average across all batches is 95%

Context

Batch Sizes - 25 seeds
Earliest 1st germination 3 days
Latest 1st germination 21 days
Bottom heat 10C lift
Daytime Air - 25 C
Nighttime Air - 20 C
Lighting, shaded full sun equivalent

Cacti (71 Species or Mixes)

Results

All this years seeds, minimum 85%, maximum 100%, average across all batches is 95%

Context

Batch Size - 30 seeds
Earliest 1st germination 3 days  (Astrophytum as expected)
Latest 1st germination 21 days (Wittia & Epiphyllum as expected)
Bottom heat 10C lift
Daytime Air - 25 C
Nighttime Air - 20 C
Lighting, shaded full sun equivalent

Aloes (16 Species)

Results

All this years seeds, minimum 85%, maximum 100%, average across all batches is 97%

Context

Batch Sizes - 20 seeds
Earliest 1st germination 5 days
Latest 1st germination 12 days (Except polyphylla)
Bottom heat 10C lift
Daytime Air - 25 C
Nighttime Air - 20 C
Lighting, shaded full sun equivalent

Pachypodiums (6 Species)

Results

All this years seeds, minimum 85%, maximum 100%, average across all batches is 90%

Context

Batch Size - 20 seeds
Earliest 1st germination 7 days
Latest 1st germination 21 days
Bottom heat 10C lift
Daytime Air - 25 C
Nighttime Air - 20 C
Lighting, shaded full sun equivalent

Rudbeckia (4 Species)

Results

All this years seeds, minimum 74%, maximum 92%, average across all batches is 89%

Context

Batch Sizes - 100 seeds
Earliest 1st germination 5 days
Latest 1st germination 14 days
Bottom heat 10C lift
Daytime Air - 19.5 C
Nighttime Air - 16.5 C
Bright Filtered Natural Daylight

Stapelias (2 Species)

Results

All this years seeds, minimum 95%, maximum 100%,

Context

Batch Sizes - 20 seeds
Earliest 1st germination 1 days
Latest 1st germination 2 days
Bottom heat 10C lift
Daytime Air - 25 C
Nighttime Air - 20 C
Lighting, shaded full sun equivalent

Growing Capers From Seed

Pre treatment

Caper seeds need to be soaked in luke warm water for 48 hours before anything else, then they need to be stratified at 4 Deg C for at least 4 weeks.  See the post on stratification here

Sowing

Sow the seeds in a good quality seed mix in pots covering the seed with about 4mm of the mix.  Water well and then seal in a plastic bag and place somewhere warm and bright until they germinate.  At 20 C they will germinate in 6 - 8 weeks, at 25 C it may take a couple of weeks less.

Growing on

Once they are large enough to handle, pot them singly in 7cm pots at first, stepping up in size as the plant grows.

Growing Pine (Pinus) and Spruce (Picea) From Seed

Place the seeds in a glass bowl of lukewarm water and soak for 24 to 48 hours.

Drain the seeds but do not let them dry out completely. Place moist seeds in a zip-loc plastic bag with some sterile substrate (spaghnum moss, peat or vermiculite) and place in the vegetable drawer of the refrigerator for 60 to 90 days. Do not allow the seeds to freeze. After the seeds have stratified for 60 to 90 days, remove from the refrigerator.

Alternatively place the seeds in a pot, as below, and place outside somewhere secure where they cannot be accessed by mice or birds and let the winter do the work. In this case sow them in September after the soaking process.

Prepare a potting mixture of 3 parts potting soil, 1 part peat moss, 1 part vermiculite and 1 part sharp sand. Do not use beach sand which may contain salt. Fill 4-inch pots with good drainage with the potting mixture. Place one seed in each pot. Cover the seed with one-quarter inch of potting mixture. Water well. Place in a full sun location, protected from the wind.  Sealing in a ziploc bag will help retain moisture

Keep the soil mixture in the pots uniformly moist. Consistent, even moisture is critical to seed germination. Do not allow the surface of the soil to dry out completely. As seeds germinate and develop, water daily. When seedlings are 8 to 12 inches tall, they are ready for repotting or transplanting to a permanent location.

Growing Fir (Abies) From Seed

Growing Fir (Abies) From Seed

Pretreatment

Seeds of the true fir species are relatively easy to germinate and grow. The dormancy within the seed is short and easily broken. This is achieved by a short period of cold stratification in the fridge.

You can do this by first soaking the seeds in water for 24 hours. Drain away all of the water and place the seeds in a zip-lock bag with a small amount of substrate such as spaghnum moss, peat or vermiculite. Place the seeds in the fridge, it is important that during this period that the seeds do not dry out or are waterlogged otherwise the pre-treatment will be ineffective. After 8 weeks under these conditions the seeds are ready to be sown. In general, the seeds will fail to germinate unless treated in this way, simply sowing untreated seeds in compost at room temperature will not break down the dormancy and germination will be disappointing.

Sowing

Fill your chosen container with a good quality general potting compost. Suitable containers could be plant pots, seed trays or plug trays or even improvised containers with drainage holes. Firm the compost gently and sow the seeds on the surface. If you are sowing in plug trays, sow 2 or 3 seeds per cell. Cover the seeds with a couple of millimeters of vermiculite or failing that a fine layer of sieved compost. Follow with a gentle watering and keep them at room temperature.

Germination will begin a few weeks from sowing. The seedlings are reasonably robust and trouble free and usually grow to a height of between 2 and 5 cm in the first growing season depending on the sowing date and cultural techniques. Densely sown seedlings are at risk from fungal diseases such as “damping off” which can cause rapid loss of many seedlings.

Growing on

Developing seedlings should be fine in full sun, keep them well watered and free of competing weeds. Growth will accelerate in the second and subsequent years and the developing young trees should be re-potted as necessary preferably during the dormant season. After perhaps 3 years they are ready to be planted in their permanent position

Growing Hoya From Seed

Growing Hoya From Seed

Hoya is a member of the large dogbane family and used to be part of the now defunct milkweed family.  The seeds are small and flat and have a silken parachute to aid with dispersal.  Once dispersal has occured the parachute serves no further purpose and will eventually rot away.  In the close confines of a pot, where several seeds may be sown in close proximity, the presence of the parachute is a route in for disease, so best to remove them before sowing.

Sowing

Sow in pots of sterile compost on the surface, just pressing them in.  Water well then seal the pot in a plastic bag to keep humidity levels high.  Germinate at 25 Deg C or so, cooler temps may delay or completely inhibit germination, which ideally should take around 2 - 8 weeks.
During this time watch out for any fungal infections, because once they take hold they will spoil all the seed.  I have taken to sprinkling fine sand around the seeds so as to give the seeds a change whilst suppressing any spores that may try to take hold.  Another method is, prior to sowing, soak the seeds in a dilute bleach solution at the rate of 5 ml to 500 ml of water for about 10 minutes to kill any spores.  Once the 10 minutes are up, rinse them in clean water to remove all traces of bleach.

Growing on

Once the seedlings emerge, change the air in the bag by opening for a few hours, then re-seal.  Once the true leaves develop the bag can come off and the seedling can be potted up once they have outgrown the seed pot.

Grow Tent - A New Experiment

Grow Tent - A New Experiment

Finally took the plunge and invested in a grow tent for seed testing.  Big enough to provide for 115 x 7 cm pots, it should allow me to test pretty much all of my smaller seeds.

So far it has all of my seeds that require very warm conditions, with the bottom heat and the ceramic heater providing air temps of a stable 26 Deg C and soil temperature a few degrees above that.

At this point, I have had Stapelias showing in 24 hours from sowing, Pachypodiums from 48 hours, Astrophytums in 72 hours and my own super hot chilli peppers germinating inside 4 days.

The kit so far includes

1. 120 x 60 x 150 cm Grow Tent
2. 2 x 50 cm square heat mats
3. Minature Fan Heater (400 watts) with thermostatic control
4. 600 LED full spectrum grow light
5. Inline vent fan (not currently being used as I need a close atmosphere)
6. Remote temperature and humidity sensor so I can check temps without leaving the house

As I get results from this, I will be able to modify any care sheets that I have for the more tropical species we stock.

Growing Melon and Cucumber Relatives

Growing Melon and Cucumber Relatives

All of these seeds require pretty much the same treatment when it comes to germination.  The seeds should be pressed in to the surface of the compost, edge on, and then covered to at least the depth of the seed.  Water well, then seal in a plastic bag or place under some other clear cover to keep the humidity and moisture in the soil.  Place somewhere light at that point, a warm windowsill or better still a heat mat or propagator.

Germination

Germination should then be conducted at temperatures between 20 and 25 Deg C, as these are all from warmer areas of the world and need this kickstart to get them to germinate.
Under these ideal conditions, germination should take 7 - 21 days.  Once the seedlings emerge, grow on in slightly cooler conditions, providing some shading from any scorching mid-day sun, as these will naturally germinate in grass or under shrubs which provide such shading.

Growing on

Continue to grow on, commencing a dilute feed regime when they are four weeks old increasing the amounts as the plants get larger.
Annuals may eventually go into grow bags, where they can be grown happily for the season, or into open ground or large pots if you prefer (the former only when the soil is reliably above 6 Deg C day and night and there is no chance of any frost.  Perennials should be grown in large pots unless you live somewhere entirely frost free year round as frost will kill off the top growth and if hard enough it will kill the perennial rootstock which allows the plant to overwinter

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.

Amorphophallus Corms

 Amorphophallus

Most years we have Amorphophallus bulbifer tubers in stock, usually during the period January to July (after that we have either sold out for the year or planted them ourselves to save any extras going to waste).

Every now and then we get other species such as konjac and nepalense in stock or as offshoots of our own plants - rare events so the availabilty is patchy.

To plant these corms and tubers, you will need a relatively wide pot, at least 4 times wider than the corm.  If potting several corms, allow sufficient space for the corm to double in size, in this way they can stay in the same pot for a couple of seasons.

To plant them, there is a 'right' way up and a 'wrong' way.  The right way is with the domed side uppermost.  If there is no obvious domed side, not to worry as planting the wrong way, the corm will still send a shoot up and its roots down and sideways.   Plant each corm to at least its own depth in compost.  Free draining compost is ideal, either soil or peat based.  If using peat based, add some perlite or vermiculite so that it is easily re-wet after the winter rest.

Warm, bright but out of direct sunlight until the leaves are full developed - so under the shade of shrubs or on the greenhouse floor.

The plant will tell you when it needs water (it will have a shoot above ground) and when to stop watering for the year (the shoot withers and yellows).  Feed well to plump up the corm and you will have a flowering sized specimen in a few years.  Flowering sized corms often 'shatter' after the flowering, producing many smaller bulbs that will grow to flowering size again in a few years.  A. bulbifer will produce a mass of corms in between the leaf axils of the large palm like leaves which can be used to grow new plants.