Wakehurst Place near Ardingly in West Sussex is a National Trust property with grounds run by Kew, with their main Royal Botanic Gardens being based 10 miles from central London. The main difference between the two sites is that Wakehurst Place is home to Kew’s Millenium Seed Bank, a building officially opened in 2000 by HRH Prince Charles, who called the centre and the project ”The Bank of England of the Botanical World”
I recently visited the Seed Bank visitor centre, as they had a special “Seed Swap” event taking place, where people could bring spare seed of any type and swap with others (not from the seed bank !) I was able to see inside the seed vault, something that isnt normally allowed and was able to attend some very interesting talks on the subject of seed saving and how to store seed to ensure it lasts, more of that in a bit.
The Millenium Seed Bank have been working with over 50 countries around the world to try and harvest, store and safeguard over 24,000 plant species, in fact they have already assured the future of nearly all the 1400 native plant species from the UK and by 2009 had reached their target of gathering 10% of the worlds plant species. The next target being to try and secure 25% by 2025.
The seeds are collected, catalogued and then subjected to a very careful drying process bringing the Relative Humidity (RH) of the seeds down to 15%, they are then stored in vials, put in to Kilner type jars and then stored in the underground vault at a steady -20 degrees centigrade.
You may be wondering what this has to do with Chillies? well if you are a Chilli grower you will be no stranger to saving seed from your crops whether from isolated crops or not, the principles are still the same, and according to the experts at the Seed Bank, 15% RH and -20 degrees are the optimum storage conditions for most seed and if you can achieve those conditions at home then you could prolong the life of your seeds for a lot longer than you might think.
In fact one of the experts clearly stated that if you can achieve these conditions at home, then you can quite easily ignore those “sow by year ending” dates.
Some seeds though are inherently short lived like Parsnips, but an example was given of some french bean seeds, usually given a couple of years to sow by the seed companies (and if you store them in a drawer in the shed that date wouldnt be far wrong) but if you can achieve the conditions above, through computer modelling and lots of techy stuff, they have calculated that those seeds could stay viable for in excess of 6000 years!!
Keeping a handle on the Relative Humidity of the seed is the key, it can be measured using a Hygrometer which you can buy from the internet from as little as £2 to many hundreds of £. This can measure the air around a seed usually in a range from 10% – 99%. To give your seed a half decent chance of keeping its viability, it needs a maximum of 50% RH, but 30% – 15% is optimum, the nearer to 15% the better. Longevity doubles for every 10% reduction in RH of the seeds you achieve!
Another interesting factor is the temperature. I have always heard about storing seed in the fridge or the freezer but have always felt a little scared to do it! but again according to the experts at the Seed Bank, for every 5 degree drop in temperature from ambient levels, longevity doubles yet again!
Now if you think this sort of thing is difficult and something only scientists in white coats can do then you are wrong, with the right equipment, you can achieve these results at home.
One way is to use this, a Mini Seed Bank
This has been created by Kew for the home grower. This is a collection of the equipment you might need to achieve the best results.
It contains the following items:
A large plastic box which becomes the main seed bank, a large bag of white silica gel, 6 large screw top clear plastic pots, 8 small screw top clear plastic small amount of yellow silica gel, small sachets of green silica gel, paper seed envelopes, labels, a large material bag, and a pencil. The coloured silica gels are actually the same, but are called “Indicators” as they contain methyl violet which turns the silica beads green when moisture is present and orange when they dry out.
So how does it work? Firstly you need to save your seed from your Chilli (or other plant) and you will find an article on how best to do it from Phil at Dartmoor Chilli Farm here.
Once you are ready, the bag of Silica gel is poured into the main plastic box followed by the orange Silica gel and mixed (it is important to point out that the gel is poisonous and hands should be washed after using it)
Next put your seeds in a pot and add a green Silica gel sachet to the pot, leaving the lid off each individual container.
Then the lid can be put back on the main box firmly, this creates an airtight drying environment. The box should be put somewhere unheated and out of direct sunlight. It should be opened every 3-4 days to check the colour of the indicating sachets. The seeds should be moved around in their pots to ensure even drying.
They should be dry when the sachets have turned orange, usually about 10-14 days depending on the type and quantity of seed being dried.
When the sachets turn orange, the screw top lid to each individual container can be put back on with the sachet still in place, or the seeds can be transferred to paper seed envelopes, labelled and then a number of envelopes can be put in one of the large plastic containers and kept in the main box. Once all seed for the season has been saved, the paper seed envelopes and their seed can either be kept in the smaller sealed pots in the main box with the bed of Silica or they can all be put in a Kilner Jar (not supplied) which will will fit in the main box.
This can then be stored in the fridge or freezer until seed is required.
The way this works is that the moisture is drawn from the seeds and the green sachets, and gets absorbed into the bed of white and orange silica gel. This then regulates the RH of the air in the box to a low level. You can buy a cheap Hygrometer and keep that in the box too to find out exactly what level it is at but its not essential.
Mini Seed Bank kindly supplied by Kew Wakehurst Place
I think it is a great product and something I will definitely be using to store my seed instead of the current non sealed container.
The Mini Seed Banks are available from Kew directly or from their online shop priced at £24.99 plus postage.
Obviously this method is not essential, it helps to regulate “ideal” conditions, but if you want unused Chilli seed to have a better chance of germination over a second, third or even fourth season then this product will certainly help.
So there you go, I currently have seeds drying in one and will see how it goes.
**Please note, if you choose to store your seeds in the freezer after reading this article, it is your decision!**