Saffron crocus

Saffron (Crocus sativus) is a very easy plant to grow.  I have been growing saffron for a number of years, and it flowers reliably for me each year.  While the spice is expensive, growing saffron is surprisingly simple and cost effective.  

Saffron grows from a corm (a corm is similar to a bulb) and is dormant over summer.  Saffron only flowers once per year, and each saffron flower only produces three threads.  Given the price of saffron you want each corm to produce as many flowers as possible.  

Saffron threads from my plants

Saffron flowers reliably for me each year.  The flowers are pretty, and the plant takes up little space. 

From what I read online, many people seem to get good flowering in the first year but have trouble getting saffron to flower reliably in following years.  I think this is because they are following bad advice, they treat saffron corms like flowering bulbs and have poor results.  

Saffron needs slightly different conditions than most bulbs to flower well.  Luckily these conditions are even easier to achieve than the conditions needed by many flowering bulbs. 

Saffron corms 

Firstly, some things are the same between saffron corms and ornamental flower bulbs.  

Larger saffron corms produce more flowers, and smaller ones don't flower at all.  This makes sense.  You can even work out flowering size by measuring the corms.  

Don't measure the width of the corms, they aren't very round and it is impossible to know where to measure.  It is more accurate if you measure the circumference.  The simplest way is to wrap a string around the, then measure the string.  All saffron corms that have a circumference of 7cm or more will flower.  It's that simple. 

For me a corm 7cm circumference (not width) usually produces 3 or 4 flowers, and larger corms produce more flowers.  Some smaller ones may flower, but most won't.  

Mine don't often put up all the flowers at once, each corm seems to take its time and puts up a few flowers over a few weeks.  While this makes growing commercially difficult to get pickers when needed, it is not an issue for the home gardener who can pick threads whenever they are ready.  

Saffron produces beautiful flowers

Fertilising during the growing season, and leaving the leaves to gather energy and die back naturally helps the corm to grow larger and produce more flowers in the following year.  Fertilising won't help this years flowers, it will help the corm grow strong and produce flowers next year.  

I find that top dressing with guinea pig manure results in larger corms, and more flowers the following year.  I've tried using compost, green manure, vermicompost, and poultry manure, all of which work well but nothing seems to work as well as guinea pig manure.  I have never used store bought fertiliser, so can't comment on its effectiveness. 

Saffron needs a cold winter to flower well, which we have here and saffron seems to like it.  I have no idea how they would go in climates with mild winters, I assume they would struggle.  Don't lift corms and store in the fridge like a tulip, when dormant saffron corms need heat.  

Some dormant saffron corms of various sizes

Saffron needs a hot dry summer when they are dormant, which we have here.  If we get a wet summer I dig some corms and put them in the garage somewhere dry.  Putting them in the garage somewhere hot and dry would kill most flower bulbs, but heat when dormant helps saffron to flower well.  If I lift them I tend to split them into batches and put them in mesh bags and hang them on a nail.  

Leaving the corms in the soil works well only if the soil is relatively dry, if it is too wet they will rot.  I grow some in pots, I can move the pot under cover when they are dormant so they will be dry over summer.  I want to stress, do not put dormant saffron corms in the fridge, saffron corms need heat when dormant.  

The thing that makes the most difference to saffron flowering, and the thing most people get wrong, is the depth they prefer to be planted.  

Saffron flower before fully open

The advice given for most flowering bulbs are planted twice as deep as the bulb is tall.  This is far too shallow for saffron corms.  If you want saffron to flower well, they must be planted deeper.  Saffron prefers to be planted much deeper than you think.  Even though the corms are relatively small (a corm with a 7cm circumference is rather little), plant them 15-20cm deep.  Larger corms can even be planted a little deeper than that.  If you plant them shallow they will not flower well.  

Healthy saffron corms divide each year.  One corm can produce anywhere between 0 to 15 new corms each year.  I prefer my corms to produce fewer, but larger, corms.  Large corms flower, and larger corms produce the most flowers. 

Planting shallow will usually mean your corms will divide into many tiny corms, none of which will be large enough to flower.  You don't want this.  Planting deeper means you get less division, but more larger flowering size corms.  

It feels like planting a small corm under 20cm of soil is too deep, and it feels like it will not have enough energy to reach the sunlight, but they will be fine.  If you don't plant this deep they will not flower well next year.  Plant saffron corms deep. 

Saffron growing in a pot - lower plant has several flowers 

I grow saffron in large pots as well as in garden beds.  Both work well as long as I can plant the corms deep enough and they have good drainage.  Saffron corms can rot if they are too wet.  

The past few years I largely forgot about my saffron and left it to do its thing.  During this time it multiplied, and the corms got smaller and smaller.  I still got a few flowers, but overcrowding lead to less and less flowers.  

This year I divided my corms, planted some in pots, some in the garden, and some in mesh bags that I still need to plant.  I planted them deep, and fertilised with guinea pig manure.  While I won't get a lot of flowers this year, the small corms will grow larger and many should be large enough to flower next year.  

Saffron starting to flower

Saffron is a sterile triploid that does not produce seed.  

If you want to grow saffron, you must get corms.  You can not buy saffron seeds.  Saffron seeds don't exist. 

You will see a few people online selling what they claim is saffron seed.  These people are thieves, they do not have saffron seeds and they are trying to steal your money.  They will send you seed from whatever they have on hand, it won't even be crocus seed.  By the time it grows and you realise it is not saffron you have already left positive reviews and it will be too late for you to do anything to get your money back.    

Many of these thieves have pictures of other species of crocus in their listing.  This is a giveaway that they are not honest.  Saffron does not grow from seed, do not buy anything from anyone claiming to sell saffron seed.  

Dutch crocus 'pickwick' is not saffron

While saffron is given its own species name (Crocus sativus), this is slightly misleading as it is either a mutation of Crocus cartwrightianus or possibly an interspecific hybrid involving C cartwrightianus.  

Saffron is pollen sterile, but under some circumstances it is possible (albeit rather rare) for it to develop hybrid seed.  There are a few papers where pollen from C cartwrightianus produced viable seed in saffron.  You will never see seed of this cross for sale because it is very difficult to produce, and most of the seed is not viable.  I am unaware if the ploidy level of these hybrids has been tested, and I assume the resultant plants have never achieved any commercial success as they are not particularly great.  

I would love to get my hands on C cartwrightianus and try to cross them with saffron.  There used to be one place in Australia that sold this species, but they went out of business before I go a chance to buy one.  If you know anyone with this species in their collection I would very much like the chance to grow some and try to cross it with saffron.

If you are thinking of growing saffron you should give it a try.  Like most things, growing your own saffron works out to be more cost effective than buying it from the shops.   

One reputable company in Beechworth sells small packets of saffron for $3.  These packets contain 6-9 threads, which is meant to be enough saffron for an average dish for 4 people.  

My corms tends to produce 3 or 4 flowers each, which is 9-12 threads.  This means that one corm usually pays for itself in its first year, plus you get to enjoy the beautiful flowers.  

Each year the corms tend to divide and multiply, meaning you get more saffron each year.  

I used to sell saffron corms, but I don't have any for sale this summer.  I don't have many flowering size corms this year, and I don't like selling smaller corms that are unlikely to flower.  As mentioned further up in this post I divided my corms, and if all goes well I should have a lot of larger flowering size corms next year.  

If all goes well, I hope to sell saffron corms in future years.  If this happens they will be listed on my for sale page.  If you know of a source of Crocus cartwrightianus in Australia, or you have some that you may be willing to part with, my contact details are listed on my for sale page.