Tomatoes: Potato Leaf vs Regular Leaf

People often talk about regular leaf tomatoes or potato leaf tomatoes, I get a few questions about this so I figured I would write a post explaining what is meant by these terms.  I have also seen one place sell a variety of tomato that they call "potato leaf tomato" and I find this confusing as there are many varieties of potato leaf tomatoes, I am growing 4 of them this year myself.

Have a look at these two leaves, they are both leaves from tomato plants.  Please ignore the yellowing, that has nothing to do with leaf type, that leaf is a bit older.

Potato Leaf compared with Regular Leaf

It is not too difficult to tell them apart, the leaf on the left looks like the leaf on a potato plant, the leaf on the right looks like the leaf on most varieties of tomato.

Regular Leaf (RL) tomato

Regular Leaf (often abbreviated RL)

This is the typical leaf type that most people are familiar with, most varieties of tomato are regular leaf.  The leaf edges are serrated quite a bit.  There are a lot of variations on this basic theme in terms of the width/length of leaf depending on the specific variety, climate and growing methods.  There are a few other variations such as angora, variegated etc but they are not easy to come across in Australia so I wont talk about them.  Some leaves are very narrow and are sometimes called 'dissected', others are wispy or droopy or look like the foliage of a carrot.  These are easily recognised from a distance even by my 5 year old as the leaves of a tomato plant.  All of this is referred to as Regular Leaf (RL).

Potato Leaf (PL) tomato

Potato Leaf (often abbreviated PL)

These leaves usually have very few interruptions of the leaf edge.  They are fat and large leaves. Newly germinated seedlings sometimes don't show their PL nature until they are a few inches tall, others show it as soon as they grow their true leaves.  PL leaves often have a thicker cuticle than RL leaves or a higher density of trichomes (which are tiny little hairs on the leaf).  Some claim that makes them more tolerant of foliage diseases but I have seen no proof of this.   Leaf shape can be different on a single plant with some showing more or less smooth edges, all of this is normal for PL.  Scientists have divided the PL leaf forms into various different classes but few of them are available in Australia and it makes no real difference so I wont write anything about them.

What is the deal with growing Potato Leaf tomatoes?

Some people claim that potato leaf tomatoes taste better, unfortunately that is a half truth.  Almost all Potato Leaf tomatoes are heirlooms and generally heirloom tomatoes taste great.  Some tomato varieties have a Potato Leaf version as well as a Regular Leaf version, I can not taste any difference.

People often claim that Regular Leaf tomatoes do not cross pollinate while Potato Leaf tomatoes will cross readily.  Unfortunately this is not at all true.  Most modern bred varieties of tomato will not cross pollinate easily (literatures states around 5% crossing without intervention when being grown side by side), almost all heirloom tomatoes do cross pollinate, some far more than others.  As most Potato Leaf tomatoes are heirlooms people have got themselves confused here.  The tomato I grow that crosses most readily is Reisetomate, it is a regular leaf plant.  It cross pollinates so much that I even grow it in a separate garden to all my other tomatoes.  Try not to be fooled, Potato Leaf does not necessarily mean heirloom, just as heirloom does not necessarily mean Potato Leaf.

Potato Leaf is considered to be a recessive trait.  When breeding new varieties if Potato Leaf is crossed with Regular Leaf then all the seedlings will be Regular Leaf.  This makes it useful to see early on  if the cross has worked or if the flower self pollinated and the plant is worth growing on or not.  If growing different varieties of tomato then Potato Leaf can also indicate early on if that particular seed has remained pure.  If a potato leaf variety grows regular leaf the chances are high that it has crossed.  Some potato leaf varieties do occasionally throw a regular leaf plant even when they have not crossed, so things do get a little confusing here as there is a little more to it than a simple dominant/recessive trait.

"Julia Child" a great potato Leaf tomato variety

I have heard theories about potato leaf being more resistant to insects and regular leaf being more resistant to insects and visa versa, but I have found nothing conclusive that back up this.  Potato leaf would possibly restrict airflow more than regular leaf, so it is possible that potato leaf would face more mold problems in damp environments but again I have no proof that confirms or denies this.  I live in an area of low humidity, so it doesn't matter to me in the slightest.

I have also heard anecdotal evidence that potato leaf varieties are more 'hungry' than regular leaf as they require more resources in order to build more leaf, again I am yet to find any research that either backs or refutes this claim.  It kind of makes sense to me, but some of the largest tomato plants I have ever seen have been regular leaf, I assume they used a lot of resources to grow that large.  I have one regular leaf tomato that grows a large shrub to about 8 feet in every direction, it is surely using a lot of resources to build all of that stem.

Some people think the Potato Leaf plants look nicer, I certainly think they look more ornamental and would not look out of place in a flower garden.  To be honest, I wish that I had more potato leaf tomato varieties as I simply like the look of them.

At the end of the day though the leaf shape makes no real difference to me and I doubt it makes any real difference to taste, growth rates or anything other than aesthetics, so I base my planting decisions on the taste of the fruit and performance of the plant.

I do sell seeds of some heirloom tomatoes as well as perennial vegetables on my for sale page, you should have a look if you are interested.

Perennial Tomatoes

Everyone loves tomatoes, they are often grown as annuals and may people complain that they wish there were perennial tomatoes.  Well, there are perennial tomatoes.  I have seen seeds of perennial tomatoes for sale on ebay fetching serious money and I ask myself why.  Perhaps it is because people do not know about how to grow perennial tomatoes.  They are far more common than you think.

Indeterminate tomatoes can be grown as perennial tomatoes

Different types of tomato

There are many thousand different types of tomato, I am not exaggerating here, probably over twenty thousand recognised varieties world wide with a lot more being developed (by home growers such as myself as well as Government breeding programs) each year and a lot becoming extinct each year.  In the supermarkets we probably have access to half a dozen or so, by growing heirlooms we have easy access to several hundred varieties of all kinds of shapes/sizes/colours.  By growing heirlooms it is simple to save seed of the best varieties each year.  Of the many varieties of tomato that we have the easiest access to they can be roughly divided into two groups: determinate and indeterminate.

Roprecco Paste, a good determinate variety

Determinate tomatoes fruit pretty much all at once, then they tend to die, they are most easily grown as annuals.  They produce flowers at their terminal bud, after they flower that branch can not produce more leaves and stems.  These are great if you want all of your crop to harvest once, they are great for large scale farmers who only want to harvest once, as well as people who are into home preserving.  If you are planning on making paste or sauce then you probably want a determinate variety, there are several incredibly old and delicious heirloom varieties that are determinate.  I don't grow many of these, but I do grow a few, they serve their purpose well.  Some places claim determinate tomatoes are short and do not require staking, this is not always the case, please ignore anyone who makes such claims and stop buying seeds from them.

Speckled Roman, a good indeterminate variety

Indeterminate tomatoes can fruit over a long period, they keep growing as long as you protect the plant, they can be grown as perennial tomatoes if grown without frost.  They grow flowers from a side bud, not the terminal bud.  These are great if you want a few tomatoes each day or every few days, for many weeks/months on end.  Most varieties of tomato grown at home tend to be indeterminate, most heirlooms tend to be indeterminate (but there are some determinate ones too).  Some of these plants can grow massive while others can be rather compact.  Even though indeterminate tomatoes are perennial tomatoes they still tend to be grown as annuals.  Almost all indeterminate tomatoes are perennial tomatoes, no need to spend ridiculous amounts of money on "perennial tomato" seeds now.  Some places claim that indeterminate tomatoes are tall and require staking, this is not always the case, please ignore anyone who makes such claims and stop buying seeds from them.

Perennial Tomatoes

Many varieties of indeterminate tomato are a short lived perennial if grown in a warm climate, which is great if you happen to live in a warm climate.  Sometimes they can survive for several years but the productivity often drops off after the first year or two. 

I live in a frosty climate and have often wanted to grow the same tomato year after year, not just save seed, but keep the same plant going.  Even if you live in a frosty climate it is possible to over winter plants.  They probably won't produce a lot of fruit over winter (unless they are parthenocarpic), they will continue to flower but often the nights are too cool for fruit set, as soon as the weather is warm enough they will be ready and will ripen some early fruit for you.  This is a great way to get your plants to set fruit a few weeks to a few months earlier than from seed.

Overwintered Reisetomate set fruit 2 months earlier than the seed grown Reisetomate

Each year I overwinter some tomato plants.  Sometimes I do it because I am running low on seed, sometimes I do it because the plant was amazing and I want another season out of it, sometimes I do it because I am developing a new variety and would like to back cross its progeny with it to lock in a certain desirable trait.  Plants that are overwintered tend to crop a lot earlier and be more resilient than seedlings of the same variety.  Sometimes I overwinter a plant to help get an early crop and beat the extreme weather that we often get.

Yellow Pear tomatoes are simple to grow as perennials

How to overwinter an indeterminate tomato

This is one of those things that depends on a lot of different factors, mostly it depends on what you want to do and in which climate you are growing tomatoes.  You may wish to put up a shade cloth structure or something to protect a plant growing in the soil.  You may grow a plant in a pot that can be moved to somewhere safe.  You may live somewhere that the plants can be left as they are or just mulched carefully.  I take cuttings and overwinter these.

I take a cutting late in the season from the plant that I want to overwinter.  I use indeterminate varieties, while it is possible to use a determinate variety it is far more difficult as timing has to be just right and sometimes cuttings have to be taken throughout winter to prevent flowering.  Remember, if a determinate tomato flowers it will not grow any more or be able to produce new leaves or new sets of flowers.

The cutting will be genetically identical to the original plant, it is essentially the same plant.  I remove any flowers, remove the lower leaf or few leaves as they do not cope under water, then put the cutting into a glass of water.  The part I cut needs to be under water, the leaves need to be above the water, very simple.  You could plant the cutting directly into soil at this point instead of using water but I like to see the roots first so I use a glass of water.

Tomato cutting, ready to plant into soil

Normally in 3 days small roots appear, it may take a lot longer in cooler weather, it may be as fast as 8 hours in the right conditions.  The roots grow fast once they have started so I try to plant it into a pot of soil quickly.  Water roots are different from soil roots, so it is best to plant it after the roots are only short rather than wait a few extra days until they are long (like the picture below).  I then put this potted cutting somewhere safe over winter.

During this time it will grow and it should flower, mostly the flowers abort as the night temperatures are too low.  I grow them outside under the verandah against the mud brick where they get sun and warmth but no frost, if you live somewhere colder you could grow them inside near a window for light.  They need sunlight or they will become sick and attacked by insects.

This is the same cutting on the left, the second cutting was put in the water when the first picture was taken

After the frost has passed I often have a strong 3 foot tall flowering tomato plant ready to be planted out in the garden (or left in the pot and moved into the sun).  Quite often seed grown plants will only be 10cm tall at this time so the overwintered plant gets a significant head start.

This process of taking cuttings to overwinter can be continued indefinitely, each time you take a cutting you are restarting the clock and the plant will not die of old age.  If you have found a good F1 hybrid that you like and can not save seed from you do not need to buy new plants each year as you can simply take a cutting and overwinter the same plant.  You no longer need to waste money on 'perennial tomato' seeds, just look for a good indeterminate variety as they are perennial.

Far too easy, you now have perennial tomato plants even if you live in a frosty climate.  I sell some heirloom tomato seeds on my for sale page.  Many of these are indeterminate and can easily be over wintered, if you are interested please have a look.

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Edit to add:
I have grown tomatoes and overwintered them too many times to remember.  I am now wondering if in cold climates in small backyards if it is worth while growing them as perennials. 

Tomatoes grow so easily from seed and the space that they need over winter may be better used by something else that can not be grown from seed.  Overwintered tomatoes do fruit about 2 months earlier than seed grown, which is great, but space is so limiting now we live in town. 

I also have a few super early determinate varieties such as 'igloo' that will grow, fruit, and die before most other varieties start to ripen.  This means I can grow all from seed, have early tomatoes from 'igloo' and late tomatoes from other varieties and not have to protect anything over winter.

Immali Corn - Coloured Sweet Corn in Australia

I started messing around with corn breeding a few years ago. Corn genetics is messy, the more I learn the more I find that I don't know.  Genetics was so much easier when we knew nothing!

Many varieties of corn suffer from varying amounts of inbreeding depression, to save seed it is best to grow at least 200 plants and save seed from the best 50 to 100.  Some varieties of landrace corn have little to no inbreeding depression, but the down side is that they can be rather variable.  Using landraces as breeding stock means that genetic bottlenecks are not as tight and small populations can be slightly more forgiving.

Corn will happily cross pollinate with other types of corn that are within a few hundred metres up to a few kilometers of each other.  This makes saving corn seed difficult unless you live on acreage and have no one growing corn near you.

As I currently live on acreage and have no one growing corn close to me I save seed from a few different types of corn.  If I get the timing right, and am vigilant with selecting seed and rogueing out off types I could probably grow half a dozen types of corn each year without too much trouble.

I grow some interesting coloured corn, most of which is popcorn or dry corn as there are very few coloured sweet corn varieties available in Australia.  I once looked online at the amazing coloured sweet corn that is available overseas and asked myself: "self, why doesn't someone in Australia breed a decent coloured sweet corn?"  I looked around for someone who was developing a decent coloured sweetcorn in Australia, I could not find them.  I did find some people who are maintaining a few coloured sweet corns and a few who are developing the most wonderful yellow or white sweet corn, but none of this is what I was after.

So I decided to try to breed one myself.

Immali Corn 2015

I have some access to different coloured field corn and some different varieties of sweet corn that the average grower would not have seen.  I researched the varieties that I have access to in order to determine the best parental stock for my new variety of corn.  I got a landrace coloured sweetcorn, which tasted ok and has a lot of genetic variation.  This was one of the parents of Immali corn.  Every generation since then has been remarkably better tasting.

Some "Immali corn" seedlings

I planted some of the coloured seeds and saved quite a lot.  The results were good, but being so early it is clearly not stable and had a way to go.  A little back crossing would help to lock in the desired colours and also maintain a high level of genetic variation.

The early cobs lacked much colour, they tasted better than store bought corn but not as great as I had hoped.  Adding colour is not all that difficult, stabilising that colour is a bit more difficult, but I can do it.

Early Immali corn (ignore the yellow) - needs more colour

Tastes great, looks ok I guess, still a way to go

The later cobs look far better and taste far better too.  It is too bad I only get one crop of corn per year so progress is painfully slow.

Look how far it has come

Some fine looking "Immali corn" cobs

Still not there but look how far it had come

They still have a way to go, it is not yet stable and I do not want to distribute this seed until it is a bit more stable.  The colour will always vary a bit, but that is kind of the point.

The taste is a bit up and down right now, some cobs taste good while others taste simply amazing, all of them taste at least as good as store bought sweet corn.  This is mainly due to timing, if picked just right they blow me away, if picked too early or late they are not as good.  I would like to work out how to fix this, the genetics behind this are a bit beyond me at the moment as I do not have access to a good corn genetics book.  By only saving seed from the best tasting plants all of the Immali Corn should taste amazing by the time the colours are locked in properly.

I worked hard to get here, we ate this cob and the colours remained unchanged through cooking

Once the strain starts to look more consistently like the cob above and is a bit more stable I hope to distribute seeds.  It may never be truly stable, it may be best if it always stays a landrace variety at least to some extent.  I hope that some dedicated seed saver somewhere will see the merits of Immali Corn and continue to grow it after I am gone.  Perhaps I should tell you what i hope to achieve in this variety.

So if I can get more of the cobs to look like the one above, and get the taste to be a bit more consistantly amazing, what else have I tried to include in this variety?

I wanted a reasonably small plant that was productive.  I figure people have less land these days so need small plants that are highly productive.  While 12 foot tall monster plants such as the Giant Inca White corn is spectacular to look at, it is not practical for Suburban Joe to grow in the corner of his yard.  The Immali Corn only grows about 5 foot tall.  It is not a dwarf plant, but it is not a giant either, I think it is a nice manageable compact size.

Immali Corn, reasonably short plants

I also wanted to create a variety that would be productive.  No point having a variety of corn that only produces 1 or 2 cobs per plant.  So far the Immali corn has produced an average of 4 cobs per plant.  I always plant corn too close and the weather is not always kind to corn, given better conditions and more space I think it could average a few more per plant.  Each stem produces 2 good sized cobs on average (some only 1, others 4), but then this variety is very prone to tillering (growing several stems).  This is probably a bad thing if you plan to harvest using a combine, but it is a great thing for home gardeners who harvest by hand.  It essentially means you get several times the corn from the same amount of space.  I am deliberately selecting for plants that produce more tillering as it is this trait that has helped raise the average number of cobs per plant.

Sideways corn picture, note the 2 cobs forming up high and 1 more lower down

 As well as a great tasting corn that is productive and takes up little space, I wanted something that was good to look at.  The cobs needed good colour, which was the primary reason behind this project.  One of the bonuses to using a coloured landrace as one of the initial stock was that the tassels sometimes are purple, it makes the plant look a bit more ornamental.

Immali Corn tassels and cobs

Immali Corn silk

Some of the cobs also display coloured silk.  I do not know if I will be able to keep this trait in this variety, but I will if I can.  It is one of the least important things I would like in the variety, but it does add something special to it.


Where can you get Immali Corn seeds?

This variety is reasonably stable now.  The last two times I have grown it I have only seen one plant that was taller than normal and the cobs all look and taste the same.  Seeds are now available through my For Sale page.

I think that you should breed some type of vegetable that you like.  Perhaps don't start with corn unless you are already experienced in breeding and saving seeds, perhaps start with a tomato or some beans or something simpler like that.  You don't need any fancy equipment, I certainly don't use anything special.  You don't need formal training in Botany or Horticulture or Genetics like I have, but you can still produce something amazing that can be treasured and passed on to others.