Hybrids vs Heirloom Plants

When it comes to gardening there are two types of plants - hybrids and heirloom.  In order to understand the difference, you need to know a bit of basic genetics.  An heirloom plant is one that has not been modified other than by nature.  It breeds true  meaning if you collect seeds from the plant, the resulting plants from the seeds will be the same as the parent plant (P).  An hybrid is the crossing of two parent plants with different characteristics to result in a unique plant.  Now, let say we cross a plant with white (rr) flowers and a plant with red (RR) flowers.  I'm using r as the recessive allele and R as the dominant allele.  The rr and RR are the alleles for the flower colour so in this case the only way to get white flowers is to have two alleles that are recessive while the only way to get red is to have two dominant alleles.  Two of the same alleles is called homozygous.  A hybrid occurs when you cross two homozygous plants to form a heterozygous plant for that particular trait.  So in this case the cross is RR x rr.  The resulting pink flower plant (F₁) is the hybrid that in terms of alleles is Rr and it does not have the same flower colour as the parents (white, red).  What happens if we take that hybrid and cross it with the same hybrid for the next generation (F₂)?  Consider a cross between a pink flowered plant (Rr) and a pink flowered plant (Rr).  What we end up with is a 1:2:1 ratio of 1 RR (red):2 Rr (pink):1 rr (white).  In other words seeds collected from the hybrid do not breed true so you may get the one you want (pink) but there is also a chance of getting one you don't want (white or red).

To complicate matters further, plant reproduction can be sexual (seeds) or asexual (cuttings).  Even if you start with a hybrid, if you propagate via asexual methods, the resulting plant will be the same as the parental plant.  However, as we see above if a hybrid is propagated sexually the resulting plant may or may not be the same as the parental plant.  As a home gardener, what this means is seed collection should be done from heirloom plants not hybrids.   These are the seeds you want to keep to grow the same variety the following year.  Some hybrid plants are propagation protected meaning you can collect seeds but you cannot legally propagate via cuttings.  If you want to take cuttings from tomatoes to grow indoors, you should not take them from a propagation protected hybrid tomato plant.  There is nothing wrong with collecting seeds from hybrids but be aware some seed developers have introduced a gene into their hybrids that essential render the plant sterile meaning any seed produced will not germinate.  It would be a shame to collect seeds from hybrids anticipating the same variety the following year only to find you end up with something else (not always a bad thing) or worse yet the seeds don't germinate.  In addition to this, some seed developers have also introduced a marker gene into the plant's genome so they can identify plants illegally propagated.  This is not a huge concern for home gardeners unless you are selling or trading plants that are propagation protected.

I use a combination of hybrids and heirloom plants in my gardens.  I collect seeds from both but tend to focus on seed collection of heirlooms first to replenish my gardens for the following year.  I am careful to label as to whether the seeds were from an heirloom plant or hybrid plant but the reality is plant tags get lost over the growing season so sometimes a clipping gets through that shouldn't.  I'm not selling plants though.  When it comes to hybrids, I try to use hybrids that are not propagation protected especially for tomatoes that I like to grow indoors during the winter months.  Heirloom seeds are the ones you want to collect and protect!

Happy Gardening!

Garden Gnome
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