Culture, Tips, & Articles

How to Improve Ones' Chances on Making a Cross To Get That Successful and Desired Seed Pod.

The southwest has its own particular problems when it comes to fertilizing an iris.  While many parts of the country have to deal with tons of rain, we have to deal with intense heat, dry, dry weather, and a LOT of sun during our spring months!

First the basics: Select 2 freshly opened irises of your choice. Next: Locate the anther with pollen which is located just under the style arms, then pluck it from the flower using tweezers( it is more likely to find pollen when the weather is warm and dry).  Now take it to the disired iris and brush the pollen against the underside of all three stigmas (small lip-like structure on the lower surface of each stigmatic lip which is attached to the underside of the style arms). Don't forget to label your cross and record the cross somewhere on paper!!  You are going to want to know who the parents were when you introduce your iris!!  The 'Pod parent' is always listed first on the recorded cross, and the 'Pollen parent' is listed second. The record of your cross will look something like this: Mesmerizer x Honky Tonk Blues. If the cross "takes" /or is successful then the Pod parent will grow a small watermelon-look-like seed pod. This seed pod will hold anywhere from 1 to 120 seeds. The average seed pod has about 50 seeds, give or take. It usually takes about 8 weeks for the pod to mature. When the pods resemble a light brown walnut shell and the top of the pod begins to crack, it is time to collect the seeds.

Now this information isn’t only for southwest iris hybridizers; there are many pointers given in this article that will benefit all who make crosses.  So…… can we improve our chances to get that much desired cross to “take” and develop into a full grown seed pod?  Well………here are a few things I’ve learned and maybe this information can help you too.

One of the most important factors I’ve found is that the ground should be watered the night before or early that morning (a couple hours before pollinating takes place).  A moist ground seems to cause the iris blossom to become more receptive………possibly because it may help the plant to hold up better in warm breezes or withstand quickly climbing temperatures.  I’m not certain why - - but I’ve discovered (even with irises planted in pots) that if they are watered the night before (or early that morning), having moist soil when fertilization is taking place increases the chances of that cross significantly.

Another factor I’ve found to be true is how high the temperature of the day will reach to.  If the temperature of the day reaches over 82-83 degrees while the iris sits in full sun then it won’t matter how much you do, or how careful you are to make that cross - - it just won’t take! The plant will choose to combat the stress factor of the heat and sun rather than produce a pod. However I’ve also found that if the irises are given sufficient shade in the afternoon then they will tolerate temperatures up to 86-88 degrees before choosing to give up the fertilization of that cross.

A third factor I’ve found is that in many cases if there are aphids on the blossom or hiding in the plants’ sword-like leaves then that cross will not take either.  Make SURE before you make that special cross that no aphids are present.  They will literally suck the life out of your fertilized iris embryo – sometimes before or sometimes after it “takes”.

Other factors I’ve found to help increase your chances to get that much desired cross to “take” is A.) Look for that shiny, sticky area just inside the lip area of the style arm. If it’s not shiny and sticky don’t waste your pollen; wait until it IS shiny and sticky. B.) If you want that cross to take then pollinate it heavily. C.) I’ve found that fresh fluffy pollen will pollinate better than old pollen.  But…….if you only have old pollen then use it.  Many times I’ve found it will work too!  D.) After you place the pollen inside the lip then carefully, gently press that area you’ve just pollinated using your thumb on one side and your finger (or two fingers if you have small fingers) on the other. It helps to seal the pollen onto that sticky substance.

Another thing I’ve noticed is that light breezes seem to be OK on a newly fertilized iris, but not so much so if it’s terribly windy. 

Question: Now – Let’s say you have potentially awful (way hot, cold, or rainy, etc) weather a lot of the spring, but you’d like to have a nice seed pod or two develop on this one certain favorite iris of yours.  What can you do to help improve the chances?

Answer: In the fall plant a couple of rhizomes of your desired favorite iris in a 5 gallon or larger container/ or pot. Leave it outdoors as you would your other irises, only slightly more protected, possibly under a porch or next to the house.  When spring arrives and the stalks produce buds that are beginning to open (and if the weather is hostile) then bring the pot indoors. Once indoors use a spray-mist bottle to create a more humid environment for the potted iris.  Then proceed with the fertilization process.  If the weather continues to be unfriendly then leave the plant indoors misting it on a regular basis.  You may also take it outdoors again as the weather turns nice, and then bring it back in when the weather becomes hostile again. I’ll be the first to admit the chances are not THAT good, but they are not bad either!!!  I’ve had several fertilizations “take” indoors using this method. But note:  Once you can see a pod forming, don’t think it’s free and clear to put it back outdoors.  Oh no……wait until the pod is of good size before you put it outdoors in extremely hostile conditions (way too hot, too cold, too rainy, too windy, etc.). Or wait until the weather is nice. If the pod is young/ too immature and placed outdoors in hostile weather, then once again the plant will sacrifice its’ pod due to the stress factor it has to overcome.  The iris plant will choose to protect the health and energy in the rhizome over caring for its’ pod.  (A tomato plant does just the opposite - - it’ll hold onto its’ newly formed tomato because its future lies in those seeds. A tomato plant has no rhizome to care for.)