One thing I learned eons ago is how different plant types rot at different rates. I won’t mix other bloom types with roses as the roses regularly last longer than anything else, IF they are not combined. Leaving Baby’s Breath or any other type of greenery or flowers in a vase of roses will result in “slime” forming in the water faster, even if you change the water in the vase daily. I’ll remove any foliage that may be submerged in the water; re cut the stems under water in a bowl to remove the trapped air bubble in their capillaries, then carefully remove the stem from the bowl of water to maintain the water droplet on its bottom to prevent permitting air to enter them so the siphon of the capillary action from the stem bottom to the foliage “pores” is maintained; then repeat for each stem in the vase. By keeping the vase only roses, recutting the stems under water to maintain the siphon and repeating it each time you do a water change into a washed vase full of clean water, you can dramatically increase the vase life of any rose, though the more fragrant types do last shorter than un scented types due to the oils and alcohols in the petals oxidizing and aging the petals faster. Warmer water in both the bowl for recutting and the vase will open the flowers faster than cooler or cold water and making sure you don’t place the vase where it will receive sunlight through a window or be in any direct paths of breezes from doors, windows, fans or air conditioning will also help increase their vase lives. You may or may not choose to use “floral life preservatives” as you wish. I generally don’t as I don’t cut blooms for inside my own house. I’d rather enjoy them in the yard, mostly using them to pollinate and create new seedlings. I don’t use them in vases I give away as I’ve never had any recipient ever put the kind of care and attention into maintaining a vase of roses I’ve given them as I did to create it, so I give it and if it lasts for them, great. If not, that’s on them.
So:
Yes, bacteria does shorten the life spans as it clogs the capillaries, preventing the uptake of water to maintain the stem and flower life. Use clean everything.
Yes, cutting the stems UNDER WATER in a bowl large enough to allow you to accomplish the task conveniently then removing the stem while retaining the water droplet at its bottom will maintain the siphon required to lengthen the flower life. Repeat this stem each time a water change is required or if the water runs out of the vase. Do it for any florist flowers delivered to you also for longer vase life.
Yes, higher water level is generally better than lower as it provides you more time before having to add more water to the vase, presuming nothing has contaminated the water in the vase in the mean time. Make sure there are no leaves IN the water as they will rot faster submerged.
Hotter air, more moving air, more direct sun will all reduce the vase life of any flower. Why do you think professional cut flowers are kept in refrigerators? The cooler the conditions the slower anything ages whether it’s meat, dairy or produce, which a vase of roses pretty much is. Moving air evaporates moisture from a vase of roses or a rose bush outside just as it evaporates sweat from your skin. You want still, cool air away from any a/c or heating vents or any windows where hot sun or hot breezes enter.
Yes, foliage and/or any “filler” in the bouquet will cause the roses to deteriorate faster as they rot, feeding bacteria and generating “slime” in the water faster than a woody rose stem does. If you must have all the other filler stuff in it so it’s more impressive for an event or gift giving, that’s fine, but if you receive one like that and you want the roses to last longer, pull them out, clean their stems under running water to remove any slime which may have started forming, recut them under water and place in a clean vase of clean water.
I don’t know if you’ve ever noticed, but rose catalogs used to mention “heavy petal substance” which was code for exhibitors that this one was good for exhibiting in rose shows. That also pretty much meant it had little to no scent. A commercial cut flower, like a good exhibition variety, requires stiff, durable petals which can withstand a lot of handling and shipping and maintain their attractive appearance. That “heavy petal substance” is a very waxy cuticle, or “skin” of the petal. That waxiness seals the petioles, the pores of the petals where any oils and alcohols which create scent would be. For those substances to create scent, they have to oxidize, react with oxygen in the air which literally generates heat and that heat helps to age the petal faster. Flowers with thin, more fragile petals, age faster due to their lack of the waxy cuticle. More heavily scented blooms generally lack the waxy cuticle and age faster. The cut flower stars generally have little to no scent and have petals you can molest quite a bit and still have them appear fresh and beautiful.
So, if you want a vase of roses to last a longer time, choose those with little to no scent. See if they have any records of winning at rose exhibitions. If they do, they will likely be longer lived cut flowers due to their “heavy petal substance”. If you want a vase of more highly scented types, go for it, but don’t expect AS long a vase life from them as you might receive from unscented types because it’s what creates the scents that ages the flowers faster, all other variables being equal.
Here is an article I wrote 20 some years ago about fragrance, discussing much about this subject, for which the ARS presented me an ARS Award of Merit. Fragrance: Much Ado About Nothing?
