Question on fertilizers

I haven't fertilized yet. Due to health, travel, weather (lots of rain) and weird temp fluctuations, I'm just now out in the beds. it's only 3-4 weeks or so before bloom begins.

should I try for the 10-10-10 recommended 10 weeks before bloom?
or should I try for the foliar feeding of Peters recommended 4 weeks before bloom?
or a combination?
or maybe half strength of both?

I have created a lot of leaf spot problems by spraying liquid fertilizer on my irises. If you
are having a lot of rain, more moisture is the last thing you would want. Standard granular
fertilizer takes about a month to break down into useable nutrients for plants except for the
nitrogen of which irises need very little. Quick release fertilizers usually burn the roots if
applied too closely to the stems/rhizomes etc. (So said some of the old time farmers--I
can't testify one way or the other).

A light application now will surely help the plants store food before they go dormant. I do
believe a little fertilizer goes a long way with irises.

We used 9-23-30 this year, picked it up from the local co-op.

Wish I could pick up that TNTigger but for 3 acres can not so use triple 10 or triple 15 if can not get a much lower nitigren

D

Because of rain and the fact that you sink right now and growth a little behind schedule will fertilize next week hopefully...

D

I use a 5-50-10 in granuals and spread it after the preen or other weed prevented in watered or rained in at the same time I add my lime. Then spray with fungicide

PS Aril and Arilbreds do not get this. Newly planted arilbreds only get a shock treatment of 1/8 to 1/4 strength of a general water soluable fert that has been working great as a shock treatment for all my plants.

Glad to hear about your shock treatment, Anita. I will try it when I get my next order. If I am going to lose an arilbred, it is always on planting.

Could someone please clarify on when are the prime times to fertilize tall bearded iris??

I have heard several recommendations and it gets confusing.

Irisawe

In Spring when they start growing, and then right after bloom

D

our local ENCIS says to spray with foliar feed now, but I missed the 10-10-10 feed back in Febuary.

think I'll do the foliar now, assuming I can find a dry day or two. then add the granular after bloom. I picked up some 6-24-24 granular last year to use.

I agree, everyone seems to have different ideas. I like to hear them all, though, then come up with some plan to try, tweak it later if it doesn't work right. this is my second year hearing about foliar feeding, my first to try it. It's also my first year not using an expensive specialty fertilizer (Cooleys)

will have to Preen in a bit. Anita, think it will hurt anything if I fertilize first? I'm weeding as fast as I can, didn't want to put Preen down until I'd finished weeding. I'm weeding now and fertilizing as I go. was going to wait a few days before Preen-ing.

This message was edited Mar 26, 2009 6:32 PM

This message was edited Mar 26, 2009 6:32 PM

So, that means no Fall program for fertilizing? Twice in the Spring??

Because I have heard of Fall treatment. I trust you, Dee. You know what is going on.

Irisawe

I've read that Milorganite works great for daylilies. Anyone know if it is good for the iris, too?

It's probably good for most things except things you eat. I used to use it on my lawn. It was great.

It would seem you would not want to fertilize normal irises in the fall during their dormant
period but does anyone apply fertilizer in the late summer for their rebloomers?

You can google milorganite and find it's chemical analysis. From what I saw, it would not
be the best for irises. It is organic though, made from human waste by a very careful
process. There was a tv show lately, something like the dirtiest job, showing the entire
process of making it in it's generic form. Supposed to be 100% biosafe.

It is 100% biosafe except it contains a somewhat high percentage of heavy metals as does all sewerage sludge. So I don't recommend using it on things you will eat. I have never used it on iris, but as I recall it isn't so high on nitrogen -- but it probably isn't high enough on phosphorus.

Only once in the spring for me 6-24-24

I rarely feed my iris, but always intend to. Though I do plant them with lots of compost and bone meal and rock phosphate and alfalfa meal. They seem happy enough -- except for lack of water which has been serious this year. I bought some Bloom booster. Maybe I will put it on this week.

oldgardenrose, I know Cooleys highly recommends feeding irises at the beginning of fall, or about 30 days after they are planted. that's September for us. they sell different blends of fertilizer for spring and fall. like I said, this is my first year not using theirs. I can't afford it this year.

If you do fertilize in the fall, do not use much, if any, nitrogen. It will promote new growth which will soon freeze. Instead use bone meal or so something high in phosphorus.

I sort of had the same general idea about fall fertilizers. Forcing new growth to be killed
by cold winters did not compute. Phosphate and potash along with trace minerals would
probably be ok but nitrogen would only produce more dead leaves for spring cleanup.

Irises should always have a low nitrogen fertilizer.

I have come around to the conclusion that too much nitrate has been the root cause of
my problems with leaf spot. Last year, I measured leaves over 24 inches long and over
2 1/2 inches wide on some of my irises. Over and over again, books and experienced
growers say lush green growth on irises is an invitation to rot and fungus problems. I am
just a slow learner I guess.

"if you have rain and grow your irises in soil, you're going to get leaf spot." That's what Ray Schreiner told me. Same as with roses.

that is about right for here in the PNW as rain and overhead watering cause it NO MATTER how much we clean up...

D

We have it here, but not very much because of the dry climate. But we do get soft rot more than one would think!

The idea of lush green foliage causing problems is from the thick foliage shading the fan
bases and rhizomes and preventing good ventilation. I just spent two days on my hands
and knees picking layers of dead tree leaves off the centers of the clumps and clipping
dead iris leaves with a pair of scissors. There was a lot of moisture under all that waste.

I need the name of a commonly available systemic fungicide. I have used daconil which
seemed to encourage leaf spot. I have even sprayed with a 10% bleach solution which
didn't work. Maybe the iris gods are angry with me.

I plan to skip fertilizing since all my mature irises will be dug and probably given away
this summer leaving only my few oldies which are more resistant to diseases.

have you tried any of your rose leaf spot spray remedies?