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Can fertilizing a lawn be done at the same time one uses moss killer?

6 years ago

I’m preparing to do the first of the season fertilizing, and the moss in certain areas is overwhelming the hard work I did last year to plant grass in a shady area. Can fertilizing the lawn and using a bag of moss killer be done at the same time without worry of damaging the lawn?


Comments (22)

  • 6 years ago

    Wow, I didn’t know that. What about crab grass control?

  • 6 years ago

    ...and dandelion control?

    Thanks for your reply!

  • 6 years ago

    NOW is the time for dandelion control. Spot spray them with Weed-b-Gon. If you have clover or oxalis, then make that Weed-b-Gon Chickweed, Clover, and Oxalis Killer. Remember these are foliar mist, not a soil drench.

    Crabgrass is best controlled by proper watering. If you are watering more than once every 2 weeks currently, let us know, because that is too much. Proper watering can be enhanced with preemergent herbicides. Someone else can help with that.

  • 6 years ago

    I would just add that you do not need to spend money on moss killer. You can just rake it off, which you would need to do with the dead stuff anyway. So it saves you money and eliminates an extra step :-)

    If the area remains shady and somewhat moist, the moss will be a persistent problem. Select the most shade tolerant seed blend you can find but you may still need to overseed annually to keep the lawn thick enough to fend off the moss growth.

  • 6 years ago

    HU, where do you live?

    Gardengal is right. If you are properly caring for a lawn, then moss is not going to be an issue. What is your watering schedule? How often and for how long are you watering?

  • 6 years ago

    Although it is fun to watch the moss die, let's face it, and make it easier to rake off if you have a large mat of moss. Living moss can be stiffer stuff. Dead mosses are wet, easy to tear things that you can actually seed directly into in fall if you want.

    I kill mosses on the patio because removing them requires far more effort and tears out the sand, which I then have to replace. I don't mind the look of decaying moss--I feel it adds character--so a drop or two of homemade 3-8% iron sulfate and I'm good to go. But I also don't let it get to the "standing hammock of moss" that some do in the patio cracks. :-)

    Mosses do tend to favor more shady and/or wetter areas, and both can certainly be an issue when growing grass. So what Big D asked.

  • 6 years ago

    NW PA (Erie). Medium to dense shade area In the front yard. Never water unless grass seed is planted. Overseeded bot front and small backyard the past 2 years. Bought special seed from local lawn care supplier company For both Shaded areas and sun and shade, and use common Scott’s fertilizer 3-4 times a year. 2 huge (6’ diameter) Oak trees in front yard, minimal sun in morning, rest of morning and into late afternoon dense shade, some minor sun late afternoon to sipper time. Moisture in some areas a big contributor In my view to the moss situation. Crab grass is mostly under control but persistent In certain areas. Dandelions are spotty at best, so past fertilization’s has worked. Clover in back yard is a problem, thanks for the information on that, but I’m more interested in the front yard, thickening up thin areas of grass. I’ve been raking the moss every spring. I bought the bag of moss remover so it would permanently be removed, it looks like from comments above that most likely won’t happen. It was an inexpensive ($14) purchase so I’m not out a lot of money.

    Thanks for all of your comments, more information you can provide is most appreciated.

  • 6 years ago

    " Oak trees in front yard, minimal sun in morning, rest of morning and into late afternoon dense shade, some minor sun late afternoon to sipper time. "

    It sounds like you are going to have a tough time encouraging a lawn to grow in this area. Even the most shade tolerant cool season blends need at least 4 hours of sun to grow well. Perhaps there is a possibility of limbing up the oaks to allow more sunlight to the area. If not, then maybe a more shade tolerant type of groundcover could be planted in those areas, leaving the lawn to the sunnier locations.

    If you can't fix the shade, the moss will be a recurrent problem. Any moss killer will be a very temporary fix. It is not even a permanent fix under the best of circumstances!

    HU-720265407 thanked gardengal48 (PNW Z8/9)
  • 6 years ago

    Embrace the moss. And maybe some bleeding hearts in spring and deep shade stuff in summer... :-) At least moss is a pretty green...

    Deep shade, and under trees, is never a good environment for grasses. I can--and do--work with 100% shade, but it does get north light and reflection off a white wall, so it's a bit of a special circumstance, and decidedly not a deep puddle of shade under a grove.


    You might be able to return the moss killer. Or, if you let us know what's in it, you might be able to use it anyway on your lawn. Ferrous sulfate moss killers green up existing lawns quite nicely if you choose not to use them as moss killer. Others have other potential uses about the house and gardens depending on their constituent chemistry, purity, and other ingredients.

    Ask me about the amount of creative chemistry I can do just in the kitchen, laundry room, easel/palette, bathroom, and garden.

    HU-720265407 thanked User
  • 6 years ago

    From my experience crabgrass can be stopped by applying a pre-emergent which works by preventing seeds from germinating. It's getting late for this so you need to apply it NOW, if not yesterday.

    Moss can be slowed by applying lime. You need to use a pulverized lime thick enough that you see a light white coating over the entire lawn. Applying pelletiized lime is so expensive that you'll never get enough to make much of a difference. That is used by those who want to get in and out and get paid. Only use lime if you live in an area with acid soil.

    Grass can be grown in shade if you force growth with extra fertilizer. If you over fertilize you must also mow more.

    If you have grass under large trees, especially large oak trees you have to realize that when the trees are leafed out they are in reality a huge umbrella. The only water the lawn will get is what you provide.

    HU-720265407 thanked John D Zn6a PIT Pa
  • 6 years ago

    Lime has NO effect on lawn moss. While it will often grown in acidic soil conditions, it will also grow in very basic to alkaline soil conditions if other factors - like heavy shade - are right. You are just being hoodwinked if someone tells you liming your lawn will cure it of moss :-)

    HU-720265407 thanked gardengal48 (PNW Z8/9)
  • 6 years ago

    I'm going from MY EXPERIENCE! I am not going to hoodwink someone with my free advice, and the bag of lime is very inexpensive. Hardly a hoodwinking!

    By the way; you can apply fertilizer and lime at the same time.

    HU-720265407 thanked John D Zn6a PIT Pa
  • 6 years ago

    John, the point is lime does nothing to deter moss growth if other conditions are present that will allow it to flourish. That's what I meant about hoodwinking. A lot of lawn care companies will tell you you need to apply lime to get rid of the moss, which it won't do. And there is no need to apply lime if it is not necessary to lower pH. Most cool season grasses prefer a slightly acidic soil anyway so liming is really only necessary if the pH of your soil is below 5.5 to 5.8.

    And if you are using the lime to raise pH (not just to maintain it at a proper level), then applying lime and fertilizer together is not advised. If excessively acidic, the lawn will not realize much benefit from the fertilizer and because the reaction of the lime to lower pH takes time, it is suggested to apply the lime first, wait several weeks and then fertilize.

    HU-720265407 thanked gardengal48 (PNW Z8/9)
  • 6 years ago

    OP said in his first sentence:

    " I’m preparing to do the first of the season fertilizing, and ......"

    Assuming he's correct and has moss then applying that fertilizer with lime is recommended; assuming he has acidic soil.

    I responded to this thread because no one recommended the obvious crabgrass solution not because I want to respond to every thread on this site. In the last thread where you argued your moss solutions the OP decided to follow my advice, and you stated raising the PH has no effect on fertilizing.

    HU-720265407 thanked John D Zn6a PIT Pa
  • 6 years ago
    last modified: 6 years ago

    Again with this?

    Well, actually, mosses do tend to prefer a pH on the acidic side. They don't really mind one slightly on the alkaline side, of course, but the one thing they really don't like is having most metals applied atop them. Nor saltier conditions, which desiccate them very easily, of course.

    So applying dolomitic lime onto them could lead to magnesium toxicity quite easily, as well as sop up excess liquids. Since most limestones aren't anywhere near pure, you're also applying any other metals that were in there as well. I'd have to experiment.

    That comes from my four billion years of experience, which I believe beats other people's thirty years, so shut it. I can therefore demand far more respect due to my superior, but of course equally unproven, experience. Nyah.

    John, let it go. In her eyes, she's right, you're wrong, she's more experienced, and you're a peon. It's wise to realize she's not worth it and go on with your life. Have some fun poking at her when she only sees black and white, and laugh at her otherwise.

    Yes, adding lime can get rid of moss via an indirect process where adding calcium (not dolomitic lime) loosens the soil, opening it up and increasing the drainage by widening the pores in the soil. That encourages more air, which increases bacterial action, and so on, over time, which drains the soil, decreasing water in it, and removing the tendency for mosses to form. Which they'll happily do in full sunlight if it's wet enough--I can offer, as proof, my back patio!

    Similarly, raising (or lowering, although that approaches the impossible) a pH from the wildly inappropriate into something that will grow a good lawn can abolish mosses (or other invading plants) by the process of allowing grasses or other plants to flourish. Mosses, quite simply, cannot compete with grass if grass can dominate in that area.

    You can do the same by opening the soil with any good soap product or increasing aeration using organic material.

    It's not wise to fertilize with a urea-based fertilizer that you're not going to water in or have rain on pretty fast and lime at the same time due to the loss of nitrogen to the air, but again, that "urea" part is critical and left out (of course) in her explanation above.

    If it rains within 3 days? Fine. Watering it in shortly? Fine.

    Letting it go a week or more? You'll lose about 15% of the nitrogen to the air or so. Maybe.

    You can use organic fertilizers with complete abandon when you lime. It's fine. They don't work the same way anyway.

    So that fertilizer part? A half-truth at best and another example of black and white thinking that's only partially explained.

    HU-720265407 thanked User
  • 6 years ago

    Thank you, the answers make sense, such as complete grass covering areas (which is what I’m trying to accomplish) reduces moss growing opportunities. Since I don’t have the money to re-sod, I have to work with what I have. I also have a broadcast spreader, which I see now was a mistake to purchase....meaning the recommended settings given on the bags of material to be spread over the lawn (which I followed exactly in the past) for effectiveness must be increased, or....buy, rent, borrow, or steal a decent drop spreader. I’ll check back tomorrow (Saturday) before noon, as by then it will warm up enough to get busy. We have plenty of rain in the local weather forecast for the next 7 days after tomorrow which is to my advantage, whether seeding, overseeding, liming, or fertilizing, reading from above. Thank you all for replying...I’m learning a lot from every post.

  • 6 years ago

    A broadcast spreader tends to make fertilizer applications easier as you tend to see any gaps between passes with the drop spreader.

  • 6 years ago

    Apologies as this is only partly on topic, re: moss and ferrous sulphate (but not about lawns). I've found ferrous sulphate to be the only effective treatment for our basketball area - heavy moss, shaded area, slippery if the moss not treated. But I also have heavy moss on some parts of my roof. I don't expect to ever be able to remove the moss completely but do want to keep it from being a four-inch thick carpet. Some areas I have removed by hand to keep it under control. Other parts just aren't accessible - too high and steep sections. Even getting buckets of water up there for mixing ferrous sulphate is a serious challenge, and simply pouring diluted mix on semi-vertical sections, well, I reckon most will run off before it can do anything to the moss. (Note I do have access to and can walk on the parts of the roof that have a modest pitch, but it drops off to a very steep pitch at the edges which is where the problematic moss is).

    Just wondering if anyone has suggestions on how to apply/treat in such areas or how they've dealt with such cases.

  • 6 years ago

    Broadcast spreaders are wonderful! I only use one myself, that I repair repeatedly because I'm cheap. I mean frugal. Anything you can do with a drop spreader you can do with a broadcast, except edge applications, which can be done by (gloved) hand.


    You may not want to fertilize at this point, however, on a northern lawn as the correct time to do so is Memorial Day. Fertilizing in April sets off even more top growth than you already have, and that taps the roots of carbohydrates, which weakens them and costs you in terms of summer growth. Ultimately, it thins out the lawn.

    So if you do anything today, apply the lime--if a soil test told you that you needed it. If not, I'd be inclined to get one before doing anything. But you can use the moss killer if you really want to, it won't hurt anything even if it's unnecessary, strictly speaking. Although, as noted, quite a lot of fun.

    HU-720265407 thanked User
  • 6 years ago

    Armoured--I wouldn't have any problems recommending ferrous sulfate for the basketball area, of course. But I'm not at all sure about the roof! It's extremely acidic even when diluted to 5%, and the granular, when initially rained on...whew.

    I'd be inclined to contact a roofer and see what they have to say about application before doing anything. I have a feeling the shakes aren't going to tolerate it well but hopefully I'm wrong.


    A quick search online shows that the services of roof cleaners are quite common. :-)

    Zinc sulfate monohydrate comes up quite commonly as a better moss killer for roofs. This one makes me far more comfortable.

    Bayer apparently makes a 2 in 1 killer that's potassium soap-based. This absolutely makes me comfortable. I'm a soap maker and completely understand the product. It dessicates the moss AND dessicates and poisons it with potassium. But potassium is harmless to you (you need tons of the stuff) and your plants and grass both need tons of it as well. The soap part is biodegradable and becomes food for your plants. With some good water pressure, you could apply this from the ground.


    Here's a great article.

  • 6 years ago

    @User, thanks for the info. Looking into, it will make more sense to hire someone. I was sort of hoping something I could do a lot of myself while stuck at home (virus lockdown), but it can wait. After all, it has for a few years now.