Garden of Weeden - Ask Extension
I recently bought a 100-yr-old house with a large yard that seems like no previous owner has ever tried to tame, at least not for a couple decades. Th...
Knowledgebase
Garden of Weeden #859587
Asked February 21, 2024, 2:52 PM EST
I recently bought a 100-yr-old house with a large yard that seems like no previous owner has ever tried to tame, at least not for a couple decades. The weeds are monstrous. In years before I bought the house and started to whack them to keep them short, I'm told the weeds would reach higher than the fence. Right now, the space is a layer of dead plant matter from winter, a layer of dense clay soil full of weed dormant weed seeds, and deeper layers full of live roots several feet deep. (Luckily there are no underground pipes or wires as they are all under my duplex neighbor's side). I have so many questions because I just don't know where to begin. I would like to tame the yard in a cost effective way before I consider major landscaping. The yard is mildly uneven and has a slight slope towards the alley, so some leveling is needed. But how do I go about replacing the mass of weeds with something that can be walked on and enjoyed? Clover sounds great to me as a start, or a low-maintenance recommended native grass. But before sowing or planting, what steps do I need to take to prepare the land? Do I rent a massive tiller and then have it leveled, or have it leveled and then tilled? Do I need to remove as much dead weed matter as possible first? How do I sow clover or grass seed so that it blocks the dormant weed seeds? After getting ripped off by a landscape "designer" who promised to advise me, I could really use some unbiased advice. Even searches on YouTube don't really provide how-to videos that match my situation. I really appreciate any tips you can share or resources your team can point me to.
Couple things to note: Full sun May-Oct. All concrete walkways removed, though another concrete post-hole or sidewalk piece may still be lurking beneath the mud. No gas or electrical underground to worry about. Photos attached do not do justice to how tall and thick these weeds get.
Denver County Colorado
Expert Response
[Garden of Weeden - ha ha!]
Wow! You’ve got a lot on your plate. Instead of trying to address all the issues, start with the main problem which is weeds. Don’t jump the gun and start planting before you have the weeds under control.
In one way you are lucky to be able to start with a blank slate. You can do things the ‘right’ way instead of trying to fix others mistakes. First, clear away all the debris and dead plant material. Then we suggest you get a soil analysis to know what you’re working with (for a small fee). This will help you to choose type and amount of soil amendments down the road. Here’s a link to the CSU Soil Lab:
https://agsci.colostate.edu/soiltestinglab/
You’ve got options for controlling weeds. To control annual weeds, those that come up each year from seed, you could apply a pre-emergent herbicide to prevent those weed seeds from germinating. From your photos, it is apparent you have large and deep 'seed bank' of seeds that have accumulated over time. Each time you till the soil, you will be exposing a new crop of weed seeds to sunlight and moisture It will take time to deplete that seed 'bank.' You can speed the process by using a rototiller or other mechanical cultivator, or manually turning the soil to raise a lot of seeds, wait for that first crop to sprout, then kill them and repeat the process several times.
You can also apply a pre-emergent but only if the timing is right. Pre-emergents need to be applied before seeds germinate, generally late April to early May. Timing is key and with our unpredictable weather, it can be hard to predict. Be mindful that if your plan entails starting new plantings from seed, you won't want to use a pre-emergent for the weed seeds because it will inhibit germination of desirable seeds as well as undesirable seeds. If do use one, be sure to read and follow the label instructions before use.
You also can try solarization which is a method of killing weeds using heat from the sun. Avoid solarization around desirable plant and tree roots. This method needs proper timing, too, because you need the hot summer sun to heat up the soil adequately. Here’s a quick description of this process:
1. Remove vegetation and cultivate the soil to a six inch depth.
2. Sprinkle irrigate the area.
3. Cover the area with 4 mil clear plastic. Bury/secure the edges of the plastic all the way around the plot.
4. Leave in place for at least three weeks during the hottest days of summer (July and August are best).
5. After removing the plastic, avoid additional deep cultivation that would bring up new weed seeds from deeper soils.
There are chemical herbicides you can use which kill a broad spectrum of weeds and grasses. There are many on the market, but choose a non-selective herbicide containing the chemical Glyphosate which will kill both broad-leaf and grassy weeds. This would need to be applied to the weeds while they are actively growing - there's no point in spraying weed debris. Whenever using any chemical herbicide, you must read the label before using it and follow the label instructions.
Other methods of controlling weeds include manually pulling, mulching, mowing, weed barrier, etc. Click on the link below to provide unbiased, research-based information on the different methods and their pros and cons to choose the method that is right for you.
https://cmg.extension.colostate.edu/wp-content/uploads/sites/59/2020/03/Weed-Management-for-the-Home-Lawn.pdf
Weed control is a process; don’t be surprised if it takes you more than one growing season to get your weeds under control. It will be worth it in the long run. Soil preparation is key to successful gardening and avoiding headaches down the line. You can use the time to work out ways to create a plan to follow to deal with the issues you mentioned. I hope you look to Colorado State University Extension for more guidance. We are a really great source of information.
https://cmg.extension.colostate.edu/
Good luck in your future endeavors.
Wow! You’ve got a lot on your plate. Instead of trying to address all the issues, start with the main problem which is weeds. Don’t jump the gun and start planting before you have the weeds under control.
In one way you are lucky to be able to start with a blank slate. You can do things the ‘right’ way instead of trying to fix others mistakes. First, clear away all the debris and dead plant material. Then we suggest you get a soil analysis to know what you’re working with (for a small fee). This will help you to choose type and amount of soil amendments down the road. Here’s a link to the CSU Soil Lab:
https://agsci.colostate.edu/soiltestinglab/
You’ve got options for controlling weeds. To control annual weeds, those that come up each year from seed, you could apply a pre-emergent herbicide to prevent those weed seeds from germinating. From your photos, it is apparent you have large and deep 'seed bank' of seeds that have accumulated over time. Each time you till the soil, you will be exposing a new crop of weed seeds to sunlight and moisture It will take time to deplete that seed 'bank.' You can speed the process by using a rototiller or other mechanical cultivator, or manually turning the soil to raise a lot of seeds, wait for that first crop to sprout, then kill them and repeat the process several times.
You can also apply a pre-emergent but only if the timing is right. Pre-emergents need to be applied before seeds germinate, generally late April to early May. Timing is key and with our unpredictable weather, it can be hard to predict. Be mindful that if your plan entails starting new plantings from seed, you won't want to use a pre-emergent for the weed seeds because it will inhibit germination of desirable seeds as well as undesirable seeds. If do use one, be sure to read and follow the label instructions before use.
You also can try solarization which is a method of killing weeds using heat from the sun. Avoid solarization around desirable plant and tree roots. This method needs proper timing, too, because you need the hot summer sun to heat up the soil adequately. Here’s a quick description of this process:
1. Remove vegetation and cultivate the soil to a six inch depth.
2. Sprinkle irrigate the area.
3. Cover the area with 4 mil clear plastic. Bury/secure the edges of the plastic all the way around the plot.
4. Leave in place for at least three weeks during the hottest days of summer (July and August are best).
5. After removing the plastic, avoid additional deep cultivation that would bring up new weed seeds from deeper soils.
There are chemical herbicides you can use which kill a broad spectrum of weeds and grasses. There are many on the market, but choose a non-selective herbicide containing the chemical Glyphosate which will kill both broad-leaf and grassy weeds. This would need to be applied to the weeds while they are actively growing - there's no point in spraying weed debris. Whenever using any chemical herbicide, you must read the label before using it and follow the label instructions.
Other methods of controlling weeds include manually pulling, mulching, mowing, weed barrier, etc. Click on the link below to provide unbiased, research-based information on the different methods and their pros and cons to choose the method that is right for you.
https://cmg.extension.colostate.edu/wp-content/uploads/sites/59/2020/03/Weed-Management-for-the-Home-Lawn.pdf
Weed control is a process; don’t be surprised if it takes you more than one growing season to get your weeds under control. It will be worth it in the long run. Soil preparation is key to successful gardening and avoiding headaches down the line. You can use the time to work out ways to create a plan to follow to deal with the issues you mentioned. I hope you look to Colorado State University Extension for more guidance. We are a really great source of information.
https://cmg.extension.colostate.edu/
Good luck in your future endeavors.
Thank you so much for the thorough response! So many things to consider but it's clearer now. I have just a few follow-ups:
In your solarization instructions, the last step notes to avoid deep cultivation afterwards. Am I right in assuming this means I should probably get the land leveled the way I will ultimately want it before I solarize, because any leveling work after solarization would just stir up the new seeds?
If my above assumption is correct, then I think my process will be:
- Remove dead vegetation
- Level and fill-in
- Spray pre-emergent herbicide
- For whatever gets past the pre-emergent, spray glyphosate as its growing
- Rototill to stir up seed bank
- Spray more glyphosate on whatever starts growing
- Repeat steps 5 and 6 until mid-summer to cycle up the seed bank
- Solarize in July-August
I was also thinking about clover as a strategy for weed control (and it looks nice among other benefits). It sounds like clover can really outcompete a lot of weeds with its dense roots and clumping characterstics. Do you have any tips for using clover as a weed control strategy in my situation? How might it fit in with the above process?
Thanks again!
Once you have cleared away all the old debris, maybe even mowed the area, amend your soil based on the recommendations obtained from your soil test which will necessarily involve cultivating 6-8" deep and will bring up a lot of weed seeds. After the amendment is incorporated, level the area to your finish grade. At that point, lay down and secure the plastic for solarizing which will destroy both annual and perennial weeds; no need for a separate pre-emergent step.
Down the road, you most likely will have to go back in either with a pre-emergent next spring for the annuals or glyphosate for the deep-rooted perennials. It will get easier and there will be fewer and fewer weeds to tackle each year you stick with it.
Down the road, you most likely will have to go back in either with a pre-emergent next spring for the annuals or glyphosate for the deep-rooted perennials. It will get easier and there will be fewer and fewer weeds to tackle each year you stick with it.
Hello! Since the previous conversations on this thread, I've made some headway in my weed control process. I removed the dead vegetation, did a bit of shovel-leveling, turned up the soil as deeply as I could with a rear-tine tiller, and then dropped pre-emergent (Preen) on it right before a good rain in late April. Aside from having to glyphosate-spray some deep-rooted perennials coming up (bind-weed, I think), this yard looks pretty good for the next steps of weed control (pic attached). I also got my soil test results back from CSU (attached) and it looks like the only recommended amendment is nitrogen. What would you recommend for that?
I hope to get your advice on the next steps of my "Garden of Weeden" transformation plan, which are:
1. Order soil amendments
2. Till amendments into soil while turning up more seed bank deposits
3. Grade/level the yard to my final design specs
4. Sprinkle water and lay down plastic to solarize during mid-summer
5. Seed grass or clover, or lay down sod for desired lawn patches in the fall (most of the yard will be xeriscaped with gravel and rock) in hopes that a patch of green will get a head-start for next year and suppress weeds directly below it.
6. On non-lawn areas to be xeriscaped, continue weed control practices (tilling and pre-emergent herbicide) through next spring to bring up more seed bank deposits.
7. Layer rocks/gravel/pavers/etc. on those areas next summer.
Do you have any suggested changes for these steps? Am I rushing it in terms of weed control by trying to get some small lawn areas installed by this fall and xeriscaping materials applied on the rest of the dirt by next summer?
One other variable is that I just bought my neighbor's side of this duplex I live in, and that side has good landscaping with a nice lawn and a zoned sprinkler system. I may simply extend that system over to my current side while the ground is simply dirt. Where in my above process would you suggest I incorporate this installation? Not that I have any cash left over to do any of this after buying that property.
Thank you for any guidance you can offer!
Thomas, you have been busy! Most pre-emergents herbicides last between 8-12 weeks, some shorter and some longer. You said that you applied Preen at the end of April which would take you to the end of June or July before you should begin planting. Check the Preen label for recommended length of time between application and planting.
Even though you have made great progress, here is a link to a CSU Fact Sheet on renovating the lawn. Not all of it applies to you because you are wanting to plant more than grass. However, it takes you through the steps again to eliminate weeds/grass before replanting :https://extension.colostate.edu/topic-areas/yard-garden/renovating-the-home-lawn-7-241/
You mention that you'd like to consider planting clover. Clover has gained traction as an alternative to a grass lawn. Here is a link to an article published by the University of Maine about the suitability of clover for a lawn that might help you with your decision: https://extension.umaine.edu/gardening/2023/02/14/is-white-clover-suitable-for-lawns/
As for the irrigation question, CSU has a Fact Sheet on home irrigation systems. You might need to talk to someone familiar with sprinkler systems to make sure that when you extend the lines you have sufficient pressure to operate the system properly. Here is a link to the irrigation Fact Sheet: https://extension.colostate.edu/topic-areas/yard-garden/operating-and-maintaining-a-home-irrigation-system-7-239/
I was not able to open the link to the results of your soil test. However, mixing good compost into your soil may be all you need to amend the soil to an acceptable nitrogen level. Here is a link to a CSU Fact Sheet on fertilizing the garden: https://extension.colostate.edu/topic-areas/yard-garden/fertilizing-the-vegetable-garden-7-611/
This is a lot of information for you to take in. Let us know if you have any more questions.
Even though you have made great progress, here is a link to a CSU Fact Sheet on renovating the lawn. Not all of it applies to you because you are wanting to plant more than grass. However, it takes you through the steps again to eliminate weeds/grass before replanting :https://extension.colostate.edu/topic-areas/yard-garden/renovating-the-home-lawn-7-241/
You mention that you'd like to consider planting clover. Clover has gained traction as an alternative to a grass lawn. Here is a link to an article published by the University of Maine about the suitability of clover for a lawn that might help you with your decision: https://extension.umaine.edu/gardening/2023/02/14/is-white-clover-suitable-for-lawns/
As for the irrigation question, CSU has a Fact Sheet on home irrigation systems. You might need to talk to someone familiar with sprinkler systems to make sure that when you extend the lines you have sufficient pressure to operate the system properly. Here is a link to the irrigation Fact Sheet: https://extension.colostate.edu/topic-areas/yard-garden/operating-and-maintaining-a-home-irrigation-system-7-239/
I was not able to open the link to the results of your soil test. However, mixing good compost into your soil may be all you need to amend the soil to an acceptable nitrogen level. Here is a link to a CSU Fact Sheet on fertilizing the garden: https://extension.colostate.edu/topic-areas/yard-garden/fertilizing-the-vegetable-garden-7-611/
This is a lot of information for you to take in. Let us know if you have any more questions.
