Interpreting the weeds in your garden

"Your Weeds are Telling You Something! Learn to Interpret Them Here."  by gardensall   

"I was always a bit curious about why certain weeds would grow in one area and not another. Then I found out you can learn quite a bit from listening to your weeds!
Look to the Weeds
by Dianna Barker

"Gardeners and farmers constantly battle with the weeds, but weeds can have a useful purpose.  Weeds can be used as a soil indicator.  Simply by observing the most prevalent weeds that are growing in a specific area, they can indicate if the soil is acidic or alkaline, whether the soil is a healthy, balanced soil, or if it’s depleted.  Weeds can indicate a poorly draining soil, or a soil that is unable to retain moisture.  Weeds can even indicate if the soil is unbalanced, being overly rich in one nutrient and deficient in others.
When using weeds as a soil indicator, observe several of the most prevalent types of weeds to get an accurate soil assessment.  For example, the dandelion and common mullein both indicate an acidic soil, but common mullein can also mean a low fertility soil, so if you see it alone, it could mean several things, but seeing it along with dandelions would indicate an acidic soil.
Pay attention also to the health of the weeds, a healthy stand of clover could indicate a soil that lacks nitrogen, while the same weed will grow in soil that had sufficient nitrogen, but will appear much less vigorous.  It should be noted that  some weeds like purple nettle (Lamium purpureum) and Shepherd’s purse (Capsella bursapastoris) will grow on most soil types and so are not reliable indicators.  Cornflowers (Centaurea cyanus), and Hydrangeas are excellent indicators for a soil’s pH, the flowers will be pink in an acidic soil and blue in an alkaline soil.
An acidic soil is a soil with a pH below 7.0.  Look for these weeds as an indicator of an acidic soil: eastern Bracken (Pteridium aquifolium), Buggenum buttercup (Ranunculus spp.), Chamomile-German (Chamomilla pecutita), Curly Dock (Rumex crispus),  English Daisy (Bellis perennis), Ox-Eye Daisy (Chrysanthemum leucanthemum), Dandelion (Taraxacum officinale), Hawkweeds (Hieracium aurantiacum and pratense), Knapweeds  (Centaurea species),  Lady’s-Thumb (Polygonum persicaria), Mayweed (Arthemis cotula), Mosses (Musci class), common Mullein (Verbascum thapsis),  Nettles (Urtica dioica), Wild Pansy (Viola sp.), Pineapple Weed (Matricria matricariodes), Pinks (Dianthus sp.), Plantain (Plantago major),  Prostrate Knotweed  (Poly-aviculare), Wild Radish (Bapranus raphanistrum), Rough Cinquefoil (Potentilla monspeliensis),  Sheep Sorrel (Rumex acetosella), Silvery Cinquefoil (Potentilla argentea), Sow Thistle (Sonchus species), Corn Spurry (Spergula arvensis), and Wild Strawberries (Fragaria  species).  Plants that grow well in an acidic soil are azaleas, blueberries, endive, hydrangeas, rhododendrons,  rhubarb, potatoes, shallots, sweet potatoes, and watermelons.  Adding lime or using woodstove or fireplace ashes can raise the soil’s pH to the desirable pH range.
Alkaline soil has a pH higher than 7.0.  Weeds that indicate an alkaline soil are: Bellflower (Campanula sp.), Bladder Campion  (Silene iatifolia),  Wild Carrot (Daucus carota), Field Peppergrass (Lepidium virginicum), Goosefoot (Chenopodium species),  Gromwell (Lithospermum officinale), black Henbane (Hyoscyamus niger), white Mustard (Brassica hirta), Pennycress (Thlaspi arvense), Salad Burnett (Poterium sanguisorba), Scarlet Pimpernel (Anagallis arvensis), Stinkweed (Thlaspi arvense), Nodding Thistle (Carduus nutans), and True Chamomile (Anthemis nobilis).  Asparagus, broccoli, beets, lettuce, muskmelons, onions, and spinach do well in alkaline soil.  Sulfur can be added to a overly alkaline soil to lower it’s pH.
A healthy, fertile soil will have a pH of 6.2 to 7.0.  Weeds indicating a fertile soil are: Burdock  (Arctium minus), Butter Print (Abutilon theophrasti), Chickweed (stellaria media), Chicory (Cichorium intybus), Dandelion (Taraxacum officinale), Fat Hen ( Atriplex hastata), Groundsel ( Senecio vulgaris),  Lamb’s-Quarters (Chenopodium album), Pigweeds (family Amaranth), Pokeweed (Phytolacca americana),  Purslane (Portulaca oleracea), Queen  Anne’s lace (Daucus carota), and Velvetleaf (Abutilon thoephrasti).  Broccoli, corn, lettuce, melons, peppers, squash, and tomatoes are all heavy feeders and will thrive in a fertile soil.
A poor or depleted soil will have weeds such as: Broom sedge (Adropogon virginicus), Dog fennel (Eupatorium capillifolium), Wild Radish (Bapranus raphanistrum), Sheep Sorrel (Rumex acetosella), Wild Parsnip (Sium suave), Biennial Wormwood (Artemisia bennis) and Yellow toadflax (Lindaia vulgaris).  Beans, beets, carrots, legumes, parsnips, peas, radishes, sage, and thyme will tolerate poor soil conditions and perform well in depleted soil.
A heavy or Clay soil will have Bradleaf Dock (Rumex obtusifolius), Wild Carrot (Daucus carota), Chicory (Cichorium intybus), Creeping Buttercup ( Ranunculus repens), English Daisy  (Bellis perennis), Dandelion (Taraxacum officinale), Mayweed (Arthemis cotula), Milkweed (Asclepius syriaca), Plantain (Plantago major), Canada Thistle (Cirsium arvense), and Wild Garlic (Allium vineale).
Weeds that indicate a wet, poorly draining soil are:  Hedge Bindweed (Convolvulus Sepium), Bull sedge (Carex lasiocarpa), Canada goldenrod (Solidago graminifolia) Cattail (Typha latifolia), Coltsfoot (Tussilago farfara), Creeping buttercup (Ranunculus repens), Curly dock (Rumex crispus), Ox-Eye Daisy (Chrysanthemum leucanthemum), Docks (Rumex sp.), Foxtail (Hordeum jubatum), Goldenrods (Solidago sp.), Groundnut (Apios americana), Poison Hemlock (Conium maculatum), Horsetail (Equisetum arvense), Jewelweed (Impatiens pallida), Joe-pye weed (Eupatorium purpereum), Lady’s thumb (Polygonum persicaria), Marsh Mallow (Althaea Officinalis), May apple (Podophyllum peltatum), Meadow pink (Lychnis floscuculi), Meadow Sweet (Astilbe sp), Mosses (all species), Stinging Nettles (Urtica urens), Pennsylvania smartweed (Polygonum pensylvanicum), Ragwort, Tansy (Senecio jacobaea), Sheep sorrel (Rumex acetosella), Silvery cinquefoil (Potentilla argentea), Sweet flag (Acorus calamus), Tall buttercup (Ranuculus acris), Thyme-leafed speedwell (Veronica serpyllifolia), Black Willow (Salix sp.)  If you see Dock, Horsetail, Foxtails, Willows, Ox-eye Daisy, Goldenrod, Poison Hemlock, Rushes, Sedges and Joe-pye you can expect soil in that area to  experience soggy or swampy conditions at some time of the year.  Wet spots are obvious during  the rainy season but could appear fairly dry at other times. These weeds are excellent indicators that the area will be soggy at some time during the year.
Weeds that grow in sandy soils are: Arrow-leafed Wild Lettuce (Lactuca pulchella), Field Bindweed (Convolvulus arvensis), White Cockle (Lychnis alba), Cornflower (Centaurea cyanus), Dog Fennel (Eupatorium capillidolium), Goldenrods (Solidago sp.), Maltese Thistle (Centaurea melitensis), Sandbur (Cenchrus species), Small Nettle (Urtica urens), and Yellow Toadflax (Linania vulgaris).
Weeds that indicate a hardpan soil are: Field Mustard (Brassica nigra), Horse Nettle (Solanum carolinense), Morning Glory (Ipomoea purpurea), Pennycress (Thlaspi arvense), Pineapple Weed (Matricria matricariodes), and Quack Grass (Agropyron repens).  Bok choi, broccoli, cabbage, cauliflower, and mustards grow well in this type of soil.
Previously cultivated soil will have theses weeds predominately: Carpet Weed (Mullugo verticillata), Chickweed (Stellaria media), Dandelion (Taraxacum officinate), Lamb’s Quarter (Chenopodium album), Plantain (Plantago major), Purslane (Portulaca oleracea), Ragweed (Ambrosia artemisiifolia), and Rough Pigweed (Aramanth family).
Individual weeds that indicate a soil’s nutrient values are useful in determining if the soil is unbalanced.  Annual Bluegrass (Poa annua) indicates very low calcium, low humus, low bacterial count, and high magnesium levels.  Burdock grows in soils very high in iron and sulfate, and very low levels of calcium and manganese.  Buckhorn Plantain indicate very low levels of calcium, low humus levels, and very high in chlorine, magnesium, potassium, and sodium.  Common Chickweed and Mouse Ear Chickweed indicate very low calcium and phosphorus levels, and very high potassium and sodium levels.  Crabgrass indicates very low levels of calcium and phosphorus, low pH, low humus, very high chlorine levels, and high levels of magnesium and potassium.
Weeds that grow in sandy soils are: Arrow-leafed Wild Lettuce (Lactuca pulchella), Field Bindweed (Convolvulus arvensis), White Cockle (Lychnis alba), Cornflower (Centaurea cyanus), Dog Fennel (Eupatorium capillidolium), Goldenrods (Solidago sp.), Maltese Thistle (Centaurea melitensis), Sandbur (Cenchrus species), Small Nettle (Urtica urens), and Yellow Toadflax (Linania vulgaris).
Weeds that indicate a hardpan soil are: Field Mustard (Brassica nigra), Horse Nettle (Solanum carolinense), Morning Glory (Ipomoea purpurea), Pennycress (Thlaspi arvense), Pineapple Weed (Matricria matricariodes), and Quack Grass (Agropyron repens).  Bok choi, broccoli, cabbage, cauliflower, and mustards grow well in this type of soil.
Previously cultivated soil will have theses weeds predominately: Carpet Weed (Mullugo verticillata), Chickweed (Stellaria media), Dandelion (Taraxacum officinate), Lamb’s Quarter (Chenopodium album), Plantain (Plantago major), Purslane (Portulaca oleracea), Ragweed (Ambrosia artemisiifolia), and Rough Pigweed (Aramanth family).
Individual weeds that indicate a soil’s nutrient values are useful in determining if the soil is unbalanced.  Annual Bluegrass (Poa annua) indicates very low calcium, low humus, low bacterial count, and high magnesium levels.  Burdock grows in soils very high in iron and sulfate, and very low levels of calcium and manganese.  Buckhorn Plantain indicate very low levels of calcium, low humus levels, and very high in chlorine, magnesium, potassium, and sodium.  Common Chickweed and Mouse Ear Chickweed indicate very low calcium and phosphorus levels, and very high potassium and sodium levels.  Crabgrass indicates very low levels of calcium and phosphorus, low pH, low humus, very high chlorine levels, and high levels of magnesium and potassium.
Dallisgrass indicates low calcium, very high magnesium, and high potassium levels.  Dandelions indicate very low levels of calcium, and very high levels of chlorine and potassium.  Hop Clover and Oxalis indicate very low levels of calcium and high levels of magnesium.  Prostrate Spurge indicates low calcium levels and very high levels of chlorine, magnesium, potassium, and sodium.  Purslane and Mustard indicate an abundance of phosphorus.  Red Clover indicates an excess of potassium.  Redroot Pigweed indicates an abundance of nitrogen.  White Clover indicates very high levels in chlorine, magnesium, and sodium.  Wild Garlic indicates very low calcium and bacterial count, and very high levels of chlorine, magnesium, potassium, and sodium.  Yarrow (Achillea millefolium) indicates low potassium" (GARDENSALL, 2014).