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Weeds

Recognising Common Garden Weeds – Annual Weeds

recognising oxalis annual weed

Speedwell annual weed header

Of course weeds are a large part of our gardens and are plants we have to keep an eye out for especially before they manage to sow seed and multiply. If you do keep a strict and thorough weeding regime and keep the spread of seed to a minimum this particular chore will get much easier as the years go by. You will also find by using a ‘do dig’ method and adding compost and manure to the surface of your garden rather than digging it in you will reduce them amount of dormant weed seeds brought to the surface to germinate.

Some of the most difficult weeds to get rid of are the annual varieties as they are such prolific seeders and grow so quickly, I have included the most common varieties below including photos and descriptions. I general I have shown them in their more immature state as this is the point you will need to recognize them and get rid of them.

recognising chickweed

Chickweed
Chickweed grows to about 5-7 cm high and has a vigourous spreading habit, small white flowers and an extensive root system.

Chickweed is probably the most common annual garden weed. Seeds germinate easily in damp soil in Spring and Autumn or throughout the Summer in a wet year.

Chickweed sets seeds quickly so remove any seedlings you see by hoeing in dry weather or pulling by hand if soil is too damp to hoe. Each plant produces 2,500 to 15,000 seeds which ripen five to seven weeks after the parent plant germinates. Plants are hardy so will survive mild Winters where it can take off quickly and set seed in Spring before you notice!

recognising fat henFat Hen
Fat Hen grows us to 27cm high with broad leaves and small indistinct green/white flowers. Related to tree spinach, fat hen was eaten as a vegetable in neolithic times and is rich in vitamin C.

Fat Hen is found on rich soil so is commonly found in the vegetable garden. Seedlings germinate in dense patches and look harmless at first but quickly grow into large plants if allowed to remain.

Hoeing seedlings when small is the easiest method of control, usually twice if large numbers of seedlings have germinated. Seeds persist for a long time in the soil and will germinate readily even after 20 years when brought to the surface.

ewcognise weed charlockCharlock
Charlock is a common weed when ground is disturbed and grows up to 60cm high with yellow flowers. You will often see large patches of charlock which can easily be confused with the oil seed rape due to its sea of yellow flowers.

Seed are set in 8-10 weeks and will germinate in nearly all seasons especially in Spring. Charlock is a fast growing weed of the brassica family and is easy to how when young or easy to pull our if allowed to grow a larger plant. As with all annuals remove before it can set seed or it will become a much bigger problem. Remember as it is a brassica it can harbour pests and disease from that family so needs to be kept out of other crop rotations.

recognising groundselGroundsel
Groundsel grows to 5-22 cm high, it has lobed leaves and small yellow flowers that form seed heads similar to dandelions.

Groundsel sets seed within 4-6 weeks so you need to be vigilant, one small plant will set hundreds of seeds dispersed over a wide area by the wind. Seeds will germinate throughout the year apart from mid winter and will quickly establish on fertile soil.

If soil is dry or shady the plants will set seed when young so keep an eye out under shade plants like parsnips, courgettes or cabbage. Remember to remove any flower heads after hoeing as they will still make viable seed even if left uprooted on the soil.

Recognise common fumitory weedCommon Fumitory
Common Fumitory grows to a height of 10 to 40cm on long slender branched stems. The stems support light, feathery leaves and numerous purple-pink flowers.

Fumitory likes undisturbed ground so will be more common on the verges of your garden where the delicate pink flowers are very attractive. The plant is easy to control by hoeing and while it seeds remain viable for a long period of time it is not considered as a particularly invasive weed.

recognising hairy bittercressHairy Bittercress
Hairy bittercress is a compact plant growing 3-5cm high with tiny white flowers.

Seeds are set in 4-6 weeks with an explosive seed mechanism by which seeds can be dispersed up to 1m (3ft) away or considerably further if carried by the wind. The diminutive size of the plant also makes it easy to miss allowing it to scatter its seeds unnoticed.

Bittercress is a weed of cool moist conditions so improving drainage will help control. It is also commonly seen growing on the surface of compost in nursery plants and can be unwittingly introduced to gardens from container grown plants.

Identify sow thistlePrickly Milk (Sow) Thistle.
Can grow up to 90cm high but often smaller with pale yellow flowers.

Seeds are set in as little as four weeks if the plant is in a dry and shaded position. Sow thistle needs to be spotted and removed early as if has a strong tap root making it difficult to eradicate when established and will set hundreds of seeds.

Sow thistle will germinate in a wide variety of conditions throughout the year, even over winter in mild years. There is also a similar perennial sow thistle whose fleshy roots are quick to colonise but can be easily removed as seedlings to keep them under control.

recognising oxalis annual weedOxalis
Oxalis only grows about 5cm high but is a very prolific seeder. I had some in my tunnel a coupe of years ago and quite liked the look of is so left it be, big mistake as it’s now all over the place.

Seeds are dropped from barely visible pods before you even notice it’s presence. You need to keep your eye out for this one because once present it will multiply very quickcly. Oxalis is often an unwanted passenger in nursery plant pots.

Recognising Shepherds PurseShepherds purse
Shepherd’s purse consists of a cluster serrated leaves with a long slender flower head 5-10cm tall. Before they produce their flower stem Shepherd’s purse can be easily confused with a dandelion leaf.

Seeds are set in 6-8 weeks in green heart shaped seed pods (or purses, hence name). Once the flower stalk has been produced the plant will have grown a deep tap root which can be difficult to remove. Like most weeds, it is a good idea to hoe young seedlings early.

recognising speedwellSpeedwell
Speedwell is a ground hugging Spring and Autumn weed with prostrate foliage and pretty pale blue flowers.

I have a mat of speedwell under a beech tree on my lawn and am quite happy to leave it there, its low growth habit means it survives the mower.

Speedwell sets seeds in 4-6 weeks but is easy to control by hoeing or pulling out when small. Plants become more difficult to get rid of if allowed to grow into larger clumps but this is unlikely in a busy vegetable garden.

20 comments
    1. Andrew

      Hi Maeve
      Yes, they have great names don’t they. You shouldn’t find it too difficult to get rid of by cutting the tap root before it seeds. Good luck!

  1. Helen Bond

    I actually bought oxalis from a company called future primitive plants!!! It was in my sunroom, now it’s on the top of every pot in there. The mother plant has been eradicated but the seed spread by pods exploding is amazing. I think I might have it for life.

    1. Andrew

      Hi Helen

      Yes you might be stuck with it alright but as we’ve all said it is a dainty little thing so easy to forgive. Have a great season. Andrew

  2. Elizabeth Cleary

    You won’t believe this, but I have made several attempts to cultivate that little brown-leaf oxalis, and it keeps dying off. Nature can be very contrary sometimes!

    1. Andrew

      H Elizabeth. It’s funny isn’t it? They absolutely love it in my polytunnel anyway, I can’t get rid of them. They seem to like it on the dry side if that’s any help cultivating them.

  3. Eve McKay

    Very informative. Thank you for sharing. I moved to Ireland from the uk many years ago and transported a lot of potted plants with me. Like yourselves I thought the oxalis was pretty so left itBig big mistake. It’s all over my tunnels now, along with bittercress and chickweed. Any help in eradicating them would be good. Thanks Eve

    1. Andrew

      Hi Eve. I am afraid you just have to keep removing them before they flower. I don’t want to depress you but the old adage ‘1 years seeding means 7 years weeding’ holds true. Keep a strict weekly weeding regime and you will soon gain control. Also mulch rather than digging over the soil to avoid bringing dormant seeds to the surface. I hope this helps. Andrew

  4. Alice Hanratty

    I’m trying to identify a weed in my garden. I was told it was colt’s foot but it isn’t .it has a similar leaf but bigger grows to about 3 ft or more with pale purple flowers and becoming quit thick in the stem at which point it can be pulled up. it has a wide ranging white route system with 1000s of new hairy bits I suppose getting ready for next year. It has a noticable sour smell from the leaves when dug up long before it flowers. My garden is in the Dublin nth. city centre and though the surrounding gardens are not at all cared for it has’nt spread to them. The leaves can grow to about 4×3 inches.

    1. Andrew

      Hi Alice. Apologies for the late reply, would it be possible to send us a photo of the weed so I can help identify it? What shape are the flowers? Andrew

  5. Lisa

    Hi
    I just wondered if there was a way I could identify a plant that’s growing in my flower bed..I’m fairly positive its some sort of weed but as I’ve never seen it before this year in my garden I wasn’t sure..I have now got three of them and as I sometimes throw around a few seeds to see what grows I left them alone in case they might be a flower..they are now about a foot or so tall with very light colour leaves .The leaves are unusual and curly in places but remind me of cacti also..there are buds formed which are now drooping and look as if they are going to be purple..although it does look like a weed I don’t want to pull them up till I’m sure ..I’ve checked several websites pictures Etc and have come across nothing even remotely like them..if I sent a picture of them could they be identified?
    Thank you so much for taking the time to read this
    Lisa Quirke

  6. Alice Hanratty

    I contacted you some time ago re weed identity and you replied seeking a photo of it which I sent but nothing further from you. Any luck since? Alice Hanratty

    1. Andrew

      Hi Alice. Sorry I didn’t get back to you sooner about the weed. I did have a look at the photos but I am afraid I drew a blank. Can you send a photo of the whole plant rather than just the leaf, also some context to get an idea of size would be great. Andrew

    1. Andrew

      Hi Peter

      Weeds are just plants in the wrong place. If you like them you have a nice cottage garden, if you don’t you have a mess of weeds. I have a cottage type garden myself and have plenty of flowering weeds which I leave well alone. Who cares if they look nice?

      Andrew

  7. KATHLEEN SMITH

    I have the Oxalis in my gravel front yard – prolific to say the least. I have found that being diligent with vinegar/salt/soap mixture works well, on a sunny day it works best. I spray not only the surface plant but give the root area a really good shot. 1 gal vinegar, 1 cup rock (pool) salt, 1 tbsp soap. It is obvious to me that some seeds were sent out from the pods last year so doing my best to get them while they are before or still flowering.

    1. Andrew

      Hi Kathleen. Thank you for your comment, that is very helpful advice. Do you use high strength catering vinegar? Where do you get the large quantities you need?
      Andrew

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