Urban Food Garden

Growing Carrots

Carrots are fairly easy to grow but gardeners can run into difficulties when the seeds are germinating and the young seedlings are in the early stages of growth.  Below are some hints to help you grow good carrots.

REQUIREMENTS
  • LIGHT WELL DRAINED SOILS
  • SLIGHTLY ACID SOILS
    Though they will tolerate a relatively wide Ph range (5.5 to 7.0).
  • SEEDS NEED 12+ DEGREES C SOIL TEMPERATURE TO GERMINATE
  • EVEN SOIL MOISTURE LEVELS
    When the seedlings are young, from just emerging to two centimetres high.
  • EVEN SOIL TEMPERATURES
    When seeds are germinating.
  • PROTECTION FROM SLUGS AND SNAILS
    Though generally only in the early stages of growth, once the carrots reach five to seven centimetres in height they are usually pretty safe.
pREPARING THE BED

PREPARING THE SOIL
To grow good carrots the soil needs to be friable and well drained. Raised beds are ideal for growing carrots because they have better drainage than a standard vegetable bed.

 Add a shovelful of fine compost per square metre.   If you have heavy soil, consider adding up to a shovelful of sand per square metre to make the soil more friable.  Builder’s sand (children’s sandpit sand) is ideal, though you can also use coarser sand.

ADDING FERTILISER
Carrots are light feeders, meaning they do not need much fertiliser to grow well.  If your garden bed’s soil is in good condition, than there is no need to add any fertiliser.  If the soil is in poor condition then add a handful of blood and bone per square metre.   
You can add small amounts of animal manure but be aware that this will increase the likelihood of split roots, so generally it is not recommended.  NPK fertiliser can be added at half the recommended dose per square metre in place of or in addition to adding blood and bone. 

Turn the sand, fertiliser, compost, and soil in until its consistency is even then rake flat.

wHEN TO PLANT

Carrot seeds require soil temperatures of 12+ degrees C. to germinate. Seeds planted in soil colder than 12 degree C. are less likely to germinate and the growth rate of any seedlings that do come up will be slow, prolonging the vulnerable small seedling phase when the risk of damage from slugs and snails is greatest.

While you can use a soil thermometer to check soil temperature the best indicator that the soil is warm enough to plant carrots is when the lawn begins to grow vigorously. This will vary depending on the climate in your area, in Ballarat (where I live) lawn usually begins to grow vigorously in early to mid-October.  Of course, you can put in later plantings of carrots as the season progresses but the earliest you can plant reliably is when the lawn begins to grow.

While I think soil temperature is the most reliable way to know when to start planting carrots in your area it is also useful to cross check this by looking up a planting guide.   For more information on when to plant carrots click HERE to download monthly seed planting guides for South Eastern Australia.  

PREPARING A CARROT SEED RAISING MIX

While carrot seeds can be sown directly into the soil it is my experience that you will get a better germination rate if they are planted into a seed raising mix. You can use a standard commercial seed raising mix, but I prefer to make up my own sandier mix. Below are two homemade carrot seed raising mixes that I use.

  1. MIX 50% SIEVED COMPOST, 30% COCONUT FIBRE AND 20% SAND
    But note that as compost is not sterilised it can contain weed seeds that are likely to germinate as well.
  2. MIX 60% COMMERCIAL SEED RAISING MIX AND 40% SAND
    The advantage of this mix is that it will not contain any weed seeds.

    Note that you can in fact use any number of combinations, including other materials such as vermiculite, but whatever you end up with it should be at least as friable as a commercial seed raising mix.
PLANTING OUT A CARROT BED

There are two planting methods that I use to grow carrots.  Both involve sowing the seeds into a carrot seed raising mix. 

traditional carrot planting method *

This method produces the biggest carrots but involves more work thinning the seedlings.

  1. CREATE SMALL FURROWS 2CM WIDE, 1CM DEEP AND 20CM BETWEEN ROWS
  2. ADD 1/2 TO 3/4 CENTIMETRE OF THE SEED RAISING MIX TO EACH FURROW
  3. SPRINKLE THE SEEDS EVENLY ON TOP OF THE SEED RAISING MIX AIMING FOR TWO TO THREE SEEDS PER CENTIMETRE OF FURROW

    If you add more seeds the bed will need too much thinning, add fewer seeds and you may end up with bare patches.

  4. COVER THE SEEDS WITH ANOTHER 1/4 TO 1/2 CENTIMETRE OF SEED RAISING MIX AND LIGHTLY WATER IN.
  5. WHEN THE SEEDLINGS ARE ABOUT THREE CENTIMETRES HIGH THIN TO FIVE CENTIMETRES APART.
    A good practice is to place some of the thinning’s on their sides next to the rows to act as decoys for slugs and snails.
  6. WHEN THE SEEDLINGS ARE AROUND TEN CENTIMETRES HIGH THIN TO TEN TO FIFTEEN CENTIMETRES APART
  7. WEED THE BED AS REQUIRED
    This is best done regularly, especially in the early stages.  Mulch can be added between the rows to suppress weeds but only after the carrots have reached a height of at least 12 centimetres.

    *  Based on the Diggers planting guide distance for carrots, other planting guide recommended distances may vary slightly.

Thinning carrot seedlings using the traditional planting method.

Dominant Carrot Planting Method

This method produces carrots that are generally a little smaller than ones grown using the traditional planting method, but a dominant carrot planted bed will produce more weight of carrots per square metre of soil than a bed planted using more traditional planting distances and saves time as it requires less thinning.

  1. CREATE FURROWS 1 CM DEEP AND 6CM WIDE IN ROWS 25 CM APART *
  2. SPREAD 1/2 TO 3/4 CENTIMETRE OF SEED RAISING MIX OVER EACH FURROW
  3. SPRINKLE SEEDS ALONG EACH FURROW SO THAT THE LENGTH AND WIDTH IS COVERED WITH TWO TO THREE SEEDS PER SQUARE CENTIMETRE
  4. COVER WITH 1/4 TO 1/2 CENTIMETRE OF SEED RAISING MIX.
  5. ONLY THIN OUT IF THERE ARE VERY THICK PATCHES OF CARROT SEEDLINGS
  6. AS THE CARROTS GROW TO FULL SIZE HARVEST THE LARGER CARROTS THAT ARE DOMINATING THE OTHERS 
    By picking the largest carrots you will free up space for smaller nearby carrots to grow bigger. Keep picking the larger carrots until there are only weak straggler carrots left then clear the bed completely.  If a carrot you pick is large enough to leave a significant hole in the ground, then fill the hole with soil or compost.

    * Note that these distances are only a rough guideline. Feel free to experiment with the widths.  Indeed, when I first practiced the dominant carrot method I would sow the entire bed with seeds, but over the years I have found it helpful to have some gaps between rows.

Harvesting carrots using the Dominant Carrot Planting Method.

Traditional carrot and dominant carrot method planting distances comparison.

GERMINATING CARROTS USING A PROTECTIVE COVER

Given the right climate conditions carrots will germinate and grow in the open but they will do better if they are covered in the early stages of their growth as this offers better moisture and temperature control. It also reduces the risk of damage from slugs and snails.

For information on how to do this see Germinating Carrots Using A Protective Cover .

PROTECTING CARROTS FROM PESTS

The main threat to carrots is from slugs and snails when the carrot seedlings are first emerging.  Though cockchafer larvae can also inflict some damage.  for information on dealing with these pest see Protecting Carrots From Pests.

By using the methods mentioned above it is possible to consistently grow good sized healthy carrots.

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