grow from seed

  • Grow at Home: Asparagus

    What it is

    Asparagus (Asparagus Officinalis) is a perennial flowering plant species in the genus Asparagus. It is long lived and once established the plants can last for 20 to 30 years.   Its young shoots are a much sought after spring vegetable.

    Types

    Asparagus_spears_in_soil

    Asparagus is either male or female. The male plants produce more plentiful and larger spears so gardeners often prefer them.  The female plants expend a huge amount of energy producing seeds and so provide less for your table.

    In the past all asparagus varieties produced a mix of male and female plants. However, ways have now been found to effectively propagate all-male varieties of asparagus.  So look out for all male varieties such as the Jersey Series when buying your seeds or crowns.

    Timings

    Asparagus is a vegetable for the patient gardener.   It can be grown from seed or from mature crowns bought from a garden centre. The plant needs to establish a strong root system though so, if grown from seed, the shoots will not be ready for harvest for 3 or even 4 years.  Even if grown from a crown, the shoots should not be harvested until the year following planting.  In short, asparagus epitomises the saying "Good things come to those that wait"!

    Seeds

    IN GREENHOUSE/ WINDOWSILL:             February
    Depth: 1/2" (1cm)

    TRANSPLANT OUTDOORS:                       April to June

    Crowns

    SOW CROWNS DIRECTLY OUTDOORS:   April to June
    Depth: 6" (15cm)

    Both

    DISTANCE BETWEEN ROWS:                     30” (80cm)

    DISTANCE BETWEEN PLANTS:                  20” (50cm)

    HARVEST:                                                    May and June – (once plant is mature - see Timing above)

    Planting

    Asparagus does not like to have its feet “wet,” so be sure that your garden bed has excellent drainage.  Raised Beds are a great place to plant asparagus and mean a lot less digging.

    How to plant

    Firstly, clear the bed and make sure there are no weeds.  Then, work in a 2"-4" layer of compost, manure or soil improver.
    Prepare shallow trenches about 12" (30cm) wide and 6" (15cm) deep.  You might want to make these slightly deeper if you have sandy soil (8"/ 20cm) or slightly shallower if you have heavy soil (4"/ 10cm)
    Space the crowns 15" to 20" (38-50cm) apart in rows that are 30" (80cm) apart. Spread the roots out in the trench with the buds pointing upward.
    Lastly, once planted, completely fill in the trench with soil.  In your grandfather's day many people used to gradually fill the trenches with soil as the plants grew but no one seems to do this anymore.  When the trench is filled, add a 4-8" (10-20 cm) layer of mulch and water regularly.

    For the first year, just let the asparagus grow to give the crown a chance to get well established. If growing from seed then repeat this for the next 2 to 3 years! The following spring, remove the old fern growth from the previous year.  You should see new spears begin to emerge.

    Pests

    Though not a huge threat, the main threat to your asparagus is the Asparagus Beetle - read more about this in out Pests & Diseases: Asparagus Beetle Blog

    Harvesting

    Only harvest from established plants - see Timings above.  Allow the shoots to grow to roughly 6” (15cm) then cut it 2” (5cm) under the ground with a sharp knife.  This will give a partially blanched stem where the lower stem has had no light.  The French, who are great lovers of asparagus,  like to grow it under mounds, blanching them when the tops peek out.  They then cut them 10” (25cm) under the ground.  So if you prefer your asparagus white then this is an option.

    The spears grow quickly so leave it no longer than every other day to check for spears ready to harvest.  They will quickly become woody and inedible of you miss your window,

    Once an asparagus spear starts to open and have foliage, it’s too tough for eating. Stop harvesting spears when the diameter of the spears decreases to the size of a pencil. At that point, it’s time to let them grow and gain strength for next spring.  

    Immature plants will have a season of only 2 to 3 weeks. With proper care though this will extend to up to 8 weeks for established plants.

    When the harvest is over let the plants grow into fun leafy plants. Always leave at least one spear.  Keep the area around them weeded to keep the plants strong. Cut back the asparagus to about 2" (5cm) above the ground in autumn when the foliage has died back and turned yellowy, brown.

    Lastly, before cutting back, mark the bed well so that you don't accidently dig up your precious plants.  Otherwise your patient waiting will have been for nothing!

    Storing

    Asparagus does not last for long, best to eat the spears as fresh as possible. It has to be one of the main benefits of growing it yourself to pick it straight from the garden to eat the same day.  You can of course blanch them and then freeze them, but they are never as good.

    If you do need to store them then the best way, if you have enough space in your fridge, is to  treat them just like cut flowers and place the spears in a 2-3" of water.  Alternatively, bundle the spears together, wrap the stem ends of the spears in a moist paper towel, and place the bundle in a plastic bag. Store in the salad drawer of your refrigerator. 

    Eating

    Simple is best.  Lots of melted butter or a simple Hollandaise Sauce are perfect accompaniments.

    To see an asparagus bed being put together and get more hints and tips why not visit our YouTube channel and take a look at Madeleine's helpful video Growing Asparagus ?

  • Tips and Tricks: Seed Germination

    Germination

    Germination is the process by which an organism grows from a seed or similar structure and develops into a new plant. Three key environmental factors are important to trigger the seed to grow. We are going to call these the Germination Triangle and these factors are :

    • how how much water is available
    • the temperature
    • the planting depth of the seed

    A careful balance is needed between these three factors.  How dependent the seed is on them varies depending on the plant.  Some seeds will grow anywhere (and we wish they wouldn't!) whilst some need infuriatingly perfect conditions to germinate.

    Stagesseeds_in_bowls_pre_germination

    Water is key as the first stage is for the seed to fill with water in a process called imbibition. The water activates special proteins, called enzymes which that begin the process of seed growth.

    First the seed uses the carbohydrates and proteins stored inside to grows a root (radicle).  The root accesses water before the next stage begins: sending up a shoot above ground. As the shoot develops there will be secondary root formation and branching of the roots.

    By now the seed's reserves are running out so the next stage is to grow leaves to harvest energy from the sun. The leaves continue to grow towards the light source in a process called photomorphogenesis.

    etiolated_seedling_post_germination

     

    Light is very important at this stage.  If there isn't enough light this causes the plants to become etiolated. This is a natural adaptation to help the shoots elongate quickly to break through the soil and reach the light.  However, if it takes too long to reach light the resulting plants will not be strong.  The seedlings will become elongated, spindly, leafless and pale with a poor root system.

     

     

     

     

     


    The Germination Triangle

    Water

    The amount of water has to be just right for optimum growth.  Too little and the seed won't grow.  Too much and the seed will be unable to access the oxygen in the soil and won't develop.  It will basically drown.
    With careful watering, this balance is simple to achieve when you germinate your seeds in seed trays or pots.  If you are sowing direct outside preparing the soil ahead of planting will help you get the water balance right.  Ways you could do this include:-

    • Keep off the soil to prevent compacting - if you have to walk across it then lay long planks to use
    • Aerate the soil - if there are no air gaps then you can create them by aerating the soil with a garden fork or machines that do the job can be hired easily
    • Dig through a balanced fertiliser to break up and improve the soil
    • Use a Raised Bed - the easy way to do it but remember not to walk on it and compact the soil
    •  If your plot is very waterlogged adding a ditch or seasonal pond at the lowest part of the garden for excess water to soak away will be helpful.  This has the advantage of creating a habitat for slug eating frogs and toads which you can read more about in our Pests & Diseases - Slugs & snails blog.

    Temperature

    Temperature is also an important factor. The temperature a seed needs to germinate will often be determined by where the plant originates.  Those that come from Northern climates will often germinate at cooler temperatures than those native to the tropics.  Of course there are exceptions to any rule but many seeds will only germinate when the weather reaches spring temperatures. This can lead to confusion in plants when a freak warm spell causes them to germinate too early leaving them vulnerable to frosts which should be over.

    Some seeds only germinate after extreme temperatures, such as after a forest fire or an extended cold period but there aren't many of these plants in your average veg garden.

    The best way to judge soil temperature is to test with a metal thermometer.  Insert it 3 or 4 inches into the soil 3 or 4 days in a row.  The soil can be warmed by the sun later in the day so morning is the best time to test.  If the soil isn't warm enough then warming it with a Seedling Tunnel is a good option to allow you to start planting earlier than your neighbours.

    Charts are available online to tell you what temperature a particular plant may prefer.  From an optimum 40 degrees for a pea plant to 70 degrees for a tomato.  Once you feel the soil is warm enough, check the long range weather forecast for expected cold snaps and you should be safe to plant.  If the forecast fails you then methods such as or using Bell Cloches or Poly tunnels to shield young seedlings are foremost in the gardener's armoury to start successful germination.

    Planting Depth

    Planting at the right depth improves the seeds chances dramatically and will increase your germination success rate.  The seed will only store enough energy to sprout and reach the light so planting too deep may mean it does not have the energy to make it out of the ground.  If you plant it too shallow then it may fall prey to birds or dehydrate preventing germination.

    Generally the seed packet will clearly show the planting depth so is simple enough to achieve.  But what if a friend gave you the seeds, you harvested them yourself or just lost the packet?   You can look it up on the seed company's website or check out similar packets at your garden centre.  Or you could try and work it out yourself.

    To calculate it yourself, the word on the allotment is that seeds should be planted no deeper than two (or three - opinions vary!)  times their diameter.   This may differ from what's on the seed packet which too often seems to be 1/4 of an inch.  So experimenting planting some at the packet depth and some at the calculated depth might improve germination rates.

    Shallow planting

    Some seeds actually need light to germinate e.g. lettuce and dill.  These tend to be very tiny and should be placed on the surface of the soil and not covered.  The challenge with these is to keep them moist as they quickly dehydrate without a covering. If growing in seed trays  - cover with plastic to prevent the water evaporating away. Or cover with a fine layer of vermiculite - a soilless, mineral growing medium - which is porous and lets light shine through, while keeping enough water around the seeds so that they remain moist.

    Deep plantingRootrainers_with_seed_gemination

    Those that need to be planted deeper can benefit from Rootrainers where deeper cells can be chosen for plants that need the extra depth and moisture can be retained by using the integral cover.

    Position

    The final piece in the puzzle is where you plant them.  Some seedlings such as carrots do not like to be transplanted so it is important to sow these in the position you want them to grow.  Others can handle being moved so give you an opportunity to make the most of the short growing season by starting them off inside and transplanting them into growing position the minute growing conditions are right.

    table_of_veg_

    I hope that this has given you some tips to increase the germination success rate in your garden.  Given the delicacy of the balance that needs to be struck for healthy robust seedlings to germinate and grow you can only marvel at how the self seeders in your garden manage so easily what gardeners work so hard to achieve.

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