When buying asparagus plants for a newly created asparagus bed, most plant retailers will only offer a small range of one or two year old plants. Although they will always look healthy in the pots, there is always a risk of failure when it comes to transplanting - around 10%-15% for one year old stock and as high as 20% for 2 year old stock. When paying full retail prices - particularly with regards to 2 year old stock - this can end up being an expensive lesson.
In addition, with direct sowing there is no transplanting or root shock to delay valuable root development.
The best time to sow asparagus seeds is around mid-April when the ground is warm enough to initiate germination. A good tip is to soak the seeds in water for a couple of hours before planting.
You will find that this will help to speed up the germination process considerably.
The new seedlings should emerge in about 3 weeks, and as soon as they are large enough they can be thinned out to about 2in apart. Then, once the seedlings reach about 6 inches high, they can be thinned out again to around 18 inches apart. For the rest of the year you just need to keep the beds weeded and the plants well-watered.
If you have bought seed varieties that produce both male and female plants, you will need to remove any female forms as soon as they become identifiable - normally from their berries.
Once the threat of frosts are over they will need to be gradually accustomed to conditions outside - this known as 'hardening off' and can take between 2-3 weeks. Once they are ready to be moved out into the asparagus bed proper, they can to be planted fairly deeply leaving a couple of inches of soil above the level of the compost. Keep them nicely watered over the summer period and - as always - keep the bed free of weeds, especially perennial weeds which will compete with your seedlings roots for nutrients.
Growing your own plants can delay establishment of your bed by an additional year, but it does ensure that you are starting with new crowns that have not lost none of their vigour through being lifted, stored and shipped. However, not only will you have a larger selection of varieties available to you, if you choose your varieties wisely you will still be able to harvest in their second year.