My husband and I started an asparagus patch two springs ago and this year we have begun to enjoy having enough fresh asparagus spears for the table. It grows very well here in Central Texas and actually likes the soil to be slightly alkaline! Asparagus is one vegetable that is a long-lived perennial. If well maintained, an asparagus patch can be inherited by your great grandchildren as it can live for more than 50 years.
For the uninitiated, asparagus is a spring crop only. That's when you cut out the largest spears and allow those the diameter of a pencil to grow into tall ferns. This means that for about six weeks you can have all the fresh asparagus you want if you have planted enough. It is recommended that you snap off the biggest spears instead of cutting them to avoid damaging the crowns. You can also snap off the taller spears and they will break where the spear gets tough. Asparagus spears can grow four inches a day in warm weather! Five crowns of the newer hybrids for each family member is the recommended quantity. You must quit harvesting when most of the spears coming up are the size of a pencil. If you over harvest you will weaken the crowns and it can ruin your asparagus bed for the coming spring. The nice thing about asparagus is that it lasts very well if it is immediately refrigerated after harvesting, and you can collect enough spears over a week's time to feed your family. Freshly harvested asparagus that is quickly chilled is a treat because, like freshly harvested corn, it is full of sugars. These fruit sugars can turn to starch, and also get tough and stringy, if it is allowed to sit around unrefrigerated too long at farmer's markets or the local grocery store.
The recommended rust resistant varieties for Central Texas are Mary Washington, Jersey Knight and Jersey Giant. Asparagus can be easily started from seed, but will take several years longer before you can harvest any. You can find seed catalogs online which sell it. The seed takes a while to break dormancy, so it is best if they are soaked for up to a week before planting them. Change the soaking water daily, and when the week is up, dry them, and dust them with a fungicide, as Fusarium oxysporum f. asparagi, a Fusarium wilt disease, can have contaminated the seeds. It's better to be safe than sorry, because Fusarium wilt can live on in the soil for years and ruin your new asparagus bed. The seeds sprout best in soil temperatures of 77F, so they like to sprout in warmer weather. Keep the soil watered when dry, and they should sprout in about ten to twenty days. The advantage to growing asparagus from seed is that it is not only economical, but also you can weed out the female seed producing plants and only save the male plants. The male plants waste no energy producing seeds and therefore are the most productive ones. The female plants produce a lot of seeds which can also be spread by birds and wind and become a weed in themselves which are very hardy, resistant to herbicides, and impossible to pull up. You can buy all male plants from nurseries but they are more expensive. You can also choose only the biggest and healthiest ones for your garden if you grow your own crowns.
If you buy crowns from a nursery up north don't be surprised if some have already rotted by the time you get them. The crowns don't like to stay very wet, and if the weather turns hot before you get them, they can rot during shipping. It is best if you buy the crowns locally or from a California nursery for this reason. The best time to plant asparagus crowns in Texas is during the winter and early spring before they break dormancy and begin to come up. Plant them in a well-prepared fertile bed with deep topsoil. Make furrows six inches deep, six feet apart, and space the crowns in the furrows about a foot apart. Plant the crowns with about two inches of dirt above them, and fill in the furrows as they grow. Asparagus ferns grow tall and you will need to walk amongst them to cultivate them.
You can also make raised beds not wider than you can reach to the middle, and plant the whole bed with plants a foot apart. They like good drainage, for a wet spot will encourage Fusarium wilt and crown rot diseases. Don't make your bed where old asparagus grew in the past six years to avoid Fusarium wilt diseases. Keep them watered if the weather is dry, and don't give up, as it will take many weeks before they begin to sprout. Keep the bed weeded, mulched, and when the fronds get full size they will be about 4-5 foot tall and will shade themselves which will help to keep out weeds. Fertilize the bed moderately before the spears emerge, and again after harvesting. Asparagus are not heavy feeders of nitrogen. Blackland prairie soils have sufficient phosphate and potassium. If you have acidic sandy soil you'll have to water the beds more often and consequently also use more fertilizer. Watch out of rust during humid wet warm weather. If you see it, spray the fronds with a fungicide every seven days to maintain control or it can quickly take over turning the whole bed brown.
Destroy wild asparagus seedlings as they can become hosts. Also watch out for asparagus beetles and asparagus aphids. Control these insects with insecticide sprays. Organic sprays like pyrethrins are available. on the market. Be diligent when these appear because they also spread serious diseases like 'Witches' broom and Fusarium wilt. Maintain your asparagus bed and it will outlast you.