This section is from the book "The Gardener V1", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
This vegetable requires a light, deep, well-enriched soil to grow it well. In cold or northern districts - more especially if the soil be very heavy - it is apt to rot off in winter, and therefore is not adapted for growing in such situations. But most owners of gardens desire a little Asparagus; and for those who may be in a reasonably favourable situation for its production, I offer the following remarks:-
If the soil be heavy, some means must be taken to lighten it by mixing the staple with sandy soil, or replacing it altogether to the depth of 18 inches at the very least; and if 3 feet, so much the better. Of course the ground must be well drained. To prepare it, it must be trenched, and have a very liberal addition of manure in autumn. During dry or frosty weather, re-trench it for the purpose of thoroughly incorporating the manure. In April, mark the ground off into beds 5 feet wide, with 2-feet alleys between them. If the plants are to be raised from seed, sow it thinly in rows 18 inches apart; when the plants come up, thin them the first season to 3 inches apart, taking out every second plant the following year. Between these rows Spinach, Turnip, Onion, Lettuce, and other dwarf crops may be grown the first two years, as the Asparagus will not, until then, occupy the ground fully, and crops such as these will do no harm. If preferred, the seed may be sown on a small bed, and afterwards transplanted on permanent beds prepared as has been described. Unless very well grown they may stand in the seed-bed for two years, as Asparagus is about four years, under ordinary cultivation, in coming to perfection; and two-year-old plants are generally good for planting.
If sown where they are to remain, they will not receive the check which transplanting gives; but many prefer growing them in seed-beds at about 5 inches square until they are ready to transplant, and then they have the beds freshly prepared when they are planted. When the grass dies down at the approach of winter, cut it carefully over, and cover the beds with 2 or 3 inches of rotten dung. But amateurs may purchase their plants and transplant them in beds as described, and thus save the weariness of waiting for returns. The best time to plant is in April, in cold, late districts; and in March, in dry, warm ones, and just as they are beginning to move. If home raised, lift the plants with a fork very carefully, a few at a time, and plant them before they are much exposed to the air; if bought, leave them as little exposed to the weather as possible. The best way of planting is to stretch the line where the rows are to be, and beat the ground on both sides (as is done when Box edgings are laid), and then cut a trench 6 inches deep along one side of it, and put the plants in with their fibres spread out, and covered with well pulverised soil, keeping the crowns 2 inches or so below the surface. When finished, give a good watering if the weather be dry, and mulch slightly with rotten dung.
If the garden be exposed, it may be necessary to put in stakes, at distances of 4 feet, along each row, and stretch on them three rows of string, to which each stalk should be secured, as the wind may twist them over by the neck, and so destroy the plants. Mulch in winter as before directed.
Do not cut until the stem be coming up as thick as one's little finger; if they never grow that size they are a comparative failure. When they are that size, as they should be in two or three seasons at most, be careful to cut above the crown, and not destroy the rising buds. If not very strong, do not cut later than the end of May, otherwise they will be so much weakened as to prevent them fully recovering lost ground during the summer. If very strong, the cutting may go on until the 1st of June - not later. Afterwards encourage all possible growth so as to lay up a store for another year. In very suitable soils beds last many years when properly treated; in unfavourable soils they soon wear out, and must be renewed accordingly.
It is not likely that many villa-gardeners will practise this. The best method in small gardens is by means of a hot-bed; in large well-appointed ones, pits heated by hot-water are used. The best hot-bed for the purpose is one composed of half stable-yard manure and half leaves gathered off the lawns, etc, and kept dry for the purpose. These should be thrown together - well shaken out - and get a little sprinkling of water if too dry, and turned twice, at intervals of a week, or when it has fairly heated each time. It is then built up perfectly square a foot wider than the frame which is to be put on it, and firmly beaten down with the fork as the building proceeds. While building, keep it all equally level, and do not build one side before the other. When 3 feet high, put on your frame, and build your hot-bed material up to the top of the woodwork all round, then put on your light or lights, and wait for a day or two until the heat rises. If too dry, or if there be too great a proportion of fresh stable-yard manure, it will heat too violently.
But if the leaves were a little decayed, and the stable-yard manure not too fresh with the preparation described, it ought to rise gradually to 80° or 90° in the middle of the bed; and if there be no signs of it going higher, then get in the Asparagus roots with all possible speed. They can be bought, or you can rear them, but they will require to be four years old from the seed and fairly well grown before they are ready to force. They should be protected in their beds from frost, so that they can be lifted easily at any time. Lift carefully with a fork, and after putting 3 inches of friable soil on the bed, begin by putting the plants upright and quite close together; and when a sufficient quantity is in, fill in between the plants with fine dryish soil up to the crowns, and give a watering of tepid water to wash all interstices full, and over all put 2 inches of the same description of soil.
If succession crops be wanted from the same frame, divide the frame into the necessary divisions with boards, and fill each division at intervals of a week; and if necessary a second frame can be prepared in the same way. I have been thus particular because such a bed as I have described forms the very best appliance whereby to force Seakale and Rhubarb during winter, and is just the thing for Cucumber and Melon in summer, so I will not require to give directions for forming beds when treating of those subjects. There is this difference between Seakale and Rhubarb and Asparagus: the first two require to be kept in total darkness to secure the best results, but Asparagus is decidedly inferior when thus forced. To have it in full perfection both light and air are needful, so a glass frame is necessary; whereas any kind of frame, even hoops and mats, will do for Seakale and Rhubarb. The temperature for each and all of these requires to be between 50° and 60°, above that, they will be drawn and flavourless; and should the temperature go below that by reason of severe weather or a declining heat in the bed, mats or straw will be necessary to protect both frame and bed: and linings ought to be applied.
By linings I mean that a foot of material all round the frame should be removed, and two feet of hot manure put in its place. A cold frame put over a bed will forward it in the open ground a week or two.
As surely as the seasons revolve in their annual rotation, we have brought under our notice various observations about how best to grow Asparagus, and whether it really is a plant that sends its roots deeply into the soil. Some say it is a very deep-rooting plant, consequently requiring a deep soil in order to produce the best crops. Having seen very different ways of preparing the soil for this esteemed vegetable, and results equally different, I will not here detail these various methods, but simply make a few remarks founded on my own experience and observation.
I have seen acres of Asparagus raised from seed sown on a free loamy soil that had been previously well manured with stable-manure. If May and June prove moist, the plants get a good start, and make splendid plants the first season. As to their rooting deeply, I have, on the other hand, observed that three-fourths of the roots run nearly horizontally from the stems, and only about a fourth of them go directly downwards; and by the end of the first season's growth the horizontal roots were found in whorls from 18 inches to 2 feet long, the majority of the plants having formed several crowns ready to start into growth the following season.
In preparing the permanent beds, it is not necessary to raise them more than 6 inches above the ordinary level. The depth of artificial soil that it may be found necessary to add depends entirely on the nature of the soil, and more especially the subsoil. If it be clayey and retentive, drainage is of the first importance, and must be efficiently performed, or Asparagus will not last long in good condition on it. If the soil be poor, shallow, and gravelly, it is necessary to success that the staple be deepened with light loamy soil and manure, or the crops will be poor indeed. Anything like good crops need not be looked for unless the staple be at least 18 inches deep; and if it consists of good loamy soil, and about a fourth of the whole of well-rotted manure, all the better. The whole should be thoroughly well mixed, and placed in the beds a few months before planting-time, so that it subsides gradually. Some plant in single rows, others in beds; and, all other things being equal, there is not much difference in the result. I have seen excellent Asparagus grown in 5-feet beds, having 18-inch paths between. In these beds six lines of plants were planted.
Instead of laying the roots on the surface, and covering with the soil out of the paths, or artificial soil, I prefer making a little trench for each line, and letting the roots in rather deeply; for if a dry time occurs after planting, they are not so likely to suffer from drought, and the plants sown throw out fresh roots nearer the surface. If a mulching of manure can be laid on the surface of the bed, it is a great help to the young plants; but if this cannot be afforded, short grass will act as a conservative of moisture. When they have just begun to push their buds is the best time to plant, and this is generally in April. Throughout the summer a good soaking of liquid manure at intervals will greatly assist them; and if all goes well, they will make strong growth and mature good crowns that will the following year produce strong grass which, the third year, will be fit to cut freely for use. The main points of culture in after years consist in preventing the tops from being damaged by high winds, and in giving liberal top-dressings of rich manure, and keeping the beds quite free from weeds.