let asparagus rest after harvest

Once you finish your harvest, leave your asparagus alone so it can recharge. Traditionally the growing season ends on June 24th (St. John's Day), and those who observe this date give the plants the necessary time to regenerate. From that point onwards, the fine, feathery green shoots serve as a "photosynthesis factory," collecting energy and storing it in the rootstock in the form of carbohydrates. This phase is important for building up reserves for the next harvest year. If you allow the plant this regeneration time, it can be harvested repeatedly for decades. In the first two years, you should only harvest a small amount over a period of two weeks. In the third year, you can extend the harvest period by one week per growing season, harvesting for three weeks, and in the fourth year expand to four weeks. End the harvest time at the latest when the spears become significantly thinner. The asparagus foliage must not be cut after harvest, as it is essential for directing energy into the roots in the form of carbohydrates.

When you walk over your garden bed in summer, you see the foliage standing before you like a factory of green leaves. These plants use sunlight to produce carbohydrates and direct them straight into the rhizome. The foliage absorbs nutrients during the long growing season that are important for building up reserves. You should not cut back the foliage prematurely in summer, as you would interrupt the energy transfer to the rhizome and thus reduce next year's yields. Pruning is only necessary if stems are actively affected by diseases such as asparagus rust or rot. Thinner shoots can be left standing in summer; they grow into stronger fern plants. If the tall perennials in your garden beds might fall apart or break, a taut string helps as support. The remaining shoots can reach up to 1.50 meters high and even two meters in summer while forming flowers. Female plants develop red berries through pollination that can cause stomach aches — caution is therefore advised during harvest. Since berry development costs a lot of energy, male plants are mostly preferred for cultivation.

As soon as you have completed your last harvest, your asparagus field needs targeted support so that it can gather strength for the next year. The plants use the time after cutting to gain energy through photosynthesis and store this as reserve material in the roots. To support this buildup of supplies, a moderate supply of nitrogen as well as sufficient potassium is important. Immediately after the end of harvest — usually in June or July — you should help with organic solid fertilizer such as horn meal (approx. 80–100 g/m²) or compost (3–5 liters per square meter, worked in shallowly) to ensure nutrient supply for leaf growth. If necessary, a further light nitrogen application of maximum 40–50 g/m² can be made from mid to late July. An excess of nitrogen often shows itself through excessively soft, dark foliage that is very susceptible to fungal diseases such as asparagus rust. For established crops, fertilization with phosphorus-rich products like bone meal or a potassium-rich mixture makes sense after the last harvest, as this promotes foliage growth and stores nutrients for next year's spears in the root crown. From mid-August onwards, the focus shifts to potassium to support nutrient transport into the roots and improve frost resistance.

If the foliage yellows and dies off on its own between October and December, you should cut it back close to the ground. As long as the heads are still closed, green shoots will be cut directly above the soil; if you leave the foliage standing, fewer or no new shoots will grow. Anyone who cuts away the foliage in September for aesthetic reasons halves the reserves for the next growing season. For brown and dry shoots, pruning of withered foliage takes place in late autumn with sharp garden shears to avoid long stumps that could serve as shelter for pests. You have two options: either leave the dead foliage standing over winter and cut it back only in spring before new growth appears, or cut it directly at ground level and distribute the brittle stalks as a winter layer over the asparagus bed. A layer of soil and mulch serves as natural frost protection for the upper root zone of the asparagus rows. If pest infestation occurred during the growing season, you should remove the foliage before winter and dispose of it in bags rather than putting it on the compost, as many home compost piles are not hot enough to destroy eggs and pathogens. A layer of compost protects the soil from frost and controls nutrient release for spring.

Between June and October, the plant fills its storage roots with sugar and starch to prepare for spring growth. If these reserves are missing, the stalks remain thin and the harvest meager. You can support this soil building by growing deep-rooting soybeans, lupins or bush beans; they leave behind well-aerated, humus-rich and loose soil in which green asparagus can quickly take root. A green manure with yellow mustard or oil radish also helps you to loosen the soil through the root system and improve aeration as well as water conductivity.