Why Won't My Asparagus Seeds Germinate?

Asparagus can be grown from seed, but it is one of the slower-germinating vegetables and requires specific conditions to succeed. Sowing asparagus seeds and seeing nothing happen for three to four weeks — or longer — is common and often perfectly normal. However, there are several conditions that cause complete germination failure, and knowing the difference between slow germination and no germination helps you decide whether to wait or to re-sow.

Asparagus needs warmth to germinate

Asparagus seeds need a soil temperature of at least 16°C to germinate, and germination is most reliable and quickest between 20–25°C. Seeds sown in cold compost in early spring — even on a windowsill — may sit for weeks or fail entirely if the temperature is too low. Using a heated propagator or a warm spot (such as on top of a boiler) to maintain warmth is highly beneficial. At the correct temperature, asparagus seeds germinate in two to three weeks. At lower temperatures, they may take six weeks or more, and below 10°C germination fails.

Old or dried-out seeds

Asparagus seeds have a relatively short viable life compared to many vegetables. Seeds more than two to three years old may have significantly reduced germination rates, particularly if they have been stored in warm, damp or fluctuating conditions. If you are using old seed saved from the garden, or an old packet, this is a likely cause of failure. Always sow fresh seed from a reliable supplier and store any unused seed in a cool, dry, dark place in a sealed container.

Soaking seeds before sowing

Asparagus seeds have a hard coat that slows water uptake. Soaking the seeds in warm water for 24–48 hours before sowing softens the seed coat and can significantly improve germination speed and rate. After soaking, sow immediately rather than letting soaked seeds dry out. This step is not strictly necessary but makes a noticeable difference in practice, particularly for seeds that are a year or two old.

Sowing depth and watering

Asparagus seeds should be sown about 2.5 cm (1 inch) deep in good-quality seed compost. Too shallow and the seeds dry out; too deep and they struggle to push through. The compost should be consistently moist but not waterlogged — overwatering causes the seeds to rot before germinating. A light covering of vermiculite helps retain moisture while allowing air exchange. Keep the compost moist and the tray warm until shoots appear.