Water Melilotus altissimus regularly during its establishment phase, ensuring the soil remains consistently moist but not waterlogged.

Once established, it becomes drought-tolerant and requires infrequent watering, especially in cooler climates. Overwatering can lead to root rot.

Pruning is typically not necessary for Melilotus altissimus unless it is being used as a cover crop or needs to be managed for size.

If desired, it can be cut back after flowering to prevent excessive seed set or to encourage a tidier appearance. For cover cropping, it's often tilled under.

Melilotus altissimus is easily propagated by seed. Sow seeds directly outdoors in early spring or autumn.

Scarification or pre-soaking the seeds can improve germination rates, as the hard seed coat can inhibit water uptake. It can also self-seed readily.

Repotting is not applicable to Melilotus altissimus, as it is a herbaceous perennial or biennial typically grown from seed directly in the ground or as a cover crop. It is not usually cultivated in containers where repotting would be a consideration.