Heavy metal contamination has become a serious environmental problem. The effects of 0, 30 and 60 mgL^-1 Cu in the irrigation water and, 0, 2 and 4 mgL^-1 sea algal extract (Ascophyllum nodosum) foliar applications on the growth and some physiological characteristics of Lepidium sativum were studied. The experiment was factorial based on RCBD. Malondialdehyde content was affected by 60 mgL^-1 Cu treatment. Plant dry weight, total phenolic content and proline, Cu²⁺, K⁺, Mg²⁺, Fe²⁺ contents as well as catalase and peroxidase activity were influenced by the interaction effects of Cu treatment and foliar application of A. nodosum. For proline content, Cu _control × 2 and 4 mgL^-1 foliar application of algal extract was the treatment of choice. The lowest amount of total phenolics content was recorded with control plants. Peroxidase and Cu²⁺ content hold the top quantities at Cu of 60 mgL^-1 × non foliar applications. Plant dry weight had the highest data for Cu _control × 2 mgL^-1 foliar application and Cu of 30 mgL^-1 × 2 mgL^-1 algal foliar application. The data clearly shows that algal extract; due to the abundance of some nutritional elements reduces the toxic effects of Cu metals on plants.