Hi, Am a gardening newbie and am trying to grow a shrub variety tomato plant from seeds purchased at the local store. Seeds were planted three weeks ago and over the last week have been noticing burnt leaft tips. Seeds were planted in a potting mix and have not applied fertilizer yet. Summer is well underway in my region (40-50 deg celcius peak temp). Plant is in a open balcony behind a reflection coated glass barrier and facing west. It gets about 4 hrs of sunlight (2-6pm). Any suggestions on what is the cause or preventing this burn??
Outside United States
Thank you for contacting us. I can make several recommendations, however I cannot say exactly what is causing the burnt leaves.
Seeds are usually started in a soil-less mix to avoid potential fungal disease that often kills seedlings. Yours appear to be doing well with potting soil; however, the seedlings are much too close together. They should be pricked out and placed in separate containers so that the roots do not tangle together. Be sure there are drainage holes that allow any excess water to escape.
When seedlings are about 3 inches tall they should be fertilized with a half-strength solution of fish emulsion or a fertilizer made for vegetables. This can be repeated about every 10 days.
Tomatoes need at least 6 hours of full sunlight (or 14 hours when grown under florescent lights). Seedlings need to be watered frequently so they do not dry out completely.
Here is a fact sheet on growing tomatoes that may be helpful: http://www.gardening.cornell.edu/homegardening/sceneea10.html#growinginfo