I know it seems difficult to explain vocabulary to low levels without using their own language, so I understand your concerns. However, it is possible and when students (and teachers) get used to this approach they will progress much more quickly because they'll be in an all-English environment in the classroom.
There are many ways of explaining vocab without a translation. You can give the opposite of an adjective; for example happy and sad, hot and cold. This is good for abstract concepts. For verbs, especially action verbs you can mime the meaning. Many experienced teachers find themselves miming verbs without consciously thinking about it. Mime can also be used to portray adjectives describing feelings.
If the word represents a category, you can give examples of that category. For example, furniture: you list chair, table, sofa, etc. Choose examples that are typical to the category. So for vegetables, marrow and pumpkin are not the best examples. Another way to teach vocab is to show a picture. This is especially good for concrete nouns. If you know you are going to teach a lexical item, you can take the picture in with you. If not, and the word is taught because it comes up in the lesson, you can draw a picture on the board. You don't need to be a professional artist to do this. Pictures of stick men will do the job. There is also a book by Andrew Wright called "1000 Pictures for Teachers to Copy". This will give you tips on drawing and as the title says, pictures for you to copy. Finally, another way to teach vocab is to take the real items (realia) into the classroom. What better way is there to teach the word necklace?!!
At first, this might seem very long and laborious, but please persevere and you will see the results.