window screen would stop solids but not liquids.
could you post a picture of your system? generally the roots will grow wherever there is moisture(upstream or down) so it's possible your system has too much slope and is pulling them downstream.

Hi greendevelopment
>>I wonder how to establish boundary for root growth. ......Since root length follows plant length, when cucumber vine reaches out the root will too. Right, root length will follow plant length. That is the main reason why cucumber and other plants of that family are said to grow better in (actually belong into) soil culture.

Though, I am growing cucumber, pumpkins and others in hydroponics and am using long runs with single plants for that purpose. You can give them 2-3 meter (up to 6-9 feet) for root development. There is not much sens in using any kind of root boundary here. Instead trim (and train) plants AND roots. Btw: the roots may actually grow into the nutrient reservoir as long as they do not clog anything or prevent nutrient solution from running smootly. I have let some grow into the reservoir and have been triming them only from there. Hence in that case, the size of the outlet matters!

Cheers, Lucas

Thanks for your ideas. Sounds like it is not practical to consider root boundary for cucumber. How about other plants? In general how to setup root boundary?

Hi again,
Cucumber and other members of the cucurbitaceae family or (and of the genus cucurbita) are quite an exception. For most other plants, root boundaries are not used and generally not necessary as far as I know.

Too prevent excessive root length with some plants, you may trim the seedlings' roots to get more lateral roots. But in general root growth is not a major problem. As nutrients and water are always available for the plant, the root system tends to be less developed as in soil culture. With some plants and some setups, the frequency of irrigation and the concentration of the nutrient may have an impact on root size as well.

PS: In scientific research, nutrient composition is often tested for the best relation of sprout growth vs. root development. Hence, a specific composition of NPK of your nutrients is also a way to control or influence the relation between sprout- and root growth. In other words, the right nutrient will regulate- or may prevent excessive root growth. But this is rather a fine tuning for best yield, as a way of controling root length.

The way to control root length with hydro is with a pair of scissors.....prune the roots and top.

I didn't on chile no 1 and did with chile no 2 and plants grew equally as well.

I only have experience with peppers, but it sounds like cucumbers might do well in rockwool slabs. That's a different type of setup though...