Don't overlook the use of ground cover perennials to suppress weeds!
Weeds can become a problem in new and established herbaceous perennial borders. They are difficult to remove or control once they get a firm hold in your border, so, prevention is the key action to prevent a build-up of weeds in perennial beds and borders.
Regular hoeing between the perennial plants is always a good way to prevent a build-up of weeds, but take care not to damage any underground shoots of your perennials. If hoeing in the dormant season, it is easy to cut off the emerging shoots of your plants accidentally.
Once you have cleared the new weeds seedlings from your patch, and then apply a mulch – 2-3in deep – of compost, bark, or other organic material. Bark chippings are good and also look attractive.
When planting your perennial border, be sure to include a good selection of ground covering plants also.
Weeds such as docks and dandelions are deep rooted, and if you simply hoe the top off, they will re-sprout from the underground tap root. A sharp trowel is the best tool – or a small spade – to dig the roots right out. Try not to leave any root segments in the ground for they have the potential to re-grow into new weeds!
If the weeds are established in between your prized perennials, then a careful application of a suitable weed-gel – painted on the weeds leaves will be a good method of defence/offence! Make sure that you do not accidentally paint the leaves of your herbaceous perennials, for they will react the same way as the weeds – and die!
Weed gel normally contains Glyphosate weedkiller chemical. Glyphosate takes 10 days or so to work right through the treated weed and down into the roots, so be a patient.
Again, once your perennial bed is free of weeds, then mulch the ground between and up to your herbaceous perennials.