Bulb Research


In the spring of 2014, we noted a steady decline in tulip condition and performance in several of our bulb beds on Great Hill. The main culprits were animal, specifically rodents such as voles and chipmunks as well as fungal, with a frequent occurrence of botrytis blight or “tulip fire.” In attempts to ward off the rodents, we utilized several cultural methods such as, planting a row of allium amongst the tulips when possible to act as a deterrent, as well as planting the bulbs with red pepper flakes and or cayenne pepper. We also applied natural repellents such as Bobbex and Plant Skydd to beds in the fall and spring post planting. Both of these chemicals are mixtures of various animal repelling substances such as garlic, fish and clove oil etc. We found that over time, animals became used to the bobbex, and not the plant skydd, making it much more effective in long term application. Lastly, when possible, we used structural barriers on our beds. Applying mesh netting over bulb beds, however, proved ineffective as its short term and digging rodents easily bypassed these barriers.

Incorporation of other bulbs

The 2015 and 2016 bulb seasons were disappointing. At this point we were also applying seasonal chemical applications to our bulb beds in order to control fungal issues. During the 2016 season it was recommended to us by our licensed chemical applicator to begin to either use less tulips, or omit tulips all together in some of these beds to give the soil a chance to recover from frequent, long lasting, fungal infection. As removing the tulips completely was not an option we were approved to work with, we started researching the incorporation of other bulbs, mainly daffodils. While we routinely used hyacinth, muscari, allium and others the animals don’t eat, we hadn’t ever mixed daffodils with our tulips in large numbers.

In beds where we had used 100% tulips in the past, we started planting about 25% tulips, 50% daffodils and 25% misc. other bulbs. Our switch could not have happened at a better time. During the 2016 season the bulb catalogs were filled with a variety of new daffodil hybrids bringing much more to the color palate than the traditional buttercup yellow narcissi of the past. New daffodils came in a variety of heights, ranged in color from white to orange and pink to many softer shades of yellow. There were now small cupped, split cupped, extra-large cupped and even doubles. The best part about our incorporation of daffodil hybrids (while their performance was outstanding) was that it kept our animal and fungal issues to a bare and manageable minimum. The 2017 bulb season was a huge success. Consequently, in doing our most recent bulb order, we’ve continued to heavily utilize daffodils as well as many other rodent and disease resistant bulbs such as anemone, camassia and new allium hybrids. We plan on continuing to update our bulb research information as our trials progress.

Grit/Crushed Stone

In the spring of 2019, several different daffodil mixtures we had planted were blooming in the three major driveway/entrance beds to Great Hill. These mixes included daffodil ranging in heights from 10 to 24” inches, varieties of single, double, split cup, trumpet and double blooms, and colors ranging from dark to light yellow, white, pink, orange and coral. While they bloomed beautifully, we found the effect, overall, a naturalizing one in an area that’s meant to stand out and catch the eye. As such, we decided we needed to attempt and once again incorporate tulips into these beds. In order to do this successfully, we’d have the huge task of attempting to outsmart a variety of rodents such as voles, chipmunks, squirrels and gophers.

In the fall of 2020, we purchased several bags of turkey grit, brought up loads of unused, inexpensive crushed stone from our nursery stock, and purchased tubs of garlic and cayenne powder, and red pepper flakes. In the three driveway beds, along with a couple other bulb beds on the property with a lot of underground rodent activity, we decided to layer a mixture of the grit and or stone with a mix of spices both under and over our bulbs when planting, in order to act as a deterrent and protect our bulbs and their roots from being eaten. In these beds, we dug out a trench to meet the planting depth of our largest bulbs, shoveled in a solid 1-2” layer of stone and grit and topped the grit with a layer of a mix of the three spices. We then laid out our bulbs and added another grit and spices layer, and finally, covered the trench with dirt. In beds where we were mixing both large and small bulbs, we would dig a trench deep enough for our largest bulbs, add a layer of grit and spices and dirt, and then incorporate the smaller bulbs in the bed to meet their required depth, often repeating this a couple of times. For example, in the same beds, we might be planting daffodils, tulips and muscari, all of which require different planting depths.
While we realize that the ground spices might not have had the longest shelf life in the ground, we’re hoping it helped to deter rodents during the late fall when they were starting to establish underground winter tunnels. Once the bulbs start to emerge, we plan on regularly spraying beds with a number of deterrents to keep our digging, above ground rodents at bay. We will add updates to this research as our spring bulb season materializes.

Hardware Cloth

The results of the 2020 planting incorporating grit and crushed stone were mixed. In beds where vole activity is scarce or limited, the grit proved to greatly deter. In the areas where there are higher populations however, the grit was minimally effective. Adding to this, we realized that amending the beds with literal yards of crushed stone and grit each season was not only labor intensive, but impractical. Having had our first small taste of tulip success in many seasons, we decided to get serious about deterrent in the fall of 2021.

In our three main driveway bulb beds, we dug trenches large enough in width to fit our display (roughly 24-30”) and roughly 8” deep in order to accommodate the largest daffodil in the planned bulb mix. In the pre dug tranches,  we laid ½” hardware cloth to fill the depth and width, being sure we had enough cloth to cover the sides of the trenches in order to keep the entire planting protected. We held the cloth down with landscape staples and a thin layer of soil. To this preparation we directly planted our bulbs adding soil to meet required bulb depth where necessary.

The 2022 spring bulb display in our main driveway beds was as full and diverse as ever. We lost only a small handful of tulips at one of the furthest corner beds where small holes in the fencing were manipulated. In planting for the spring of 2023, we dug and amended these holes, finding the infrastructure of the cloth widely intact and in great shape.