Written by Anna De Cordova, National Park Service Horticulturist
Coordinated by the F.W. Vanderbilt Garden Association
Photos by Sue Williams
The Rose Garden at the historic Vanderbilt Mansion in Hyde Park is the kind of ambitious display you expect to see at a billionaire’s estate: large, highly manicured, and artfully designed with lots of expensive hardscaping. The Vanderbilts used their home on the Hudson in the spring and fall, so roses were a natural choice for their gardens, which did not have to be at their peak in the heat of mid-summer. The Vanderbilt’s gardeners did not concern themselves as much with longevity of rose plants as we must on today’s budget and labor, and they routinely replaced rose plants to keep the display glorious.
Keeping gardens like this in shape in the modern era, without a billionaire and his staff requires a different sort of wealth – dedicated volunteers! The Frederick W. Vanderbilt Garden Association (FWVGA) is the treasure chest of people that supports the garden today. In recent years, the volunteers noted that the roses were showing signs of stress with less vigor and resistance than they had had in the past. The time had come to roll up their sleeves and improve the garden from the soil up.
Improving your soil sounds basic, but when you have a perennial crop like roses, the soil is not that easy to take care of because the plants are largely in the way for years and years. With the difficult decision to remove all the roses, came the great opportunity to give back to the foundation of the garden –its soil.
The first step was to have the garden soil analyzed for its pH and nutrient capacity, and the results of all the soil tests were very good. However, the soil structure – its ability to aggregate, its pore space for roots, water and air, and its organic matter content were all low. With roses in place for years, soluble fertilizer salts accumulated to the point that the soil structure was adversely affected. This is difficult to impossible to correct with the plants in place, but reversible once the plants were out of the way. As a first step, the gardeners tilled in manure which provides an injection of organic matter, nutrients and soil building micro-organisms. All gardens and gardeners love manure. There are lively debates about the preference of chicken vs. cow vs. horse manure but perfect consensus on one thing –all of these improve soil health. The National Park Service has a free source for horse manure not too far away, so that is what they added – complete with stall shavings, horse hair, bits of twine and the occasional hoof trimming. Yum!
Once the manure was incorporated into the soil, the action began. Invisible and visible soil organisms kicked into gear, processing the organic matter and releasing by-products that build soil structure. When the Lower Rose Garden was tilled a second time, a few weeks after the manure was incorporated, the worms were teeming in the soil where there had previously been no worm activity.
What next? With a whole growing season to continue to improve the garden, and impatient weeds bursting out all over, cover crops seemed the perfect solution to continuing to improve the garden soil. The gardeners sowed Buckwheat and Mustard in the symmetrical rose beds–adding nutrients and organic matter, improving soil structure deep below the surface, and suppressing weeds. Both crops are great soil conditioners. Buckwheat is very quick competition for weeds which was important in order to reduce labor. Mustard has anti-fungal properties that might be particularly beneficial to roses. Both crops grow extensive root systems that create pathways deep in the soil profile. Sowing two crops gave a nice contrast in the lower garden beds. One visitor commented, “I love it. It looks like a Mondrian painting!” The interest and enthusiasm of visitors was a relief given that it certainly wasn’t a rose display.
Cover crops come in a great variety. You can choose the crop that is right for your garden based on the soil type, the season you are growing in and the benefits you desire. Johnny’s Select Seeds has a good overview on cover crops and a handy chart you can use to compare various crops. Summer cover crops are quick. You sow the seed, grow the plant to any size you choose prior to seed formation, and then till the plants into the soil. The FWVGA allowed their crops to grow until flowering, so they mowed them down and dried the plants out for a few days to make tilling in easier. Then they re-sowed the crop. When a cover crop is incorporated into the soil, it releases sugar and nitrogen that set off a frenzy of invisible microbial activity. In addition, fungi break down the plant cellulose into humus, and worms, ants and other visible critters take care of the bigger mouthfuls.
You can use cover crops in any season, even over winter, and even in small patches of garden that need improving before re-planting. They are terrific in home vegetable gardens when crops can’t be rotated or a crop, like squash or cucumber, has died off before the growing season ends. Many vegetable seed catalogs carry them and they can be purchased from local farm supply stores.
This winter the Vanderbilt Garden rose beds are covered in summer alfalfa, a crop that fixes nitrogen and dies off naturally in winter. A light cover of autumn leaves went down on top of that, and everything will be tilled again in early spring before the first roses are planted. The new roses, selected for their vigor and their relevance to the historic plantings, will be moving into luxurious accommodations – soil perfectly suited to the lifestyle of a Gilded Age plant.
Get involved with the Vanderbilt Garden
The Frederick W. Vanderbilt Garden Association is a non-profit organization dedicated to the rehabilitation and continuing beauty of the formal gardens of the F. W. Vanderbilt National Historic Site in Hyde Park, NY. Volunteers meet in the gardens Tuesday, Thursday and Saturday mornings from April – October. Members must volunteer 15 hours per year. In addition to gardening, volunteers are also needed to work on various committees, on fundraising, researching grants, or serving on our Board of Directors.
For more information call (845)229-6432 , leave your name & phone number and someone will get back to you. Visit the FWVGA website for more info about volunteering, guided tours and upcoming events.