Perennials need their space
It may not be the first thing that comes to mind when you think about perennial production, but spacing is just as important as water management, fertilizing, and disease control. It’s one of those preventative measures that you need to account for ahead of time or you’ll regret it. Space can be difficult to come by when you are trying to maximize the use of a limited area, but if you don’t space the varieties that need it in time, you will end up taking them out of inventory for weeks when they inevitably become unsaleable.
We space our #1 black pots simply by using extra trays and removing three of the six pots from each tray and arranging them in opposite triangular patterns so that each pot has an empty hole on each side of it. It can be difficult in the spring to find time to space plants, especially when some varieties can put on a lot of growth very quickly under the plastic of the polyhouses. This spring, our overwintered Delphiniums and Biokovo Geraniums shot up so fast that they were full in the pot by early April. Fortunately, though, we are usually able to move much of our spring inventory before it needs to be spaced. But by the time we get into late May and June, we need to have a real plan in place for where we will be able to space a lot of our inventory.
Spacing early is crucial for keeping certain varieties saleable; May Night Salvia, most Geraniums, Achillea, most Sedum, Liatris, Delphinium, Athyrium, Matteuccia, Monarda, Rudbeckia, and Lavandula are just a few of the varieties that we try to space as soon as they get full enough in the pot to start touching their neighbors. If you don’t space things like Monarda, Liatris, and Sedum in time, you will end up with plants that look great in the six-pack tray, but flop over and can’t support themselves on their own as soon as you remove one. Once you get to this point, you have no choice but to cut them back and wait for them to grow back. (I have learned this the hard way.) Lavandula ‘Munstead’ is very prone to foliar diseases, so spacing helps to give it the air circulation it needs to help prevent leaf spot.
While spacing Karl Foerster Calamagrostis and Walker’s Low Nepeta would be beneficial, we grow so many of these varieties that we simply don’t have the space or the labor. Spacing the Karl Foersters would have the cultural benefit of increased air circulation, which is helpful for such a rust-prone plant. But since we are limited by space and time, we try to control disease with the use of preventative fungicide instead. Nepeta can be notoriously difficult to keep under control, especially ‘Blue Wonder’ and ‘Walker’s Low’. They grow so fast that we generally can’t sell them before they start to stretch vertically and flop over. We try to manage this by planting multiple successive crops, and by cutting back a portion of the crop almost immediately once it starts to fill out. We also space our Hostas and Astilbe; while some of them would probably look ok without taking this extra step, giving them that extra space helps them fill out more uniformly.
We have found that it’s better to be safe than sorry when it comes to spacing; you are never going to hurt a plant by giving it that extra space, but you may regret it if you don’t. Spacing is an important part of an integrated approach to disease management, and it is absolutely necessary for the proper growth of certain plants. The biggest challenge for us is making the time and finding the space, especially in a heavy production year like this. When we are busy planting and making room for more plantings, it’s important to remember to pause and prioritize, and make time to space those critical varieties to keep them saleable for the future.
