Designing a garden is not just about space. It is also about time. This often-overlooked fourth dimension shapes everything from plant selection, spacing, and seasonal rhythms. A garden is a living system, and if you ignore time, you are setting yourself up for disappointment. In this Hot Plant Tip, we look at how time and phenology (the science of cyclic and seasonal natural phenomena) can help guide long-lasting, vibrant planting design, especially in a place like Southern California where rainfall is limited and seasonal cues are subtle.
Designing for Time
Gardens are living, ever-changing compositions. Unlike static architecture, a planted landscape transforms over time. Plants grow, spread, and sometimes decline, while the seasons alter the garden’s appearance. This is why time is considered the fourth dimension of garden design. There will always be change in the garden. A good planting design is not frozen in time, it is a dynamic, unfolding composition. There is a saying many gardeners know: “First year, sleep. Second year, creep. Third year, leap.” Understanding this timeline helps set realistic expectations, since a newly planted bed might look sparse or small at first, but given time, it can become lush and full. Expecting instant results is a recipe for disappointment. Explaining to your client early on that the best landscapes only get better with time is essential.
Spacing Plants with the Future in Mind
It is tempting to cram young plants together so a garden looks full on day one. But crowding leads to problems down the line: poor airflow, pests, disease, stunted growth, and excessive maintenance.
Everyone develops a different approach to solve this issue. You can space your plants according to mature size and use short-term fillers if you need visual coverage. Annuals like California poppy or Clarkia can fill the gaps in early years, then die back when dry season arrives, letting longer-lived shrubs take over. Or you can intentionally overplant and plan to edit later. This approach creates instant fullness but requires ongoing thinning. If you choose this route, make sure to tell your client, and put it in writing if you can. Explain that some plants will be removed in year two or three as others expand, or write it in a Maintenance Manual, since you likely will have moved on to the next project once its time to remove plants.
Gardens Need Editing Too
Some plants will surprise you, thriving in ways you did not expect. Others will disappoint. That is natural. Every garden needs editing. Think of yourself as a writer revising a draft. What is working? What is not? Do not be afraid to remove a plant if it no longer fits. Maybe your ornamental grasses dried out. A small shrub now casts deep shade on a neighbor. Maybe a plant grew bigger more quickly than you expected and is crowding out all your other plants.
Editing is not failure. It is part of long-term success. As landscape architects, we usually don't have the opportunity to oversee these adjustments, but they definitely happen without you. It's worthwhile to periodically visit your projects after completion and take notes. You will learn from what worked and what did not. Has the Carex disappeared entirely? Is a single Rhus now ten feet tall and swallowing its neighbors? Learning from these lessons informs your next design and it will make you a better designer.
Conditions Will Change
Even if you design everything perfectly, the site will change over the years. A sunny space becomes shady. A dry swale becomes wetter as trees grow and cast shade or drop organic matter. New structures will get built or trees will grow roots and crowd out plants. Good garden design accounts for these shifts. Think of the garden as an evolving ecosystem and plan for succession. Understand that the palette and layout may need to change over time, and talk to your clients about it. If you won’t be around to oversee this evolution, leave behind guidance. Include notes in your specs or maintenance manual about expected removals if you overplanted for day one effect, or replacement shade-loving plant recommendations for eventual canopy tree development. Future-proofing the garden vision increases its chance of success.
Phenology: Nature’s Calendar
Planting according to a fixed calendar date is a blunt tool. Nature operates with more nuance. Phenology is the science of seasonal biological events like flowering, leaf-out, or the appearance of pollinators. These events are shaped by temperature, rainfall, and daylight. Observing them tells you when the soil is ready, when pests may arrive, or when to prune. Phenological cues are more reliable than any calendar date.
In Southern California, we do not have snowmelt or frost to mark seasons. Instead, we track things like when wild mustard blooms on hillsides or when swallows return. If the Ceanothus is blooming, the native pollinators are likely active. If the jacarandas are in flower, summer heat is on its way. Keeping a personal garden journal of bloom times, bird sightings, or insect activity can help you sync your work to the natural world. Ultimately, your own eyes will be the most accurate. Your yard might be two weeks ahead of the next neighborhood over. Trust what you see. Over time, you can build a calendar based on your microclimate, not on national averages or what it says in a plant book or on the internet. Check out organizations like the USA National Phenology Network, which offer tools for tracking and comparing data across regions. If you start a habit of noticing what’s in bloom, what’s dying back, or what butterflies you see, you’ll change your way of thinking about the natural world we live in, and you won’t be able to switch it off. This is a good thing!
Timing Planting
One of the most important phenological events in Southern California is rain. Planting during the rainy season makes a huge difference on the long term health of our landscape projects. Typically rain falls between October and April, meaning soil is soft and receptive, and roots can establish themselves faster and with less irrigation. If you plant in summer, you will be watering daily in the hopes of keeping your plants alive, which is wasteful and leads to weaker plants in the long term. It is standard in our planting specifications to limit installation to this rainier window, but I’ve never had a contractor delay planting in favor of better climatic conditions – projects have to be completed when they need to be completed.
As designers, we should advocate for seasonal planting. Push back if someone tries to install a garden in the dry season just to meet a ribbon-cutting. It may survive, but it will not thrive. And it likely won’t deliver on the vision you designed. When you plant in sync with natural cycles, you give your design its best chance to succeed.
Conclusion: Let the Garden Grow
Designing with time in mind means you are not just planting for today. You are imagining what this space will look like in five years, in ten years, in twenty. You are building in flexibility, anticipating edits, and working with nature rather than against it. This approach creates gardens that do not just survive but evolve, deepen, and grow richer each season.
Phenology and time are tools for long-term thinking. They remind us that a successfully installed garden is not a finished product. It is just the beginning of a relationship that will deepen over time, shaped by change, care, and continued observation. Time is not the enemy of garden design. It is one of your strongest collaborators.
Watch for pollinators to arrive if their presence is necessary for the success of a plant. There’s a reason why we don’t plant tomatoes in January. The tomato blossoms need to be pollinated if the plant is going to produce fruit (tomatoes)! The bees that do most of the pollinating are not active until the night time temperatures are consistently 55 degrees. In Zone 24(coastal Southern California) that usually happens in early to mid-April. I have hand-pollinated tomato blossoms if the bees arrive late, but it’s a lot of work and the tomatoes that ripen a couple of weeks early aren’t always sweet. Timing really is everything!