The Best Time To Divide Hostas For Fuller, Healthier Plants

Hostas (Hosta spp.) are well-loved garden plants, known for their broad leaves and pretty flowers. Knowing how to grow hostas will give you a good foundation for keeping them healthy, but if you want your hostas to spread, you'll need to know when to divide them. Division lets you grow more hostas from one plant by separating the roots. You don't need to worry about dividing your hostas every year, but dividing hostas every three to five years is a good way to keep a single clump from growing too large. The best time to do this is in early spring, right as the first growth of the year emerges.

Since they haven't really started to grow yet, they're using less water. This means they're less likely to experience water stress. Dividing and transplanting is already stressful for your plants, so you don't want to stack any extra stress on top. There is also typically plenty of moisture available in spring from April showers and early-morning dew drops, so if your hostas do need some extra water, it's easy for them to access. You don't need to worry about frost damage since the weather will continue to get warmer, although you should try to wait until after the last frost date for your zone. Hostas are hardy in USDA Zones 3 through 9, so there's a broad range of frost dates and transplant times depending on where you live.

In addition to being easier for your plants, it's also easier for you to divide hostas before they leaf out. Carefully digging up and separating the roots of your plant is much simpler without having a ton of leaves in the way.

If you can't divide your hostas in spring, you may be wondering if you can divide them in other seasons. The good news is that you typically can, although they may not recover as quickly and may need extra attention. When dividing hostas later in the year, they may be more stressed by the division and transplanting. You'll likely need to water your hostas more, especially if you're dividing them during summer, when the heat is more intense. A layer of mulch can help your hostas retain more water. When dividing hostas in summer in particular, avoid moving them to a place where they'll get more sun. Since the sunlight is more intense during summer, the hostas will be at an increased risk of sunburn. This, combined with the stress of division and transplanting, can severely weaken your plants.

Fall is the second-best time to divide your hostas, so you may want to skip dividing them in summer if you're able to wait for fall. Since the temperature begins to cool and the plants start winding down for winter, there is less stress on your plant. Make sure you know how to care for hostas in fall to keep them in the best shape before and after dividing them. Additionally, don't wait too long to divide them. 

You shouldn't divide your hostas in winter, as they'll be vulnerable to the cold. If you absolutely have to divide hostas in winter for some reason, perhaps because you're moving and want to take some with you, then your best bet is to divide and pot the hostas. Bring them indoors to protect them from the cold.