The hydrangea is a spectacular, deciduous flowering shrub. A popular choice for gardeners wanting to add long lasting color and interest to their garden the large flowers that the hydrangea produces are equally as popular with pollinators. If you want to learn more about caring for these reliable shrubs, our How to Grow Hydrangea guide is full of useful information.
Why Learn How to Propagate Hydrangeas?
A common sight in garden stores and plant nurseries, the hydrangea is usually sold as a well developed plant in a 1 or 2 gallon pot. Purchasing a number of hydrangea plants can be expensive. Depending on the size and cultivar, one plant typically costs 25 to 50 dollars. A more affordable way to increase your collection is by learning how to propagate hydrangeas.
If you know how, a mature specimen can yield dozens of new plants. Not only does learning how to propagate hydrangeas saves you money it is also a good, transferable skill. Once you can propagate hydrangeas you can repeat the process on other plants.
The hydrangea is a reliable flowering shrub.
What makes the hydrangea such a good plant to learn how to propagate is that it is uniquely suited to the process. Unlike other woody shrubs, hydrangeas are reliably quick growing. If you know how to propagate hydrangeas correctly the new plants can mature and set flowers within a year.
This guide to how to propagate hydrangeas will take you through the entire process.
Warning. It is against the law to propagate hydrangeas or other plant varieties that have been patented by developers or breeders.
Plant patents typically last 20 years. Many older cultivars are unlikely to be protected. Before attempting to propagate, look at the plant nursery tag. If there is a “TM” or “®” on the label, the specimen is still under patent. This means that you are not allowed to propagate the plant without permission from the breeder.
While illegal, it is extremely unusual for patent law to be enforced against private gardeners who are simply propagating one or two new plants for their own purposes. Patent law only becomes a real problem, and is likely to be enforced, if you start to propagate hydrangeas or other plants on a larger scale.
When to Propagate Hydrangeas
The best time to propagate hydrangeas can vary depending on the type that you are growing. But, in general, most people find it best to take cuttings in the spring. Learning how to propagate hydrangeas by cuttings in early spring gives the plants plenty of time to grow and develop into viable plants before transplanting in the fall.
Additionally, it is always desirable to begin the propagation process in the spring when the plant’s metabolism and growth rate are peaking. Propagating cuttings at this point, when the plants are full of energy, makes it easier for them to develop new roots.
It is also possible to take cuttings in late summer or early fall. Like learning how to propagate hydrangeas in the spring, these can be rooted and grown on as young plants undercover before transplanting. However, late summer and fall cuttings are more prone to failure than spring cuttings.
Cuttings are best taken from soft, green stems preferably before flowering begins.
Take the cuttings during the coolest part of the day. This is usually in the early morning. You can also take them in the evening as the temperatures fall. Taking cuttings during the coolest part of the day helps to reduce the effects that heat stress can have on vulnerable stems following their removal from the parent plant.
How to Propagate Hydrangeas
Taking cuttings is the most common method to learn how to propagate hydrangeas. This is suitable for all varieties of hydrangeas including:
- Oak leaf,
- Big leaf,
- Smooth leaf.
When it comes to learning how to propagate hydrangeas, you need to be aware that each type, as well as having distinct characteristics, also has some specific needs.
The Oakleaf Hydrangea produces white flowers. Reaching a height of around 8 ft, the plants are typically hardy in USDA Zones 5 to 9.
Big Leaf types, H. Macrophylla, typically grow to a height of 6 to 10 ft. The plants flower in a range of shades from rich blues to light pinks. Hardy in USDA Zones 5 to 11, most people prefer to take Big Leaf cuttings in the fall. You can also take cuttings in the spring.
Panicle or Tree Hydrangeas, H. Paniculata, produce white or pink flowers. Hardy in USDA Zones 3 to 8 the plants reach a mature height of 8 to 15 ft depending on the growing conditions. Panicle cultivars are best rooted in the spring for transplanting in the fall.
Smooth Hydrangeas, H. Arborescens, are hardy in USDA Zones 3 to 9. Reaching a height of 3 to 5 ft, white flowering smooth cultivars are typically smaller than other varieties of hydrangea. They can be propagated by both root and stem cuttings.
Despite the differences in cultivars, propagation is largely the same.
Before learning how to propagate hydrangeas take a little time to research the variety that you wish to cultivate. This helps to make both growing and propagation a lot easier.
How to Take Cuttings
Now that you know the best time to take cuttings, it is time to learn how to propagate hydrangeas.
Before starting the process, make sure that you have everything that you will need to hand.
You Will Need:
- Sharp pruners,
- Rubbing alcohol,
- Cotton ball,
- Powdered rooting hormone,
- 8 to 10 inch terracotta pot,
- Sterile seed starting soil.
Before learning how to propagate hydrangeas take the time to sanitize your pruners or garden scissors. This can be done by dabbing Rubbing Alcohol onto a cotton ball. Wipe the blades and the handle. Sterilizing your tools helps to prevent fungal disease or infestation transferring from the parent plant, or other specimens in your collection, to the new cuttings.
Take cuttings from mature hydrangea plants. Cut 2 inches below the leaf node on a green, healthy branch that has not yet formed any flower buds. Avoid taking cuttings from older, woody stems. Softwood cuttings taken from tender green stems root more easily than those taken from woody, older stems.
Your cutting should be 6 to 8 inches long. I like to take a few more cuttings than I need. This helps to safeguard against one or two of the cuttings failing.
Take cuttings from healthy branches.
Next, trim all but the top 2 to 4 leaves from cutting with your pruners. Be careful not to damage the stem as you do this. When cutting away the leaves, allow some room between the main stem and cut. Not cutting too closely to the stem helps to keep the integrity of the stem intact.
If you are learning how to propagate Big Leaf hydrangeas you can also remove half of each of the remaining upper leaves with scissors or pruners. This reduces the pressure on the stem to absorb enough moisture to keep the leaves green and healthy. If you are learning how to propagate smaller leaf cultivars, there is no need to cut the leaves in half.
Dip the stem in Bonide Rooting Hormone. Whilst not strictly necessary, using a rooting hormone encourages root production. This boosts germination rates.
Potting the Cuttings
Once you have prepared the cutting, the next stage in learning how to propagate hydrangeas is potting and rooting the cutting.
An 8 to 10 inch pot holds several cuttings. Make sure that it is clean and has drainage holes before filling with a seed starter potting mix.
Coarse sand, vermiculite or a soilless mix of peat moss and horticultural perlite can also be used to root the cutting. Do not use soil from the garden or a soil mix that is rich in manure or fertilizer content. A soil mix that is too rich in nutrients can burn the cuttings and new roots.
Moisten the soil.
Plant the cuttings by embedding them to the depth of the remaining leaves. At least 2 leaf nodes should be covered by the potting medium.
Pack the seed starter mix around the stem to hold the cutting in place. Remoisten the soil with a Plant Mister Water Spray Bottle.
After plating, the cuttings need to be placed in a safe position where they can enjoy constant, steady temperatures. A Propagator with Humidity Vents is ideal.
If you do not have access to a propagator you can place the cuttings in a clear, plastic bag. Use HAINANSTRY Bamboo Stakes to hold the plastic up so that it doesn’t contact the cuttings.
Place the cuttings in a location that enjoys lots of bright, indirect light. Do not be tempted to place them in a direct light position. This can bake and rot the cuttings.
Regularly check the condition of the cuttings, moistening the potting mix when it feels dry to the touch. An important part of learning how to propagate hydrangeas is keeping the soil consistently moist but never soggy.
Caring for Cuttings
Roots can form as soon as 10 days after planting. However you should not disturb the cuttings just yet. Allow 4 to 6 weeks to pass before transplanting. This gives the cuttings time to develop a healthy root system. Once roots have started to develop, fresh green growth quickly follows. Continue to keep the soil moist. Larger cuttings can be watered with a gentle spray from a watering can.
After a few weeks of producing new growth, or possibly sooner in some cases, you need to transplant the individual cuttings into their own pots. These can be filled with fresh, general purpose potting mix.
To repot, make a hole in the center of the fresh potting soil. Carefully remove the now rooted cutting from the original pot. When handling, try not to disturb the roots too much. Using sharp scissors to cut away the edges of the pot can help you to remove the cuttings without causing too much disturbance.
Plant the cuttings to the same depth as in their previous pot. Gently firm the soil down and moisten.
Larger cuttings can be transplanted directly into the garden.
Once you are able to transplant the cuttings into individual pots, you can treat them as mature plants. This means watering once a week.
Continue to grow the cuttings on undercover until you are ready to transplant.
How to Transplant into the Garden
Harden off the cuttings before transplanting. This helps to reduce the potentially harmful effects of transplant shock. As the plants acclimatize, take the time to dig over the soil, working in any necessary amendments as you do so.
Remember that the flowers of some cultivars, such as the big leaf hydrangea can change color depending on the pH level of the soil. If the soil is overly acidic the flowers are blue, turning pink as the soil becomes alkaline. A soil test kit accurately measures the pH level of your soil. If used before planting, you can make any necessary amendments to the soil.
Make a hole in the soil. This should be large enough to comfortably hold the plant. Remove your young specimen from its pot and place in the center of the hole. Again take care not to damage the root system.
When you are happy with the position of the plant, firm down the soil and water well.
Regularly water the plants after transplanting, once the plants are established and new growth is visible you can steadily reduce the amount of water that you are applying.
If you are transplanting in the fall, the plants should flower the following spring or summer.
Learning how to propagate hydrangeas is not as daunting as it may seem. An affordable and relatively simple way to increase your plant collection, the skills learnt here can be transferred to the propagation of other plants such as the Penta flower or Bay Laurel plant.