What are we doing wrong with Hydrangeas?

We have a couple of Hydrangeas in pots in our back garden. They have come back for the last three years with no problem but look very sparse. I changed the top third of compost as I do every year.They both seem healthy and are producing nice green leaves but the stalks are very sparse. I wonder what are we doing wrong? When they die back should we be cutting the dead stalks back? We have a huge Hydrangea planted in the front garden which grows back full and beautiful every summer. Maybe its the feeding that we are doing wrong. Can anyone help please?

 

It is hard to compare hydrangeas in different environments and locations and expect them to behave similarly. You also cannot "see" what kinds of root systems they all have.

"When they die back should we be cutting the dead stalks back?" Yes but do not be in a hurry. You will need to do a scratch on each stem to confirm that they are dead. Do the test very, very carefully in order to see if the stem has "green" or not. Late frosts can zap the leaves and leave the stems alive. If that happens, you have to wait from 2-4 weeks to see if the stem leafs out or not. Useful hint: if the stem does not leaf out 4 weeks after your average date of last frost then I would prune the stem all the way down. If the stem partially leafs out (the lower half) then I prune the stem partially until my cut shows some green in the stem; or prune above the topmost set of leaves

"I changed the top third of compost" Do this carefully because most hydrangea roots are shallow, tiny and fibrous, found at a depth of just 10 cm deep or less. Make sure that the roots are not too deep due to frequent compost applications. Note: if you "disturb" the roots too much when changing the compost, root injuries may cause problems to some of the stems/leaves. Of course, I add organic compost or composted manure only to the hydrangeas that are planted in the garden every few years and I do not "change the compost" every year. I am not sure how the roots would respond if they end up planted too deeply.

Inconsistent watering -periods when the soil gets watered, then becomes dry at a depth of 10 cm or less for many days, then gets watered again, then becomes dry again for many days- can also result of live stems with small foliage. Avoid inconsistent watering (as best as you can) by checking the soil often: insert a finger into the soil to a depth of 7-10 cm (in pots) and water if it feels dry or almost dry. The other one that is planted in the ground can be checked at a depth of 10 cm. Aim for evenly moist soil as best as you can.

If the pots are left outside during times of freezes or frost, consider: bringing them temporarily inside; watering deeply (the night before a frost for example) if left outside and the potting soil is dry; and covering them with frost cloth or blankets (but make sure the blankets do not weigh enough to bend or break the stems). I recently (February) had to winter protect them due to a big freeze by bringing them inside for a few days but several plants were left outside and I put blankets and some incandescent light bulbs from Christmas decorations around them. The aim was to protect the "invisible" flower buds at the ends of the stems in mopheads that bloom only once in Spring.

 

Thanks you so much for that my friend. What I don't understand is the one in the front garden gets nothing done to it and thrives every year, so why the drama with our potted ones out the back?

 

Elloooo Leth

I find with Hydrangeas in pots they do need more attention..The clue is in the name 'Hydro' if you get me...they thrive on plenty of watering and in pots they do dry if you're not careful

 

For reasons behind the drama, remember to consider that which you cannot see. Typically, a hydrangea planted in the ground can develop a large/wide root system while a potted hydrangea will have a root system that is limited by the size of pot. Plants in pots also require frequent watering while plants in the ground can access water from much farther away than potted plants. In the pots, the roots can only grow so much but if the hydrangea is in the ground, its roots can grow farther away and deeper to get nutrients and water. The soil in the top of the pots also tends to dry out faster. Pots also heat up and cool down faster than a mulched plant in the ground. When plants are in pots, these temperature changes can slow the plant growth.

 

Thanks for all the help guys. We will take it on board and hope to have better looking plants next year.