Please help - potted Agastache dying back

Hi!
I'm new to this forum and looking for help with my potted Agastache.
I bought it last September and kept it in the same plastic pot over winter. This spring I planted it into a pot (I think it's about 10 liter max). When planting I added a little GrowChar fetiliser and it went up to 1 meter high with healthy foliage colour. Then about 6 weeks later the older leaves started to yellow and over time the entire plant lost it's deep green colour. The older leaves are now drying slightly and the yellowing slowly continues to go up towards the top. I didn't have GrowChar left at that time and added another organic fertiliser (called Charge from Ecothrive, consists of mealworm castings (NPK 3:2:3). It was just over 2 weeks ago. However, this made no impact. I will be using GrowChar again but I'm worried that the cause is something else than a deficiency. Although according to Google pics it looks like Nitrogen deficiency.
I considered that it might need more root space and thought to plant it out, but really want to keep the plant potted as I live in a rented property and want to keep my lovely Agastache when move. If you see the size of some plants growing in the tiny pots in the nurseries, one would assume that it's possible to grow the Agastache in the pot I have. Does anyone have any advice?
Is it possible that the last fertiliser was not good enough and I should just apply a new lot? Or is it another issue and I should avoid overfertilizing it? Btw, when portioning the fertiliser I'm always on the cautious side and apply just below the recommended volume.
Thank you!

 

Hello Organic Gardener

I grow lots of agastaches and despite their reputation for liking poor dry soil etc., they do need watering every so often esp in containers. However, they do much better in the ground too...their roots demand the space.

They will grow in containers though.....I always have a few excess plants growing in pots and they do well......simply making sure they don’t dry out

A tomato, high potash, fertiliser once a week or fortnight would be better than what you are currently using I think. Yes, you prob are over feeding it too....this produces lush foliage at the expense of flowers.

Despite your reluctance, I would plant your agastache in the ground. Water it well and only water again sparingly.

Take cuttings this month.....grab some perlite and mix 50/50 mpc ....and you will have plants for next year

I grow Black Adder, Sangria, Blue Boa, Summer Sky and several more. What variety do you have ?

Oh! Welcome to the forum

This is Black Adder in the distance and Summer Sky in the foreground. These were all from cuttings taken last August

 

@Verdun How do you take Agastache cuttings? I had 'Black Adder' growing in my garden and really miss it now! 'Summer Sky' looks beautiful next to that pinkish/white-flowered plant you have, you do have a great eye for good colour combinations, Verdun! An Astrantia?

Nick

 

Hiya Nikalaos and thanks

You can take cuttings now and through to the beginning of September.......I prefer to take them in July or early August when they will make sizeable plants to better overwinter.
Take soft wood, top 3” or so, cuttings without any bud or flower or side shoots of similar length. Strip most of the leaves, half perlite and half mpc, and insert around the edge of a 9cm pot. Water and cover with polythene bag or cold propagator and leave in sheltered warm spot outside. You can pot on individually into 9cm pots or prick out into trays, according to their size. You will need to overwinter in a frost free environment...gh, window sill, etc. In spring pot on again to make garden size plants for the summer.

Some agastaches are easier than others.....Blue Boa for example but some need some hormone rooting gel/powder

If you buy an agastache now why not take cuttings from it? Enjoy the main plant now and prepare for next season too?

Yes an astrantia....it’s Sunningdale Silver a variegated sort. I grow it mainly for its beautiful spring and early summer foliage. I grow a few astrantias here

 

@Verdun Interesting, I didn't even know there was such a thing as a variegated Astrantia, shows you how much I know. Definitely having that one, it's lovely and should do well in my heavy clay soil! Yes, I think I'll be completely unadventurous, get 'Black Adder' again and take some cuttings, haha! Looks like my little propagator will be full of cuttings this year, as my Erisymum 'Bowles Mauve' is getting old and leggy and I want some more Verbena bonariensis 'Lollipop'. Verbena bonariensis was the first plant I grew from seed as an adult, given away with a newspaper. It's what started my fascination with gardening! Thanks for the cuttings advice!

Nick

 

Getting the bug Nikalaos
Yep, all astrantias will enjoy heavy clay soil. Jumble Hole is a great white one, Roma a good pink, etc.,but there are lots of varieties out there now
Bowles Mauve? Great for a couple of years or so then flowering dwindles. It’s another plant to take cuttings from every year