New to Japanese Larches/ seedling thread?

[SpencerI]

I’m very new to Japanese Larches. And I was hoping to get some guidance. I did a search for larch threads and couldn’t see a seedling thread.

In spring of 2024, I planted a ton of J. Larch seeds. Many didn’t survive this past winter due to the pots freezing. I have had a huge explosion of growth from the 15 or so pots I have left. Right now, each pot has about 3-7 seedlings per pot. My plan is to separate the seedlings next year in late winter/ early spring. What else should I do when I separate them? Below is a picture of one of the pots. The tallest larch is 10-11in (25-28cm) tall. Many are about 7in (17cm).

What is the best way to separate them?

When I repot, should I root prune or wait another year?

What soil have you seen success with for larches?

What else has worked to increase size and strength?

How often should I fertilize? I’m currently applying liquid and granule fert about every 2-3 weeks.

 

[rockm]

Unfortunately larches don’t do very well in this area. It stays too hot in the summer here. They grow fine just north of here in higher elevations in Pennsylvania and the northern edge of Maryland. Were are near the southern edge of the North American larch range. They don’t grow in the Va mountains but have sporadic presence. The higher mountains of West Va. there’s a reason for that explained below

I’ve tried Japanese larch and North American larch over the years here in NoVa Typically they’re initially fine the first couple of years. Then they begin to decline slow growth in Spring, yellow/brown foliage in summer. Same the following year or two then one spring they’re just too weak to bud

It is the hot summers here that cause the decline. Not necessarily hot day time temperatures but nighttime temps that don’t drop below 70 for a month etc. that nighttime cooling is a feature of their native habitats.

Not to be a downer but just to temper expectations

You may have success no reason not to try.

 

[Wulfskaar]

Unfortunately larches don’t do very well in this area.

Looks like he's in Washington state.

 

[rockm]

Looks like he's in Washington state.

Oops. Arlington. I need glasses disregard my post

 

[WNC Bonsai]

I grow both American and Japanese larch in western North Carolina (Asheville). The Japanese larches are very strong growers and I get several flushes per year whereas with American larch typically only two flushes. There is an American in the bonsai collection at the arboretum here that has been grown here since 1976 so contrary to what @rockm says they can be grown far south of their range however they are very sensitive to deal with here.

Now as to your J. larches. If you go at it at the right time just as the buds are swelling and about to break or even show green then you should be able to separate the roots of those in the same pot. Just swish them in a bucket of water to remove the soil and repot individually. I fertilize mine with liquid fertilizer every 2 weeks and they grow like crazy. I grow them in a mix of pumice, permatil (heat expanded slate), and composted pine bark with about 50% bark to keep them hydrated. It is important to keep them cool in summer. I usually move mine to part shade in July to prevent heat stress. I figured this out several years ago when I left some in the sun in August and lost 2 in a single day. Also be very careful with root pruning as they are very root sensitive. Get over aggressive and they die on you, maybe not immediately but later in the summer heat.

You can get thumb thick trunks in 2-3 years if you like straight trunks for a forest. For taper, cut and regrow repeatedly and wire to shape the trunks and branches. You will need to keep a close eye on any wire as they can thicken quickly.

 

[SpencerI]

Oops. Arlington. I need glasses disregard my post

LOL!!!! It’s all good! No worries.

 

[SpencerI]

I grow both American and Japanese larch in western North Carolina (Asheville). The Japanese larches are very strong growers and I get several flushes per year whereas with American larch typically only two flushes. There is an American in the bonsai collection at the arboretum here that has been grown here since 1976 so contrary to what @rockm says they can be grown far south of their range however they are very sensitive to deal with here.

Now as to your J. larches. If you go at it at the right time just as the buds are swelling and about to break or even show green then you should be able to separate the roots of those in the same pot. Just swish them in a bucket of water to remove the soil and repot individually. I fertilize mine with liquid fertilizer every 2 weeks and they grow like crazy. I grow them in a mix of pumice, permatil (heat expanded slate), and composted pine bark with about 50% bark to keep them hydrated. It is important to keep them cool in summer. I usually move mine to part shade in July to prevent heat stress. I figured this out several years ago when I left some in the sun in August and lost 2 in a single day. Also be very careful with root pruning as they are very root sensitive. Get over aggressive and they die on you, maybe not immediately but later in the summer heat.

You can get thumb thick trunks in 2-3 years if you like straight trunks for a forest. For taper, cut and regrow repeatedly and wire to shape the trunks and branches. You will need to keep a close eye on any wire as they can thicken quickly.

This is great information! So far, I have left larch seedlings in full sun. The temps haven’t really hit the 80F (27C) for more than a day or two at a time. I make sure to they don’t get too dry and water them when soil is just moist.

But it seems like I am on the right track. I’ll wait for spring and the buds to erupt with foliage and repot. And the soil combination sounds great. After the repot, i’ll move them into that soil.

Thank you!

 

[Shibui]

Do as much root prune as you feel comfortable with at the first repot. It's important to begin working toward good nebari and the earlier you start the better. Younger trees recover from root pruning much, much better than older trees so first few repots is the best time to cut roots hard.

I separate seedlings by gently jiggling the trunks. A straight pull seems to lock the roots together but repeated pull and release seems to let the roots slide past each other more easily.

Increasing trunk thickness is the same for most species - time and growth. The more you allow the tops to grow the thicker the trunk - just be aware you will need to also manage to keep some viable buds and shoots down low that you can chop back to.

You might like to try wiring some of the trunks to get some initial trunk bends while they are still really flexible. Others can be developed by cut and grow which should also add bends and taper to the trunks.

Liquid and granule fert every 2-3 weeks should give good growth.

Of all the Larch species, Japanese Larch seems to be the hardiest. It's the only one we can keep alive down here where Summers are hot and dry.

 

[Deep Sea Diver]

I’m very new to Japanese Larches. And I was hoping to get some guidance. I did a search for larch threads and couldn’t see a seedling thread.

What soil have you seen success with for larches?

Larches out here like a free draining media that is moisture retentive. So if pumice, add about 20 composted manure. Be sure to moss the surface out here. Avoid full sun, especially during our summer heat waves..

What else has worked to increase size and strength?

To add girth and a just bit of taper, treat well and occasionally prune the tops (wire a new apex as needed) to force the growth downwards.

How often should I fertilize? I’m currently applying liquid and granule fert about every 2-3 weeks.

Not clear on what present practice is. Are the trees getting both granules and liquid ferts every 2-3 weeks? If so, switch to time release pellets like Osmocote Plus. Use these every 2-3 months. Then liquid fertilizer, Miracid etc every 2-3 weeks.

Heel into ground during winter. Protect from varmints like squirrels and rabbits.

Cheers
DSD sends

 

[SpencerI]

Do as much root prune as you feel comfortable with at the first repot. It's important to begin working toward good nebari and the earlier you start the better. Younger trees recover from root pruning much, much better than older trees so first few repots is the best time to cut roots hard.

This is great! I’ll do a root pruning in the spring. Are Larch’s like Japanese Black Pines where they can be root pruned near the end of Fall?

Increasing trunk thickness is the same for most species - time and growth. The more you allow the tops to grow the thicker the trunk - just be aware you will need to also manage to keep some viable buds and shoots down low that you can chop back to.

How is back budding on Larch’s? Is fairly easy like a JBP?

 

[SpencerI]

Larches out here like a free draining media that is moisture retentive. So if pumice, add about 20 composted manure. Be sure to moss the surface out here. Avoid full sun, especially during our summer heat waves..

To add girth and a just bit of taper, treat well and occasionally prune the tops (wire a new apex as needed) to force the growth downwards.

Not clear on what present practice is. Are the trees getting both granules and liquid ferts every 2-3 weeks? If so, switch to time release pellets like Osmocote Plus. Use these every 2-3 months. Then liquid fertilizer, Miracid etc every 2-3 weeks.

Heel into ground during winter. Protect from varmints like squirrels and rabbits.

Cheers
DSD sends

The next time we get hotter temps, I’ll move them so they get afternoon sun protection.

For the fertilizer, I’ve been alternating with high nitrogen granule fert that slowly dissolves over time. The stuff I am using is Scott’s starter grass fert because it’s a high ratio of 24-25-4. I only use a tiny pinch. The other times I use liquid miracle-gro.

I have used Osmocote plus in the past. I’ve mixed it into the soil and sprinkled on top of the soil but it doesn’t appear to dissolve or release. I have pellets on some other trees that has not dissolved from last year.

 

[Deep Sea Diver]

Those leftover pellets are empty .

Osmocote is water activated and slowly dissolves via the membrane (called a prill). A person will not be able to see this slow release occurring. However after 2 months. depending upon the type used, the effective fertilizer dose will be expended.

We normally put the perilla on the surface upon application. Once done, they often blow away or float out during watering.

Recall the actual NPK etc dosage will depend upon the amount used, thus a 1/2 dose for the prescribed area cuts the effective NPK etc in 1/2 over the prescribed time.

Cheers
DSD sends

 

[SpencerI]

Those leftover pellets are empty .

Osmocote is water activated and slowly dissolves via the membrane (called a prill). A person will not be able to see this slow release occurring. However after 2 months. depending upon the type used, the effective fertilizer dose will be expended.

We normally put the perilla on the surface upon application. Once done, they often blow away or float out during watering.

Recall the actual NPK etc dosage will depend upon the amount used, thus a 1/2 dose for the prescribed area cuts the effective NPK etc in 1/2 over the prescribed time.

Cheers
DSD sends

I will keep on eye on that! That’s good to know. And I’ll make sure to also use the full dose when I can.

 

[WNC Bonsai]

This is great! I’ll do a root pruning in the spring. Are Larch’s like Japanese Black Pines where they can be root pruned near the end of Fall?



How is back budding on Larch’s? Is fairly easy like a JBP?

No, they are VERY sensitive to when and how you root prune so plan to lose some learning. As I said above repot and do minimal root pruning in the spring just as the buds swell and look a nice gold color or even when you can see a little green. They do not back bud worth a hoot on old wood, only on new wood. Occasionally you may get a bud to pop on old wood but don’t depend in it. Consequently you need to constantly keep chasing back growth on branches or else you will be left with long leggy branches and no back buds to replace them with.

 

[SpencerI]

No, they are VERY sensitive to when and how you root prune so plan to lose some learning. As I said above repot and do minimal root pruning in the spring just as the buds swell and look a nice gold color or even when you can see a little green. They do not back bud worth a hoot on old wood, only on new wood. Occasionally you may get a bud to pop on old wood but don’t depend in it. Consequently you need to constantly keep chasing back growth on branches or else you will be left with long leggy branches and no back buds to replace them with.

This is perfect to know. With how the trees look now, it would be good to start pinching off some of the top shoots to help back bud on the new wood or shock the tree?