Do not fertilize now.  Yes, this is dormant season for it.  Put it by a bright window, if you can.  Put it outside in May.

You may want to have it flower in spring so insects can pollinate it and then you'll get lemons in about January. You can encourage flowering by pruning and drought stress (letting the soil get dryer than usual) before you put it outside. Resume normal watering outside. 

Fertilize in April-May when it gets new growth. Use a citrus fertilizer if you can find it. 

Ellen

Thank you for your response. Part of my concern is that it has dropped two more leaves; part is that is does seem to be showing new growth. I'm attaching pictures of three new buddings, if that's the word. Could it be that sitting in front of a window plus receiving 10,000 lux of full-spectrum light is too much? Should I back the light away, or skip it altogether? I do realize that losing a few leaves could just be a matter of the mixture of sphagnum and perlite holding too much moisture.

Leaf drop on indoor plants is a normal reaction to the stressful conditions they experience inside - lower light intensity, lower humidity, and short daylength. It is a somewhat accelerated progression of their normal growth pattern, which is to shed the oldest leaves when they have outlived their usefulness. Because growing conditions aren't favorable, the plant conserves its resources by jettisoning a few leaves that are too costly for it to keep alive. Normally, during the growing season, there's enough new growth replacing what's lost that the plant doesn't look too bare, but in winter, since new growth is minimal or non-existent, plants can become sparser.

Using a grow light to supplement its light exposure is helpful, and you can also use it to give it a longer "day" than our natural daylength by keeping it on a bit longer after the sun sets (or starting it before sunrise, if you prefer). Many indoor growers of tropical plants using plant lights have their lights on for about 12 or so hours each day. Putting the light on an outlet timer helps keep the timing consistent and easy to manage. Between about May and October, as Ellen mentions, it will greatly benefit from being grown in partial shade to mostly sun (as it adjusts gradually) outdoors. Although the oldest leaves that recently fell may not have been accustomed at first to the brighter light coming from the combination of the grow light plus the window natural light, it's not too bright for a sun-loving plant like citrus and the new growth will appreciate the supplementation.

A humidity level of 40% is not bad for indoor air, which is often dry enough to cause plants stress and promote pest problems. If you wish, you can boost it a bit further by using a room humidifier.

The appearance of new growth is a good sign, and may be in response to the grow light being used. Citrus grow best when allowed to get fairly dry in-between thorough waterings. New branch growth coincides with new root growth, so to keep the roots healthy, avoid over-watering. Pot shards used in containers aren't helpful in improving drainage (they can hinder it, actually) and take up space roots would need to grow in, but in this case, given the apparent small size of the plant, it may be months or more before the roots will need that space. As it gets larger, though, repotting with fresh soil and without pot shards is recommended, in any container that isn't much larger than the root mass at that time and has at least one drainage hole in the bottom of the pot.

More tips and recommendations for growing citrus indoors in our area can be found in this article: https://extension.umd.edu/hgic/topics/growing-dwarf-citrus

Miri

Your answer is extremely helpful, Miri, along with the link. Many thanks.

We've already pinched off one new branchlet that started fairly low on the stem.

What I'm wondering about now is two things. One, whether the topmost growth should be pinched off now, or all new growth, given that it's supposed to be the dormant season. Two, whether having the 10 000 lux light over it encouraged the straight-up growth and it would be better to shine the supplemental light from the side.

David

David,

The new growth looks good, and its appearance during the "dormant" season is not harmful. (Quotes used because it's typically a season when no above-ground growth occurs due to the lower light, etc., but it's not required for this species.)

We suggest allowing it to keep growing anywhere it's putting out new growth (no harm in removing what you already did, but don't remove any more). If the grow light is above the plant, that's fine as it will promote more even, symmetrical growth. If placed opposite the source of natural light, it probably won't cause more growth in its direction, but it's possible; in that case, overhead would be better than asymmetric lighting, though you could also just give the plant a quarter-turn once a week to help it stay balanced. Simplest, though, would be to keep it roughly over the top of the plant.

In general, plants grow most actively from the stem tips, and this growth suppresses the growth of buds beneath it via hormones. This is called "apical (as in apex) dominance" and can be manipulated by pinching off the tipmost growth points to decrease the flood of hormones and allow the lower ones to emerge. Since lower buds usually emerge in groups (as opposed to single buds), this encourages bushiness over time. For the future, this may be useful to control the plant's height as well as develop a nice full shape. For now, the plant is young enough and in low enough light (relatively speaking, compared to in-season summer light) that pinching it may set it back more than desired. In addition, active stem growth stimulates active root growth, so it's probably best to allow it to establish more roots at this point, especially if it is to be repotted sometime this year.

Miri

While both Meyer lemons are doing fine, as far as I can tell, it's time to get guidance on a couple of additional issues having to do with bringing them outdoors.

Here's their status: Meyer is now ~14 in tall, with the stem about 3/8 in max D. Pinchy, the pinched-off and then nonetheless comfortably rooted youngster, is about 1.5 in tall. (I can't find my outside caliper, so I won't guess stem D.) I started putting them out on a generally sunny deck by day, during the hours when the temp was in the mid-50s or higher, bringing them in after dark, when it got below 51 at the coldest part of the night. I've left them out continuously the last 48 or 72 hours. They seem okay with this.

Question 1: Rainy days and nights. Both are in pots with drain holes. Should I nonetheless bring them indoors when we have ongoing rain, or are we close enough to growing and even fertilizing season that I needn't fuss about this?

Question 2: Cicadas. Are they vulnerable? Do I need to keep Meyer and Pinchy in(door) purdah once the buggers start their mating dance?

Thanks,

David

On 1/4/2021 10:42 AM, Ask Extension wrote:

Rainy days are not a concern; if anything, the plants may appreciate the purer water source to compensate for any mineral build-up that may have occurred in the potting soil from tap water over the winter. Containers that drain well won't be easily waterlogged from too much rain. Usually, plants from indoors are put into shade first for a couple of weeks until they can acclimate, rather than directly into sun, but the seem undamaged so you're probably ok continuing to do so. Citrus are pretty tolerant of cool temperatures, so you may be able to leave them out in evenings cooler than the low 50s, but either way avoiding frost is advisable.

The new growth looks like it might be developing a bit of chlorosis, so if it's been awhile since you've last fertilized, you can resume doing so now at a dosage recommended on the label. If in doubt about dose when a range is given, start at the lower end and see how the plant responds over time. (It may take at least a couple of weeks to really make any impact.)

It's not likely the cicadas will take any interest in the larger citrus, and the smaller one is way too small (currently, at least) to be at risk. You can always secure netting over the larger plant during cicada breeding season, just in case, if you want. Keeping the plant outdoors (and netted) would be preferable to bringing it back inside. See guidelines here: https://extension.umd.edu/resource/cicadas

Note that the citrus web page link we gave you earlier is now out-of-date; our Extension website has been renovated, and here is its new address if you need it: https://extension.umd.edu/resource/growing-dwarf-citrus

Miri

Thanks!

We were considering buying and planting partridge berry. Then we found something in our yard that looks as though it might be partidgeberry. Is it? If it's not clear, what else might it be? Anything toxic, or terribly invasive? If it is an innocuous groundcover, partridgeberry or a similar plant, possibly (I've got no shame) a partridgeberry family member, how can we encourage its spread? Will it choke out dandelions? Or lily of the valley, which though toxic and somewhat invasive, I enjoy? If we spread it to the appropriate locations, would it--could it--does anything choke out English ivy, or (wishing) poison ivy?

Thanks,

David

Hello David,

This is indeed Partridgeberry (Mitchella repens), and healthy-looking patch at that. However, in our experience and observations, this species does not out-compete other vigorous groundcovers, especially invasive ones like English Ivy. In the wild, it is uncommon to see a sizeable expanse of this with little else growing among it; usually, they weave in-between other plants on the woodland floor or in the crevices between boulders where soil collects. To help it along and maintain its vigor, we suggest removing any non-native ground-covering competition from the areas where you want it to spread. They are fairly slow-growing, so filling-in an area will take time, even if growing by itself.

Miri

Thanks, Miri!

You're welcome!

More Photos of Meyer, our lemon.

We want to check on the health of our our Meyer Lemon. We brought it and our herbs in before the temperatures got down into the 40s at night. The thyme isn't doing well, but that may be a matter of watering; no worries.

The moisture meter has been telling me the soil in the middle of the pot was pretty moist, and somewhat unevenly so. Now it's down to mid-range, though quite dry near the surface. I have it in front of a picture window with regular glass, not low-E, and augment that with high-color-temperature table lamps to each side, staying on a couple of hours past dark. (I have no idea how many lumens it gets.) At night, I have a humidifier keeping the air ~40% rel humidity. I added citrus fertilizer maybe a month ago, and don't plan to do so again till Spring, unless you advise otherwise.

It's lost quite a few leaves and, eventually its buds. It has more leaves curling or yellowing. I don't know whether this is normal hunkering down for the winter, or whether it's hurting and there's something I should do. It does have new growth. I'll try attaching photos to this message and sending a second message with more photos.

Thanks,

David

Hello David,

Thank you for the photos. We can't see too clearly what may be causing the look of debris on the leaf undersides, though aphids are likely. Scale insects can infest citrus too (usually brown soft scale), but they tend to be more obscure and well-hidden. If you can, give the leaves a good shower or wipe-down with water and inspect the leaf undersides after a few days to see if anything returns. (If it does and you see pests, either keep rinsing/wiping it off or treat with horticultural oil or insecticidal soap.) Mites can be problematic on citrus in dry conditions, but we don't see their feeding damage on the foliage, so this is less likely.

If this pot has an attached saucer (looks that way from the photo, but hard to tell), remove it so it drains freely. (You can set it back on top of this or another saucer, so long as the pot base doesn't sit in collected moisture.

Moisture meters may or may not measure soil moisture accurately - we have not tested them. Instead, you can double-check the plant's soil moisture by touch; it's simplest and the most straightforward to just stick a finger into the soil about two or so inches down to feel the moisture level. Alternately, you could use a wooden rod or sharpened wooden pencil to see how damp the soil makes the wood when you probe it to a depth of perhaps three inches. Citrus is more forgiving of getting slightly too dry between waterings than too wet. Deeper soil in the pot tends to stay wetter for longer than shallower layers of soil. Retention of moisture in the potting mix depends on many factors, including the composition of the mix itself plus ambient humidity, plant growth rate, ambient temperature, and so forth.

You are correct in assuming that additional fertilizer will not be needed until spring.

Thyme can struggle indoors. They benefit from bright light, relatively cool temperatures (the same as the citrus), and must have good soil drainage and not stay too wet. This plant appears to be in a pot a bit too large for its needs (which risks staying wet for longer after each watering), but at this point, just keep an eye on it and try to let it dry out at least an inch down between waterings. We don't see a saucer under this pot, so if there are no drainage holes in that container base, that may deprive the roots of oxygen over time if the soil can't drain excess moisture after watering. In that instance, repotting may be prudent now.

Leaf drop and bud blast (the shedding of unopened or prematurely spent flowers; young fruits can abort too) are common stress responses when plant growing conditions are changed, such as by moving them in for winter. Leaf yellowing and drop can also occur due to over- or under-watering, so monitoring will help you avoid either; shedding due to the adjustment period should end soon, but some plants adjust much more gradually than others. Leaf curling could be due to a range of issues, from the aforementioned adjustment to pest damage to low humidity. Your target of about 40% ambient humidity should be fine.

New growth on the citrus is a good sign, though don't be alarmed if it slows and stagnates for the winter. Overwintered tropicals tend to just stall and survive winter as-is before resuming growth in spring. They may not replace foliage that is shed during this time, but that's ok so long as the overall health of the plant doesn't decline or pest outbreaks don't weaken it too much.

Miri

Thank you, Miri.

You were right that there was water in the saucer under Meyer. OTOH, I 
had to stick a finger into the soil a bit more than 2 inches to begin to 
feel moisture. Go figure. FWIW, I have to stick our moisture meter about 
3.5 inches down to get out of its "dry" zone; 2 inches barely budges it 
away from the bottom of the dry end of the scale.

I don't see anything crawling on Meyer, but it sure looks as though a 
few leaves have been chawed. Some of the leaves have copious brown 
flecks on the undersides, as though dirt had gotten splashed there in a 
rainstorm. A curled leaf, though, is spotless. I've added close-ups, in 
case they modify your recommendations.

Thanks agian, and for that matter again,

David the lousy typist.

I've again attached pics plus more in a separate message.

Try foregoing the meter for awhile and just use the finger or wooden stick test method. If the soil doesn't feel moist two or three inches down, you might be able to water now. Water in the saucer may have over-soaked the lowest soil depths, but there's nothing you can do about that except to just remove the saucer (or raise the pot above it so it clears any drainage pooling) and give it time to dry out after the next watering. Watering and humidity irregularities can lead to leaf puckering and distortion as a young leaf is expanding fully. While not serious in terms of plant health, deformed leaves do not correct their shape after the environmental conditions are settled. That's not a point of concern, though, if the occurrence is scattered and not severe.

We can't see what the debris on the leaf backs may be. We don't see scale; there are no clear signs of aphids; mites would be too small to see well at this distance, but would be visible (though slow-moving) under a magnifying glass. None of those pests are capable of chewing leaves; they only suck plant sap/juices through a straw-like mouthpart. We don't see any chewing damage, and the only culprit for chewed leaves indoors might be slugs/snails, but their glossy slime trails would give them away.

Rinse off the debris - soil splash is a very likely possibility - and see if it returns in a week or so. If blister-like scars are seen on the lower leaf surface, that could be edema - cell damage due to excess water in the leaf. While not reversible, it's not serious when minor and can be prevented in the future by watering only when necessary.

Miri

You're a gem

You're welcome.